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Jun 19, 2018
Titan could be a youthful object.
The wine of youth does not always clear with advancing years; sometimes it grows turbid.
— Carl Jung
Planetary scientists maintain that Titan’s nitrogen and methane atmosphere must be constantly replenished, because ultraviolet light from the distant Sun dissociates gas molecules. Theories about how the Solar System formed suggest that its atmosphere should have disappeared long ago. That idea led astrophysicists to imagine the evaporation of “liquid methane lakes” sustaining its dense clouds.
However, when the Huygens lander touched down on a flat, rock-strewn plain no methane rain was detected, and no hydrocarbon pools existed anywhere nearby. Instead, Titan exhibited a dry surface. Images revealed a rocky landscape with a sandy consistency, and a field of small, water-ice pebbles at a temperature of -179 Celsius. Huygens did not detect any liquids.
Cassini’s observations of so-called “riverbeds” were, in reality, dark, flat channels, with no evidence of flowing liquids. Similar rilles are present on the Moon. Electric Universe theory proposes that such “sinuous rilles” are scars left by plasma discharges of immense proportions. Every body in the Solar System, other than the gas giant planets and some moons, are home to rille structures. Without exception, there are steep-walled, meandering, flat-floored canyon formations everywhere.
Wal Thornhill observed that Cassini’s images of Titan are:
“…typical of arc machining of the surface. I would compare them directly to the scalloped scarring on Jupiter’s moon Io and the flat, melted floor depressions that result. Such floors would be expected to give a dark radar return.”
The aforementioned “lakes” are near vast dune fields in Titan’s southern and northern latitudes. However, rather than liquid, there is a distinct probability that infrared reflections detected by Cassini bounced off a hard, glassified crust left by an interplanetary plasma discharge.
That the Solar System was the scene of catastrophic encounters between charged bodies in the recent past is a principle tenet of Electric Universe theory. Electric fields and their associated lightning bolts caused orbital variations and geological upheavals among planets and moons. Cometary bodies scaling down in size from something as big as Venus to particles in Saturn’s rings, might be forensic evidence for those events.
Based on the presupposition that those ideas have merit, and that Venus could be a new addition to the Solar System, why not apply the same theory to Titan? If Titan is a relatively new addition to Saturn’s system of some 60 moons, then the fact of its methane atmosphere does not indicate replenishment, but youth.
According to a recent press release, scientists found “negatively charged molecules” in Titan’s atmosphere. Those negatively charged carbon ions are, as the article states, “… surprising because they are highly reactive and should not last long in Titan’s atmosphere…” Thus, the finding is “…completely reshaping current understanding of the hazy moon’s atmosphere.”
If, like Venus, Titan is not a wizened denizen of an even more ancient Solar System, but, instead, is a new member of a remodeled system, then new ways of describing it must be considered.
Wal Thornhill again:
“We must therefore allow that Venus and Titan may both have new surfaces if planets and moons are not formed through accretion by impacts billions of years ago. The ‘befuddlement’ and ‘mystery’ may prove to be the result of an unquestioned belief in that [billions-of-years-ago] hypothesis. Predictions based on that story have had no success in the space age. So we may be confident that planets did not accrete from a solar nebula.”
Those concepts are never reported in the conventional press. If they do come up in a comments section or a blog, they are mocked or banned. Although, when the time for changes in thought arrives, those changes are inevitable. When reasonable people apply elements of electrical theory to observations that otherwise provoke confusion, there will be more clarity of perception. Observations do not create new theories, observations are inserted into theories.
Electric Universe theory establishes a more comprehensive picture when data from space probes and telescopes are inserted into it. It is not considered viable in consensus circles due to its timeframe. Among its opponents is the foregone conclusion that the Solar System is as it was since it formed billions of years ago. To consider a reordering less than 10,000 years ago is blasphemy. Fortunately, it is a well-established pattern that what once was heresy will often evolve into convention. | 0.854991 | 3.977932 |
In major cities such as Metro Manila and Metro Cebu, the dark skies peppered with glittering stars are practically nonexistent and often overlooked. In fact, night skies and stars are hardly appreciated in the city. After all, metropolitan cities are often bright with lights themselves– insomuch that stars in the sky look like nothing more than mere specks of dust to city dwellers.
Indeed, in cities beleaguered with light pollution, Mother Nature’s work often takes the backseat while the artificial lights around the city dance around. As a result, stargazing is practically impossible to do. Considering that stargazing in cities besieged by light pollution already poses a challenge by itself, it becomes almost impossible to capture any decent image of the night sky and the stars with a camera. In this regard, executing astrophotography shots in the city is not exactly a feasible idea. Luckily, events such as the annual Earth Hour where people are encouraged to unplug for an hour (and when the surroundings are dark enough to expose the stars we often overlook) allow us a moment’s reprieve from the light pollution. However, even then, it can be quite difficult for astrophotographers to take worthy shots of the night sky. With this in mind, they would be constrained to look for places all over the Philippines with minimal to no light pollution at all. Read on below to see the top places for astrophotography in the Philippines.
VISUAL ASTRONOMY VS PHOTOGRAPHIC ASTRONOMY
In a nutshell, the main difference between visual astronomy and photographic astronomy is that the former is basically just gazing at the stars whereas the latter involves the capturing of still or moving images of objects in the night sky.
Long ago, all of astronomy was based solely on visual observations only making it a bit challenging to chart planetary movements, constellations and star locations. In fact, history is fraught with notes and sketches from the patient and determined work of dedicated astronomers such as Kepler, Galileo and the Herschel’s. It was not until 1840 where the first successful astrophoto was released. It was an image of the moon captured by Louis Jacques Mande Daguerre. However, while it took him twenty minutes to expose, it was not much to look at.
As time progressed, technological innovations were made to increase the capturing power of the camera. In this regard, individuals with an affinity for the night sky have beefed up their gears. As a result, astrophotography has become a leisurely activity or hobby but more importantly, it revolutionized the scientific understanding of the universe the moment it was introduced. If not for it, the sky would not have been mapped out completely.
THE TOP ASTROPHOTOGRAPHY SPOTS IN THE PHILIPPINES
WK Forest Reserve and Campgrounds (Tanay, Rizal)
Nestled deep in the mountains of Tanay is WK Forest Reserve and Campgrounds, one of Rizal’s best-kept secrets. It is one of the latest campsites in Tanay, Rizal and is a favorite among 4X4 enthusiasts. The camp is very secluded (seeing as it can only be traversed by a 4X4 vehicle, hiking or a motorbike) ensuring that you get a magnificent view of the night sky. WK Forest Reserve and Campgrounds has three types of campsites (Open, Forest and Overlooking Camp) with the Open Camp being the most feasible for stargazing and astrophotography.
Mt. Gulugod Baboy (Mabini, Batangas)
Climbing Mt. Gulugod Baboy is pretty much like a journey underneath a blanket of stars. Apart from the intriguing name, Mt. Gulugod Baboy is said to offer an expansive view of the sea from its mountaintop. In fact, apart from being a popular place for stargazing and astrophotography, Mt. Gulugod Baboy is an ideal campsite for individuals who just wish to enjoy scenic views.
While largely a beach hotspot, Batangas is one of the best places in Luzon for stargazing. In lieu of a beach getaway such as in Calatagan and Tali, head to Laiya. It is one of the few places in Batangas that remains mostly untouched and allows the beach-goers a semblance of peace in a starlit place. As the place has no active nightlife, it is an excellent place for stargazing and astrophotography.
Cagbalete Island mostly consists of beach spots considering that it has a shoreline with powdery white sand. However as the vibe of the island is laidback and as there are a lot of secluded spots, it is one of the ideal spots in the Philippines for stargazing and astrophotography.
Cloud 9 Boardwalk (Siargao)
Siargao is mainly a place for beach lovers and surfers who love the tropical lifestyle. Cloud 9 Boardwalk, one of its hotspots, attracts both beach enthusiasts and surfers. However, the place is quite magical at night as the night sky becomes clearer and the stars more evident. As this part of Siargao only has a handful of lights peppered around the place, it is the perfect spot for both stargazing and astrophotography.
Zambales is rife with places ideal for astrophotography and stargazing. Even its well-known coves and hotspots such as the Nagsasa Cove are places feasible for capturing images of the night sky. What makes Nagsasa Cove so magical is that you can lie down by the shores and just delight in the heavenly bodies above as you drift to sleep. Alternatively, if you do not wish to suffer-through a boat ride, then consider Pundaquit in Zambales as an alternative. The place offers a few homestays in their coastal community and by dusk, you can revel in the wonder of the night sky filled with a billion stars.
Tinalisayan Island (Masbate)
One of the lesser-known beach hotspots in the Philippines is Tinalisayan Island in Masbate. Owing to its anonymity, few travelers ever go here and it has remained virtually untouched. As a result, it is one of the most beautiful places in the country. With the stunning and velvety ivory sandbar, the view is incredibly breathtaking by the time the sun settles and the moon takes over. Just imagine how it would look with the milky-way galaxy in the vast skies.
Mount Pulag (Benguet)
Mount Pulag is one of the most famous campsites in the Philippines—and for good reason. With the cool weather and awe-inspiring views, who could resist a visit to the place? It is truly one of the most beautiful destinations in the country and is worth a spot on your bucket list. As the country’s third-highest peak, Mount Pulag offers a view unlike any other. It has one of the most stunning scenes of the night sky making it a premier spot for astrophotography and stargazing—certainly a rewarding feat after a grueling climb!
Calaguas Island (Camarines Norte)
Located in the province of Camarines Norte, Calaguas Island is an island that allows you to explore heaven on earth. Apart from the tranquil and serene vibe, a magnificent night sky awaits its visitors. In Calaguas, visitors can enjoy a myriad of activities from swimming to stargazing and astrophotography.
Dubbed as the most cinematic place you will ever see in the Philippines, Batanes is a visual delight whether it is day or night. Apart from its remoteness, Batanes is ideal for stargazing and astrophotography owing to its proximity away from large cities as well as the scarcity of artificial lighting on the small island. Here, visitors are lucky enough to see the Milky Way sky—something that cannot be appreciated in cities.
The Philippines, albeit peppered with major cities fraught with light pollution, still has an abundance of places that offer travelers a glorious and scenic view of the night sky. So, if you have ever wondered how the night sky looks in its plain glory, pack your bags and take a trip to one of the places enumerated above. Oh, and to commit the trip to memory, bring your camera with you and snap a shot of the night sky that is never visible in the cities.
For your camping needs and essentials, shop at Philippine Camping Gears Online Shop. | 0.805044 | 3.445206 |
Turns out there is something new under the Sun, at least to us; on Tuesday, April 26 scientists announced the discovery of a new moon in the Solar System—but it’s not around Earth, or Jupiter, or Saturn, or any of the planets that you’ve long been familiar with. This new moon is orbiting a distant world even farther away and smaller than Pluto: the dwarf planet Makemake (pronounced mah-kay mah-kay), located deep in the Kuiper Belt and currently over 52 times farther away from the Sun than we are.
Makemake itself was only discovered a little over a decade ago in observations from the Palomar Observatory on March 31, 2005 and announced to the public along with larger dwarf planet Eris on July 29 of the same year. It’s a relatively bright 870-mile-wide world coated, like its larger cousin Pluto, in methane and nitrogen ices. The reason it’s taken this long to identify the first satellite around it is that the moon — currently designated S/2015 (136472) 1 and nicknamed MK 2 — is 1,300 times dimmer than Makemake and only about 100 miles (160 km) across, and isn’t always in a convenient location to be spotted.
“Our preliminary estimates show that the moon’s orbit seems to be edge-on, and that means that often when you look at the system you are going to miss the moon because it gets lost in the bright glare of Makemake,” said Alex Parker of the Southwest Research Institute in Boulder, Colorado, who led the image analysis for the observations.
The telling images for the discovery of MK 2 were obtained with Hubble’s Wide Field Camera 3 in April 2015.
According to Alex on Twitter this discovery means all of the known Kuiper Belt dwarf planets — Pluto, Eris, Haumea, and now Makemake — have moons.
More follow-up observations with Hubble will be needed to determine the orbital characteristics of MK 2. At its distance from Makemake — about 13,000 miles, or 21,000 kilometers — if its orbit is circular it likely completes a single one at least every 12 days.
Learning the shape of MK 2’s orbit will also tell us how it was acquired; if its orbit is circular it’s likely the result of a collision, if highly elliptical or eccentric it’s probably a captured KBO.
By my count this discovery brings the total number of known natural satellites in the Solar System up to 464, including asteroids and trojans with moons (but not ring systems.) There’s 58 times more moons in the Solar System than there are official planets!
Watch a brief video about the discovery from NASA’s Goddard Space Flight Center below: | 0.85867 | 3.834376 |
Deep Crustal Heating by Neutrinos from the Surface of Accreting Neutron Stars
We present a new mechanism for deep crustal heating in accreting neutron stars. Charged pions () are produced in nuclear collisions on the neutron star surface during active accretion and upon decay they provide a flux of neutrinos into the neutron star crust. For massive and/or compact neutron stars, neutrinos deposit of heat per accreted nucleon into the inner crust. The strength of neutrino heating is comparable to the previously known sources of deep crustal heating, such as from pycnonuclear fusion reactions, and is relevant for studies of cooling neutron stars. We model the thermal evolution of a transient neutron star in a low-mass X-ray binary, and in the particular case of the neutron star MXB 1659-29 we show that additional deep crustal heating requires a higher thermal conductivity for the neutron star inner crust. A better knowledge of pion production cross sections near threshold would improve the accuracy of our predictions.
pacs:25.40.Qa, 25.40.Sc, 26.60.Gj, 26.60.Kp, 97.60.Jd
Neutron stars in X-ray binaries accrete matter from their companion stars. As matter accretes, the crust is continually compressed and undergoes a series of non-equilibrium nuclear reactions such as electron captures, neutron emissions and pycnonuclear fusion reactions that release per accreted nucleon Bisnovatyĭ-Kogan and Chechetkin (1979); Sato (1979); Haensel and Zdunik (1990, 2003, 2008). Energy release mainly occurs in the inner crust at mass densities between and is referred to as deep crustal heating. During an accretion outburst, deep crustal heating brings the entire crust out of thermal equilibrium with the core. When accretion ends and the neutron star enters quiescence, crust cooling powers an observable X-ray light curve Ushomirsky and Rutledge (2001); Rutledge et al. (2002); Shternin et al. (2007). Thermal evolution models of accreting neutron stars that include deep crustal heating successfully reproduce most observed quiescent X-ray light curves Brown and Cumming (2009). The cooling light curves of several sources, however, require an additional heat deposition in the outer crust during outburst to reach observed quiescent temperatures Cumming et al. (2006); Deibel et al. (2015). The source of extra heating remains unknown, but must be comparable in strength to the heat release from non-equilibrium nuclear reactions.
Here we discuss a new source of heating in neutron star crusts from the decay of charged pions on the neutron star surface. The neutron star’s strong gravity accelerates incoming particles to kinetic energies of several hundred MeV per nucleon before they reach the neutron star surface. The accreted matter, usually consisting of hydrogen or helium, undergoes nuclear collisions with the nuclei on the neutron star surface. Nuclear collisions produce pions, in particular , that upon decay emit a flux of neutrinos. Approximately half of these neutrinos carry their energy into the crust, where they experience multiple scatterings and are eventually absorbed in the inner crust. This neutrino heating provides an additional source for deep crustal heating. In this work we present the first calculations of deep crustal heating by neutrinos from the decay of stopped pions on the surface of neutron stars.
The paper is organized as follows. In Section II we develop the formalism required to discuss the energy deposition by neutrinos from the stopped pion decays. We will first briefly review the main mechanism of deep crustal heating by neutrinos in II.1. Following this discussion, we review the main steps involved in calculating the energy deposited from pion production on the surface of neutron stars in II.2. This section is closed by discussing at what depth in the crust neutrinos will deposit their energy in II.3. We then proceed to Section III to display the results of our calculations using various equations of state (EOS) as well as pion production in three possible nuclear collisions. This section ends with a discussion of the observational implications of deep crustal heating in understanding cooling light curves of neutron stars in X-ray transients. Finally, in Sec. IV we offer our summary and conclusions.
ii.1 The Main Mechanism
Neutron stars in low-mass X-ray binaries typically accumulate hydrogen-rich or helium-rich matter from the surface of their companions in an accretion disk that is later accreted onto the neutron star surface during an accretion outburst. During outburst, the incoming particles collide with the nuclei on the neutron star surface Bildsten et al. (1992) and can produce pions if the particle’s kinetic energy is above the pion production threshold of . Neutral pions decay almost instantaneously via releasing their energy at the surface. Neutrinos from the decay of negative pions may be strongly suppressed because are often absorbed, via strong interactions, before they can undergo a weak decay. Positively charged pions slow down and stop near the neutron star surface and decay into muons and muon neutrinos through . This produces monoenergetic muon neutrinos, , of energy MeV. The anti-muon subsequently decays through on a muon-decay time scale of , with a well-determined neutrino energy spectrum Scholberg (2006). Approximately half of the neutrinos produced escape the neutron star and the other half move into the crust carrying a total energy of
per accreted nucleon, where is the total number of ’s produced per accreted nucleon. In addition to gravitational acceleration, accreting particles may undergo electromagnetic acceleration in the strong electric and magnetic fields that are likely present. This could significantly increase pion and neutrino production, but we will explore this in later work.
ii.2 Pion Production per Accreted Nucleon
We now calculate the number of charged pions produced from infalling matter. Assuming that the infalling matter has zero velocity at infinity (free-falling), we estimate the kinetic energy of the accreted matter at the surface of the neutron star Bildsten et al. (1992) using
where is the Schwarzschild radius, is the mass of the infalling particle, and and are the neutron star mass and radius, respectively. If the kinetic energy of the incoming particles is sufficiently large, they will collide with the nuclei on the surface of the neutron star and can produce pions. The multiplicity of pion production, defined as the number of pions produced per collision event, strongly depends on the initial kinetic energy of the incoming particle as well as on the target nuclei that is composed of the mixture of light-to-medium nuclei. Since both incoming protons and -particles are charged particles, before they undergo a hard nuclear collision they partially lose energy due to interaction with atmospheric electrons. The energy loss of charged particles can be calculated using the Bethe-Bloch equation
where MeV mol cm, is the charge number of the incident particle (projectile), is the atomic number of the target, is the atomic mass of the target in g mol, , is the relativistic Lorentz factor, is the mean excitation energy in eV, and is the density effect correction to ionization energy loss, which is negligible for energies under consideration. Here
is the maximum kinetic energy which can be imparted to a free electron in a single collision. A complete description of the electronic energy loss by heavy particles can be found in Chapter 32 of Ref. Amsler et al. (2008). A similar study of the incident-beam particles deceleration through repeated Coulomb scatters from atmospheric electrons was also carried out in Ref. Bildsten et al. (1992). The energy of the particle that undergoes a hard nuclear collision is therefore
where is the strong interaction mean free path, is the number density of scattering centers, and is the strong collision cross section. Note that the energy loss depends on the initial beam energy through Lorentz parameters. Therefore, Eqn. (5) takes an exact form if one replaces with , where , and solves the equation
iteratively for all -values. The probability density function for the interaction of a particle after traveling a distance in the medium is given by Tavernier (2010)
If the incident beam energy per nucleon during hard collision is above the threshold energy of MeV pions are produced. The pion production multiplicity, , depends greatly on the kinetic energy of the incident particles as given by Eqn. (6). Here is the pion production cross section, whereas is total reaction cross section. We discuss in Sec. III. The total number of pions produced per infalling particle can be calculated as
where is the range, or the maximum possible distance the incoming charged particle can penetrate the matter before losing all its kinetic energy through electromagnetic energy loss.
ii.3 Optical Depth and Deep Crustal Heating
The neutrinos moving into the neutron star crust are first scattered and/or absorbed at mass densities which can be determined by the neutrino transport optical depth
where () is the neutrino-ion (neutrino-free neutron) transport cross section, is the ion number density in the crust, is the number of nucleons in the unit cell, is the number density of free neutrons, and is the number of free neutrons in a unit cell. The transport cross section is defined as
with the free-space differential cross section for neutrino-nucleon elastic scattering given by Horowitz (2002)
where is the scattering angle, is the incoming neutrino energy, is the vector coupling constant, and is the axial vector coupling constant. The neutrino-ion elastic scattering differential cross section is
where is the total weak charge of the ion with and , is the ground state elastic form factor of the ions, and is the four momentum transfer squared.
Notice that both and are functions of the neutrino energy. The neutrino energy spectrum from stopped pions is well known Scholberg (2006). To determine the neutrino-ion and neutrino-free neutron elastic scattering cross sections we use the root-mean-square neutrino energies calculated as
where is the neutrino flux with energy . In particular, we use the root-mean-squared values of and for electron and muon neutrinos, respectively (see Eqn. (1)) and .
By definition, represents the number of mean free paths for the neutrino traveling from the surface of the star at to some inner depth . Neutrinos are first scattered (absorbed) at a depth of corresponding to . We assume neutrinos are eventually absorbed near this optical depth. Electron neutrinos are most likely absorbed in the crust via inelastic neutrino charged current interactions, whereas muon neutrinos deliver most of their energies through muon neutrino-electron scatterings, and may leave the star once their energy is low corresponding to the large neutrino mean free path. The energy of as given by the Eqn. (1) is therefore delivered to the crust at depth of .
iii.1 Equations of State of Neutron-Star Matter
The equation of state adopted in this work is composed of several parts. Matter in the outer crust of the neutron star is organized into a Coulomb lattice of neutron-rich nuclei embedded in a degenerate electron gas. The composition in this region is solely determined by the masses of neutron-rich nuclei in the region of and the pressure support is provided primarily by the degenerate electrons. For this region we adopt the equation of state by Haensel, Zdunik and Dobaczewski (HZD) Haensel et al. (1989). The inner crust begins at the neutron-drip density of . The EOS for the inner crust at mass densities is, however, highly uncertain and must be inferred from theoretical calculations. In addition to a Coulomb lattice and an electron gas, the inner crust now includes a dilute vapor of quasi-free neutrons. Moreover, at the bottom layers of the inner crust, complex and exotic structures with almost equal energies referred to as “nuclear pasta” have been predicted to emerge Ravenhall et al. (1983); Hashimoto et al. (1984); Lorenz et al. (1993). For this region we use the EOS by Negele and Vautherin Negele and Vautherin (1973). The inner crust ends at a mass density near , beyond which the neutron star matter becomes uniform. For this uniform liquid core region we assume two equations of state that cover a wide range of uncertainties that currently exist in the determination of the equation of state of nuclear matter at normal and supra nuclear densities:
The relativistic mean-field model by Chen and Piekarewicz Chen and Piekarewicz (2014) (FSU2), whose parameters were calibrated to reproduce the ground-state properties of finite nuclei and their monopole response, as well as to account for the maximum neutron star mass observed to date Demorest et al. (2010); Antoniadis et al. (2013). Due to the lack of stringent isovector constraints, the original FSU2 predicts a relatively stiff symmetry energy of MeV with density slope of MeV. It is known that by tuning two purely isovector parameters of the RMF model one can generate a family of model interactions that have varying degrees of softness in the nuclear symmetry energy without compromising the success of the model in reproducing ground-state properties Horowitz and Piekarewicz (2001); Fattoyev et al. (2012). Following this scheme we tuned the purely isovector parameters of the FSU2 model to get MeV and MeV and refer to this model as the FSU2 (soft).
The soft and stiff equations of state that agree with the lower and upper limits of the EOS band derived from microscopic calculations of neutron matter are based on nuclear interactions from chiral effective field theory by Hebeler et al. Hebeler et al. (2010) (HLPS). Notice that the symmetry energy parameters in this model are MeV and MeV.
A recent survey on the mass spectrum of compact objects in X-ray binaries from 19 sources shows that their masses can be anywhere in the range of Casares et al. (2017). Note that stars made with stiff equations of state can accelerate particles to near the pion-production threshold, whereas those with soft equations of state allow particles to gain kinetic energies significantly larger than the pion-production threshold even for low-mass neutron stars.
iii.2 Production of in -, - and - Collisions
Charged pion production from the interaction of proton beams with some selected nuclei have been measured at incident energies of 585 MeV Crawford et al. (1980), 730 MeV Cochran et al. (1972), as well as at 800 and 1600 MeV Denes et al. (1983); Lemaire et al. (1991). Inclusive pion production at lower incident energies of 330, 400, and 500 MeV from proton-nucleus collisions ( and ) nuclei have also been measured. However, measurements of pion production cross sections at medium beam energies for proton-nucleus collisions are still incomplete. On the other hand, the surface composition of neutron stars remains an outstanding problem Chang et al. (2010). For accreting neutron stars, the upper layer is likely composed of lighter elements such as hydrogen or helium, depending on the composition of accreted material from the companion star. For the sake of simplicity, instead of a range of target nuclei, we assume only two types of the target nuclei: protons and .
Based on the available experimental data Ref. Burman et al. (1990) performed a Monte-Carlo simulation to evaluate the total pion production cross sections at various proton beam energies on selected nuclei. Using these Monte-Carlo data and the - reaction cross sections we estimated pion multiplicities for - collision at incident beam energies above 325 MeV, see Fig. 1. Note that the pion production cross section in Monte-Carlo simulations is assumed to go to zero at energies below 325 MeV Burman et al. (1990). It is important to mention, however that pions can be produced at subthreshold energies via the excitation and decay of -resonances (See Ref. Tsang et al. (2017) and references therein). The Fermi motion of nucleons in nuclei can also greatly enhance the pion production cross sections in the vicinity of the threshold energy Bertsch (1977); Sandel et al. (1979). Despite efforts to measure subthreshold pion production in the past (See, Ref. Miller et al. (1993) and references therein), regrettably, experimental data on this front still remains incomplete.
In the case of accreting hydrogen the - collision becomes an interesting case Bildsten et al. (1992, 1993) to study pion production. Fortunately, there are sufficient experimental data available on the pion production in collisions. Using the experimental data from Daehnick et al. (1995); Hardie et al. (1997); Flammang et al. (1998); Schwaller et al. (1979) we plot the multiplicity of pion production as a function of the proton beam energy from the - collisions (see Fig. 1). The current experimental error-bars are in the order of 25% for most of these measurements, except for few cases when beam energies are in the range of MeV, the relative error-bars are as large as 80%.
On the other hand, experimental measurements of pion production in in - collisions are still missing. For this we use the isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model Li (2002a, b) to calculate multiplicities at various incident beam energies per nucleon and impact parameters. In this model all subthreshold pions are produced from decays of low-mass (1232) resonances formed in nucleus-nucleus inelastic collisions. While the pion production cross sections drop sharply when the energy per nucleon is below threshold, there is an appreciable pion production cross section at incident beam energies as low as 150 MeV per nucleon mostly due to Fermi motion of nucleons in . Note that pion production in heavy-ion collisions depends on the EOS and the ratio of charged pions on the nuclear symmetry energy used. In this exploration study, we use a momentum-independent potential corresponding to a stiff EOS with MeV and a symmetry energy that is linear in density. In Fig. 2 we plot multiplicities as a function of the incident beam energies per nucleon for subthreshold energies. In our calculation for - collisions, we use multiplicities averaged over the impact parameter , whose dependence is plotted in Fig. 3. For head-on collisions with the pion-production cross section is obviously much larger. In generating these data we run events for most cases, except for low incident energies, where we used up to events to have a better statistics. The statistical error-bars for these simulations are . It is worth noting that the model dependence on the EOS and the density dependence of the symmetry energy is of the same order as the statistical errors quoted above. The detailed model dependencies near the pion production threshold are addressed in Ref. Li (2015).
iii.3 Neutrino Energy Deposition in the Inner Crust
We now calculate the total energy carried by neutrinos into the inner crust. In Table 2 we present results for a and for a (in square brackets) neutron star and the four equations of state discussed in the text. In Fig. 4 we display the full results as a function of the neutron star mass for soft equations of state only. As is evident from Table 1, low-mass neutron stars can only accelerate the infalling matter to energies of about the pion-production threshold. Therefore the result is highly sensitive to the pion production cross section around threshold energies. This result calls for improved experimental measurements of pion production in proton-proton collisions, as well as for pion production in - and - collisions for beam energies per nucleon in the range of to MeV.
Moreover, there is a strong sensitivity of the pion production to the equation of state employed in determination of stellar structure. In particular, if the equation of state is very stiff—such as the HLPS (stiff)—then even for a neutron star the incoming particles are not accelerated enough to produce pions (See Tables 1 and 2). On the other hand, if the equation of state is soft, then for a neutron star the energy deposited by neutrinos can be as large as MeV per accreted nucleon. The result is more pronounced if helium is being accreted onto the surface of neutron star, mainly because the IBUU simulations suggest that a substantial amount of pions can be produced at subthreshold beam energies.
We also investigate the impact of the neutron star’s compactness, with compactness defined as . For example, while stars built with the HLPS (stiff) equation of state may not accelerate the infalling matter to high kinetic energies for low-mass stars, it can certainly do so for very massive neutron stars. In particular, for a , the total energy deposit is MeV, when -Fe (-Fe) collisions take place at the surface. To cover all possible equations of state in Fig. 5 we plot the result as a function of the compactness.
We find that the heat deposition from neutrinos is comparable with other previously known sources of deep crustal heating such as from pycnonuclear fusion reactions. In Table 3 we present our results for the more interesting cases of soft equations of state only, where is significant even for moderate-mass neutron stars. Depending on the mass of the star and the EOS used, the energy of is delivered to the regions of the inner crust where mass densities are of order to . For example, for a neutron star this would correspond to mass densities of in units of , or equivalently to baryon densities of , where g cm is the nuclear saturation density.
Table 3 assumes that half of the neutrinos produced from the decay of stopped pions travel radially inward. In reality, the decay is isotropic and therefore it is worth to analyze the location of heat delivery as an angle of incidence of neutrinos. The fraction of the number of neutrinos within a cone with apex angle to the total number of neutrinos is equal to . Here corresponds to the angle of incidence in the radial direction, whereas corresponds to the direction horizontal to the surface. In Fig. 6 we display the location of heat deposition as a function of for a neutron star using HLPS (soft) EOS. The result shows that most of neutrinos are delivered to the deep region of the crust, and only a small fraction of them scatter at shallower regions.
Note that in our calculations above we did not take into account additional redshift effects as neutrinos go deeper into the crust. The effective neutrino energy should slightly increase due to the gravitational redshift by a factor of , where is the local gravitational potential Thorne (1977). However our calculations show this effect is because the crust is thin.
iii.4 Observational Implications
Cooling neutron stars
Non-equilibrium nuclear reactions during active accretion heat the neutron star crust out of thermal equilibrium with the core. When accretion stops, the crust cools toward thermal equilibrium with the core Brown et al. (1998); Ushomirsky and Rutledge (2001); Rutledge et al. (2002); Cackett et al. (2008). Crust cooling is observed as a quiescent X-ray light curve, with one of the most well studied examples being the cooling transient MXB 1659-29 Brown et al. (1998); Ushomirsky and Rutledge (2001); Cackett et al. (2008); Brown and Cumming (2009). Cooling observations at successively later times into quiescence probes successively deeper layers in the crust with increasingly longer thermal times Brown and Cumming (2009). In particular, it was shown that about a year into quiescence the shape of the cooling light curve is sensitive to the physics at mass densities greater than neutron drip corresponding to the inner crust Page and Reddy (2012). This suggests that cooling light curves of neutron stars in low-mass X-ray binaries one-to-three years after accretion outbursts should be sensitive to the additional deep crustal heating by neutrinos Brown and Cumming (2009).
Comparing our results with the heat released from pycnonuclear fusion reactions Haensel and Zdunik (2008) we notice that not only are they of the same order, but also the heat is deposited in the same density regions (crust layer). Subsequently we calculated the column depths where neutrinos are first scattered, Brown and Cumming (2009). Here is the local pressure and is the local gravitational acceleration defined as Thorne (1977)
We find that the column depth values lie in the range of (See Table 3). Since the amount of heat deposited for massive stars is comparable to the heat released from pycnonuclear reactions, the observation of cooling light curves, in particular, could be used to help distinguish massive stars from the low-mass stars.
To analyze the sensitivity of crustal heating by neutrinos on the
cooling curves, we simulate the thermal evolution of a neutron star crust using the thermal evolution
dStar Brown (2015), which solves the general
relativistic heat diffusion equation. The detailed microphysics of
the crust is discussed in Ref. Brown and Cumming (2009) and the
parameters of the cooling model are described in
Ref. Deibel et al. (2017). In particular, this model assumes an
impurity parameter of throughout the crust,
which is defined as
where is the number density of the nuclear species with number of protons, and is the average proton number of the crust composition.
In Fig. 7 we display the crust cooling curves for four possible cases. The solid black curve corresponds to the case without heat deposition from neutrinos in the inner crust with . The red dashed curve corresponds to the case when a MeV per accreted nucleon heat source is deposited at density regions of . The crust temperature is marginally increased by the neutrino heating because most of the additional heat is transported into the core.
We then examine two cases, with and without neutrino heating, but including a nuclear pasta layer in the inner crust. It is expected that nuclear pasta forms at densities above corresponding to the bottom layers of the inner crust. The thermal conductivity of nuclear pasta could be small, corresponding to a large impurity parameter Horowitz et al. (2015). The black short-dashed curve shows the case of no neutrino heating, but at densities of corresponding to nuclear pasta. Finally, in blue dash-dotted line we display a cooling curve that includes both nuclear pasta and the heat depositiion from neutrinos. The crust temperature is higher in these two cases, because the low thermal conductivity of the nuclear pasta layer prevents a large portion of heat from diffusing into the core.
As evident from Fig. 7, the additional heat source can make a noticeable change in the cooling light curves. The cooling rate depends on many other factors and in particular strongly depends on the crust thickness, which is usually small for massive stars. Moreover, as illustrated in Fig. 7 the low thermal conductivity corresponding to the nuclear pasta can strongly affect thermal diffusion time maintaining a temperature gradient between the neutron star’s inner crust and core for several hundred days into quiescence Deibel et al. (2017). Note that all of the above models use the same pairing gap model of neutron superfluid in the singlet state with the critical temperature profile given by Schwenk et al. Schwenk et al. (2003). We have also tested other superfluid pairing gap models, such as the one by Gandolfi et al. Gandolfi et al. (2008), and the results are qualitatively similar to Fig. 7.
Crust cooling in MXB 1659-29
As described above, neutrino deep crustal heating will noticeably increase the crust temperature and the shape of the cooling light curve. Here we investigate the impact of extra heating from neutrinos on the particular case of MXB 1659-29 that entered quiescence after an accretion outburst Wijnands et al. (2003, 2004) and cooled for before entering outburst once more Negoro et al. (2015). The late time cooling observations probe the thermal properties of the inner crust and make MXB 1659-29 an interesting test case for neutrino heating.
Our thermal evolution model of MXB 1659-29 uses a and neutron star at the observed outburst accretion rate of . The model includes a per accreted nucleon shallow heat source between and , consistent with the findings from Brown and Cumming (2009). Using a model without nuclear pasta, the cooling light curve is fit with an impurity parameter for the entire crust of and the S03 pairing gap Schwenk et al. (2003). We then test representative values of neutrino heating: and per accreted nucleon. As can be seen in Fig. 8, the model fit with becomes inconsistent with the observational data once neutrino heating is added to the inner crust. In order to reestablish a fit, the crust impurity parameter must be lowered to (corresponding to a higher crust thermal conductivity) as increases.
Alternatively, the cooling of MXB 1659-29 may be fit with a nuclear pasta layer in the crust if the G08 pairing gap model is used Gandolfi et al. (2008), as we demonstrate in panel (b) of Fig. 8. In this case, the low thermal conductivity of the nuclear pasta maintains a higher crust temperature during quiescence and a layer of normal neutrons forms at the base of the crust Deibel et al. (2017). Without neutrino heating, the cooling observations of MXB 1659-29 are fit with a crust impurity of and a pasta impurity parameter of . We find that, similar to the model without nuclear pasta, as neutrino heating is increased in the inner crust, the pasta impurity parameter must decrease to reestablish a fit to the observations.
Note that the cooling of MXB 1659-29 may be fit with other neutron star masses and radii Brown and Cumming (2009) and the results in Fig. 8 are for a fixed neutron star gravity (and crust thickness). Cooling light curve shapes are degenerate in several parameters, for example: the neutron star gravity, the crust impurity parameter, and the mass accretion rate. Because the effect of neutrino heating is difficult to delineate from the effects of other model parameters we therefore can not determine if neutrino heating is present during outburst. It is worth noting, however, that if deep crustal heating from neutrinos is present then existing constraints derived from cooling light curves will need to be revisited, likely requiring a higher crust thermal conductivity or a different neutron star gravity.
Iv Conclusion and Outlook
We presented a new mechanism of deep crustal heating of neutron stars in mass-transferring binaries by neutrinos that are decay remnants of charged pions produced at the surface of neutron stars. Our calculations showed that massive and compact stars can accelerate infalling matter to energies substantially larger than the pion-production threshold resulting in ample generation of neutrinos. Approximately half of these neutrinos travel into the inner crust and deposit per accreted nucleon for massive and compact stars.
The deep crustal heating from neutrinos is comparable in strength to pycnonuclear fusion reactions and other non-equilibrium nuclear reactions taking place during active accretion. Additional deep crustal heating will affect the cooling light curves of accreting neutron stars at late times into quiescence. The effect is most pronounced when the star is massive and might help distinguish high-mass stars from low-mass stars. In general, for a fixed neutron star gravity we find that additional deep crustal heating requires a higher thermal conductivity for the crust and the crust impurity parameter must be lowered. In the particular case of MXB 1659-29, for a model without nuclear pasta and the S03 pairing gap, is required if any neutrino heating is added. For a model with nuclear pasta and the G08 pairing gap, for nuclear pasta is needed if neutrino heating is present.
Our calculation of pion production assumes that the incoming protons are slowed by Coulomb collisions with atmospheric electrons Zel’dovich and Shakura (1969). Plasma instabilities or a collisionless shock may instead stop the proton beam (e.g. see Ref. Shapiro and Salpeter (1975)), reducing the rate of nuclear collisions. In addition, depending on the accretion geometry, the incoming particles may not have the full free-fall velocity, e.g. in disk accretion if the disk reaches all the way to the neutron star surface. Neutrino heating may operate only with a quasi-spherical accretion flow or if the neutron star lies within the last stable orbit (e.g. see discussion in Ref. Bildsten et al. (2003)).
There is also a strong sensitivity of our results to the pion production cross sections at near threshold energies. Pion production may play a significant role in stellar environments and in particular, a better knowledge of pion production cross sections in -, -, -, and - collisions for beam energies - MeV/nucleon may help to better understand the structure and transport properties of neutron star crusts from cooling observations.
Acknowledgements.We thank Professors Hans-Otto Meyer, Hendrik Schatz, and Rex Tayloe for many helpful discussions. FJF, CJH, and ZL are supported by the U.S. Department of Energy (DOE) grants DE-FG02-87ER40365 (Indiana University), DE-SC0008808 (NUCLEI SciDAC Collaboration) and by the National Science Foundation through XSEDE resources provided by the National Institute for Computational Sciences under grant TG-AST100014. EFB is supported by the US National Science Foundation under grant AST-1516969. AC is supported by an NSERC Discovery Grant and is a member of the Centre de Recherche en Astrophysique du Quebec (CRAQ). BAL is supported by the U.S. Department of Energy, Office of Science, under Award Number DE-SC0013702 (Texas A&M University-Commerce) and the National Natural Science Foundation of China under Grant No. 11320101004.
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This is is perhaps one of the most important teapots in astronomy, it’s the teapot used to brew and serve tea during Cambridge’s Institute for Astronomy tea breaks. Much of scientific research in the UK is fuelled by the consumption of large amounts of tea, and the tea break is an an important ritual in research life there. In fact, one of my first experiences in astronomy was as a work-experience student at the Armagh Observatory sometime in the 1980s. I was most impressed by the tea-break! I never saw so many people together discussing such obscure and interesting topics. I think that was the moment I realised that I wanted to be an astronomer.
After writing about telescopes in space in my last article, I was reminded of this “illustrated interview” of Howard Grubb, published in the Strand Magazine in 1896. It starts perhaps not very promisingly: “The poverty of Ireland is such that the superficial observers are apt to wonder whether any good thing can really come out of that distressful country”. It does improve from there! It was sent to me by a descendant of Grubb. It is very interesting, especially the part at the end about future large telescopes which, of course, will be floating in water. The image below is supposed be “casting the mirror for the great Melbourne telescope” but it doesn’t look like any kind of “astronomical” ceremony to me!
Read the PDF here:
The Euclid space mission (which I have already written about here) plans to stringently test our cosmological model by precisely measuring the shapes and positions of a billion faint galaxies. But you are not going to take pictures of each galaxy individually, obviously, that would be too slow! You need to do a survey, which means with each image you want to take a picture of largest possible area of the sky. So, you need a survey telescope, and because you have a limited budget you need to be able to launch your telescope on the smallest possible rocket. How do you do this? That is what I am going to write about here.
Designing survey telescopes has always been challenging. Photographic plates made possible for the first time measuring the positions and brightnesses of a large number of objects. The field-of-view (the amount of sky you see) for these telescopes was comparatively small. The search soon started in earnest for a telescope which would allow astronomers to even more rapidly the sky. The Schmidt telescope design comprises a spherical mirror paired with an aspherical correcting lens. One of the most famous such telescopes, the 48-inch Palomar Schmidt telescope, covered the entire northern sky using thousands of 14-inch photographic plates and provided an invaluable discovery tool for astronomers.
In the 1970s, the advent of automated plate-scanning machines meant that the first digital surveys of the sky were in fact made with photographic plates by scanning all these plates! Similar southern sky surveys were made by the UK Schmidt telescope in Australia and such surveys were only surpassed by the arrival of true digital sky surveys like the SDSS. The SDSS, incidentally, bypasses the need for extremely wide-field optics by cleverly reading out the camera at exactly the rate of the earth’s rotation, but that’s another story.
However, a significant disadvantage with Schmidt telescopes is that the focal plane — where the image is recorded — is curved, making them impractical for use with flat electronic detectors unless heavy corrective optics are installed (yes, I grudgingly admit that photographic plates are not practical in a space observatory (although amazingly there were once spy satellites which used film).
In addition to this, don’t forget that also that one key requirement for Euclid is not simply to measure the positions, brightnesses and distances of all objects but also their shapes. For faint galaxies seen through ground-based telescopes, object shapes are dominated by atmospheric effects. For exposures longer than a few seconds, object light profiles are smeared out, severely limiting our ability to extract useful information.
For these reasons, Euclid is space: above the atmosphere, the telescope’s shape-measuring capabilities are limited only by the satellite’s optics and detectors. This is also why telescope designs which might have been fine for an instrument lying at the bottom of the murky soup of Earth’s atmosphere are simply not good enough for space. Essentially we need a design which preserves as much as information as possible concerning the intrinsic light profile of objects. And we also need to be able to calculate how much this light profile has been distorted by presence of telescope and detector optics – usually this is done by making observations of perfect point-like sources. In astronomy terms, stellar sources fit this bill very well. But what design is this?
Automated ray-tracing revolutionized telescope design in the second half of the 20th century. Without having to cut glass, computer programs could calculate the optical performances of a telescope even before it was built. In series of papers and described at length in a classic book, the optical engineer Detrich Korsch used these new techniques to perfect a compact, three mirror design which had the great advantage that it features a wide field of view, few optical surfaces, and almost no aberrations over the entire field of view. It’s worth mentioning that knowing the optical performance of Euclid requires an intimate knowledge of optical properties of all surfaces. For this reason, ground testing and qualification of all components are an important part of verifying the Euclid optical design.
But it’s not enough to have an excellent optical design if it is not stable and image quality cannot be maintained during normal operations. So, thermal expansion and contractions must be minimised. Euclid features a silicon carbide baseplate on which all the instruments and telescope are mounted. Silicon Carbide has the unique feature that it expands and contracts very little with changes in ambient temperature, meaning that the path length of the whole telescope can be rigidly controlled. The baseplate is actually created from a mould of particles of silicon carbide which are stuck together under pressure.
What’s the best place to put Euclid? At first, one might think, well, in orbit around the Earth, right? It turns out that a low-Earth orbit is a surprisingly hostile environment. In addition to constant sunrises and sunsets, there are also bands of nasty charged particles, in particular in the region called the South Atlantic anomaly. Hubble Space Telescope observatory is in such an low orbit, and the unfortunate consequence is that there are “blackout” periods which no observations cannot be made. In addition, there a not inconsiderable amount of background light.
There is a much better place to put a space observatory — the second Sun-Earth Lagrangian point, or L2, shown below. Here, a satellite’s location can be maintained with only a minimal expenditure of propellant. At L2, the gravitational pull of the Earth-Sun system almost perfectly balances inertial forces. Moreover, an object maintains an approximately constant distance to the Earth, making it ideal for high-bandwidth satellite communications: Euclid will need to send a lot of data to earth. In this orbit it will also be possible to control rigorously angle the sun’s rays fall on the telescope’s sunshield: this is essential to maintain the optical stability of the telescope. These factors have made L2 one of the best locations in the solar system to place an observatory, and many future telescopes will be placed there. The Planck and Herschel satellites clearly demonstrated all the benefits of this.
With this unique telescope design, capable of taking a high-resolution one-degree image of the sky with each exposure, Euclid’s primary mission will be completed in around six years of observations. No space satellite has ever flown before with such a unique set of instruments and telescope, and Euclid’s images of our Universe will be one of the most lasting legacies of the mission.
This article is one of a series of articles which will be appearing on the official blog of the Euclid Consortium before the end of the year!
Another trip: to Leiden and Noordwijk, the Netherlands. In Noordwijk, a seaside town, there is the headquarters of ESTEC, the European Space Research and Technology Centre. This is the European Space Agency’s technology centre.
In the excellent cafeteria, one can see things like this: | 0.835495 | 3.044598 |
A 'bucket full of photons' may yield clues about the Sun's magnetic fields
The first images from the National Science Foundation's 4-meter Inouye Solar Telescope, released in late January, revealed the Sun in jaw-dropping detail. The telescope's size—it is the largest solar telescope in the world—allowed researchers to zoom in on the solar surface at a higher resolution than ever before.
"You can use a big telescope, like the Inouye Solar Telescope, two ways," said Roberto Casini, a scientist at the National Center for Atmospheric Research (NCAR). "You can look at the Sun in the finest detail the telescope aperture allows, or you can sacrifice some of that detail to use the telescope like a photon bucket. The Inouye Solar Telescope gives us a very big bucket."
Scientists at NCAR's High Altitude Observatory (HAO) hope that using the telescope as a photon bucket will give them the opportunity to discover new signatures of polarization across the spectrum of visible light radiating from the Sun, which may have been too faint to find with previous smaller telescopes. Such signatures, which give scientists critical clues about the workings of the Sun's intricate magnetic fields, are easier to pick out when more sunlight can be captured.
To search for these signals, Casini and his HAO colleagues designed and built one of the Inouye Solar Telescope's five instruments: the Visible Spectro-Polarimeter (ViSP). This extremely versatile instrument can observe any wavelength across the visible spectrum of the Sun's radiation, allowing scientists a huge degree of flexibility to explore. It will also be coupled with a facility software package that will quickly turn the data collected by ViSP into a science-ready product. Casini hopes that ViSP's engineered flexibility and its data-processing capability will spark a renewed focus on what mysteries the Sun's polarized light can reveal.
NCAR is sponsored by the National Science Foundation (NSF). The Inouye Solar Telescope is managed by the NSF's National Solar Observatory.
From the few to the many: making spectro-polarimetery accessible
For more than a century, scientists have known that magnetic fields affect the light emitted or scattered by the ions in the solar atmosphere, producing polarization. By modeling and interpreting the polarization signature of these fields, scientists can trace the large-scale shape and structure of the Sun's magnetic fields. Ultimately, this will help researchers better understand solar eruptions and how to predict them. These violent events produce space weather that has the potential to disrupt radio communications, power grids, and GPS signals, as well as endanger astronauts and damage satellites.
But detecting and interpreting the polarized light from the Sun has always been a challenge. Part of the reason is because the signal is typically very weak, and scientists need to collect a lot of photons to distinguish that signal from the Sun's unpolarized background. The instruments used to detect polarization also contribute to this difficulty because they can introduce polarization themselves. For example, the mirrors used in telescopes to direct the path of the incoming light to the detector also polarize that light. The skill that has been needed to disentangle the polarized signal coming from the Sun and interpret that signal is quite specialized.
"Solar spectro-polarimetry up to this day has been an art mastered by only a few," Casini said.
HAO has a long history in the science of spectro-polarimetry and has built other instruments to study the Sun, including a spectro-polarimeter that is still operating at the Dunn Solar Telescope on Sacramento Peak in New Mexico. But the amount of observations taken by that instrument and others has far outstripped the amount of science-ready data made available to the community. This is because the observations are bottlenecked waiting for one of the few experts in the field to do the complex analysis needed to turn the raw data into something usable by a broad range of solar scientists.
Casini—who still keeps a cardboard box of tapes from Sacramento Peak sitting on his office floor until he has time to analyze them—says ViSP and the Inouye Solar Telescope are designed to break this bottleneck. The instrument, which can be set up and run with a minimum of human intervention, will feed data directly into facility software that can digest the information and transform it into a usable product for science.
"We want to overcome the inaccessibility of the science of polarimetry and create science-ready data for everybody," Casini said.
The possibility of discovering something new
The hands-off, automated design of ViSP has another distinct advantage as well. Unlike its predecessors, which have to be manually reconfigured to study different wavelengths of light, ViSP set up can be easily modified from a computer console to observe any wavelength in the Sun's visible spectrum.
With older, labor-intensive spectro-polarimeters, scientists have tended to stick with well-tested wavelengths of light that are already known to be sensitive to the Sun's magnetism. Scientists will be able to use ViSP to study these same wavelengths, and exploit the resolution of the Inouye Solar Telescope to look at this polarization in unprecedented detail.
But ViSP will also give scientists a license to explore the full spectrum of visible light, where they may stumble on new polarized signals that have never been discovered before and which could enrich their understanding of the Sun's magnetic fields. Finding these previously undiscovered signals is perhaps more likely with ViSP because, in addition to the instrument's automated flexibility, it is mounted beneath an enormous telescope capable of letting in so much light. New polarized signals may be fainter than those that are already known, and their detection will require an even larger pool of photons in order to isolate the signal from the noise.
"Because this is the largest solar telescope, it really provides an opportunity to look for new stuff—things that may have been neglected in the past because we didn't have enough light-collecting power," Casini said. "Now we have enough light."
ViSP is still in the final process of site acceptance and science verification, during which Casini and his colleagues are set to show that the instrument is meeting all the promised requirements and it is therefore scientifically viable. Once this process is complete the instrument will begin science operations. Ultimately, all the telescope's instruments, including ViSP, will be available for researchers across the world to use. Casini, for one, is excited for what solar researchers may learn.
"We have really produced an instrument that lets you explore the visible spectrum of the Sun however you want, and we may be surprised by what we find," he said. "There is a lot we still may learn from serendipitous discovery." | 0.812753 | 4.036695 |
In ancient times, people knew about the sun, the moon, the fixed stars, and exactly five “wandering stars” called planets. The movement of the planets was puzzling until Copernicus realized that the Earth too was a planet orbiting the sun just like the other five. But mankind’s knowledge the solar system exploded in the year 1610 thanks to a wonderful new invention: the telescope.
Hans Lippershey invented the telescope in the year 1608. He was a German-Dutch eyeglass maker, who found that a particular combination of lenses could make distant objects appear larger and closer than they do to the unaided eye. The following year, Galileo Galilei read about this remarkable instrument, and set about to build his own. By January 1610, Galileo had constructed one of the highest quality telescopes that existed at the time – though still very meager by modern standards. Galileo immediately set about exploring the night sky with his new creation and made several remarkable discoveries. He published a small book called “the Starry Messenger” in which he reported his findings and included instructions on how to build a telescope. Galileo found that the moon had mountains, valleys and craters. He found that there were vastly more stars in the Pleaides and in Orion’s belt and sword than could be detected by the unaided eye.
However, Galileo’s most remarkable discovery happened when he pointed his telescope at the planet Jupiter. He found that Jupiter had moons! No one had conceived of the possibility that other planets could have moons that orbit the planet, just as Earth’s moon orbits Earth. In fact, the idea was so novel, that Galileo did not even call them “moons” – a word that applied only to the moon at that time. Rather, these newly discovered moons looked like tiny bright stars in a telescope – stars that moved along with Jupiter. So Galileo referred to them as planets – wandering stars. But unlike the other five planets that orbit the sun directly, these four new planets orbit around Jupiter. Humanity had known of five planets (not including Earth) for five and a half millenia. And in one week, Galileo discovered four more. His excitement about this discovery is evident in his writings.
The Starry Messenger
In the introduction to the Starry Messenger, Galileo writes,
But what surpasses all wonders by far, and what particularly moves us to seek the attention of all astronomers and philosophers, is the discovery of four wandering stars not known or observed by any man before us. Like Venus and Mercury, which have their own periods about the sun, these have theirs about a certain star that is conspicuous among those already known, which they sometimes precede and sometimes follow, without ever departing from it beyond certain limits. All these facts were discovered and observed by me not many days ago with the aid of a spyglass which I devised, after first being illuminated by divine grace.
Note that he refers to the telescope as a “spyglass,” since the word ‘telescope’ had not yet been coined. Furthermore, Galileo concludes that these four new “planets” orbit Jupiter because they are sometimes ahead of Jupiter, and sometimes behind Jupiter in its motion through the heavens, as shown in the animation above. Jupiter’s rotation is not very tilted relative to its orbit around the sun, and hence we always see Jupiter nearly edge-on from our vantage point on Earth. Furthermore, the moons that Galileo discovered orbit in the plane of Jupiter’s equator, and so their orbits appear nearly edge-on. Consequently, they appear to go forward and backward as time progresses. Anyone with a small telescope can see Jupiter’s moons and will note that their positions relative to Jupiter change from night to night. Galileo’s discovery definitively proved that not everything in our solar system orbits Earth. This was a devastating blow to the geocentric (Earth-centered) solar system, and bolstered the heliocentric (sun-centered) model.
We now know that Jupiter actually has at least 79 moons! Most of them are very small – just a few miles across. But four are much larger – comparable in size to the Earth’s moon. These are the four discovered by Galileo. In honor of him, we refer to these as the Galilean satellites. They are very bright and can be seen in even a very modest telescope. In order of increasing distance from Jupiter, the moons are named Io, Europa, Ganymede, and Callisto. They are some of the most fascinating worlds of creation.
Orbital Properties of the Galilean Satellites
Io, the innermost of the Galilean Satellites, orbits Jupiter every 1.77 days at an average distance of 262,000 miles. That’s just a bit larger than the orbit of Earth’s moon, but the enormous gravity of Jupiter pulls Io around 15 times faster. Although the orbit is comparable in size to that of Earth’s moon, the planet Jupiter is much larger than Earth. So, in relative terms, Io orbits very close to its planet. Io orbits Jupiter at a distance of 6 Jupiter radii, whereas the moon orbits Earth at a distance of 60 Earth radii. Thanks to its short period, if you see Io on one side of Jupiter, the next evening you will likely see it on the other side of Jupiter.
The next moon out, Europa, orbits at a distance of 9.38 Jupiter radii with a period of 3.55 days. Notice that the period of Europa is twice that of Io. This is a 2:1 resonance. That is, when Io orbits Jupiter twice, Europa orbits Jupiter once. So, every two orbits of Io, it aligns with Europa. The next moon out, Ganymede, is also in resonance with both Io and Europa. Ganymede orbits at a distance of 15 Jupiter radii, with a period of 7.15 days – twice the period of Europa and four times that of Io. So, these three moons are in a 4:2:1 resonance.
Even more amazing is their configuration. Namely, whenever Io passes Europa, Ganymede is at a 90-degree angle relative to both of them. Whenever Europa passes Ganymede, Io is always on the opposite side of Jupiter, and the three moons form a straight line along with Jupiter. Whenever Io passes Ganymede, Europa is either on the opposite side, forming a straight line, or at a 60-degree angle. Apparently, this configuration has a stabilizing effect on these moons. In any case, no other known moons have such a unique orbital resonance.
Callisto, the outermost of the Galilean satellites, orbits at a distance of 26.3 Jupiter radii. Callisto has an orbital period of 16.7 days, and is not in resonance with the other three Galilean moons. All four Galilean moons are tidally locked. That is, like Earth’s moon, their rotational period matches their revolution period. Consequently, they keep the same face pointed at Jupiter at all times. This is true of all large moons, and many (but not all) small moons.
Since Jupiter has very little axial tilt relative to its orbit, and since the moons of Jupiter orbit around its equator, they often cast their shadow on Jupiter. These shadows are visible in a moderately-sized backyard telescope, appearing as a small black spot on Jupiter that slowly moves across its disk. You can use computer software or tables available on the internet to predict exactly when these events will occur. Jupiter will also cast its shadow on these moons when they are on the far side of the planet, rendering them invisible for an hour or so.
Every six years, the nodes of Jupiter’s equator align with the sun. For several months around this time, the Galilean satellites will occasionally cast their shadow on another Galilean satellite. This will cause the shadowed moon to fade rather dramatically and then brighten as the eclipse ends over the course of 15 to 30 minutes. Again, with modern technology these events are predictable to the second.
Physical Characteristics of the Galilean Satellites
Nine spacecraft have visited Jupiter. Of these, two (Galileo and Juno) went into orbit around Jupiter for an extended study. Thanks to these missions, we have detailed images and information on the Galilean satellites, as well as the other moons of Jupiter. To Galileo Galilei, these moons never appeared as anything more than bright stars. But we now know them as beautiful, diverse worlds, rich in detail.
Io is one of the most colorful, diverse, and unique moons in the entire solar system. Its strange rocky surface lacks the impact craters that are so common on all other solid worlds (except Earth). Instead, it has a yellow surface, with bits of orange/red and white, all due to various sulfur compounds. And Io is speckled with volcanoes. Unlike the dormant/extinct volcanoes on Mars, the volcanoes on Io are the most active in the entire solar system. When Voyager 1 flew past Jupiter, it detected nine erupting volcanic plumes on Io. Io is the most volcanically active world in the solar system. It has been completely resurfaced by volcanic activity since its creation.
Such extreme volcanic activity indicates that Io has significant internal heat. Since such heat cannot last billions of years, it may be evidence of the biblical timescale. Some heat can be generated in Io due to periodic tidal flexing caused when Io passes between Jupiter and Europa. Whether this generated heat is sufficient to last for the secular timescale is an open question.
With a diameter of 2270 miles, Io is just 5% larger than Earth’s moon, and 22% more massive. The nearly constant volcanic eruptions and evaporating sulfur frosts generate a thin atmosphere. This is very unusual: most moons have no atmosphere at all. Io has a weak magnetic field, possibly induced from the enormously powerful magnetic field of Jupiter. The interplay of these magnetic fields has created a torus of charged particles along Io’s orbit. This plasma torus is the subject of ongoing research.
With a diameter 10% smaller than Earth’s moon, Europa is the smallest of the four Galilean satellites. Its composition is mostly silicate rock, but with a surface of mostly water ice, which produces its near-white color. The darker regions on the trailing hemisphere are thought to have greater mineral content. Europa has an unusually smooth surface. Could it have been warm enough to be liquid when first created?
One of the most obvious and strange features of Europa are the large scratch marks along is surface. They are particularly prominent on the trailing hemisphere of this little moon. These are thought to be sites of cryogeyser activity – where the cracked surface has ejected plumes of water vapor due to internal heat. The Hubble Space Telescope has detected evidence of water plumes on Europa. Such internal heat is consistent with the biblical age of Europa – it has retained some of heat since creation. Tidal flexing may induce some internal heat, but Europa’s greater distance from Jupiter would make tidal forces weaker than they are for Io.
Next out is Ganymede. With a diameter of 3270 miles, it is the largest moon in the solar system. Ganymede is 51% larger than Earth’s moon, and is in fact 7% larger in diameter than the planet Mercury, though less than half as massive. Ganymede would undoubtedly be classified as a planet if it orbited the sun directly. But since Ganymede orbits Jupiter, it is a moon. Composed primarily of silicate rock and water-ice, Ganymede is the largest world without any substantial atmosphere. Due to its large size, Ganymede is often noticeably brighter than the other Galilean satellites as viewed through a telescope.
The surface appears tri-tone, with large dark brown regions resembling maria, interspersed with lighter brown regions, and speckled with white marks that appear to be ejecta from impacts. The lighter brown regions contain grooves and ridges, apparently the result of tectonic activity driven by internal heat. This is a problem for the secular timescale since such heat should have been exhausted long before the assumed secular age of these grooves. Ganymede’s orbit is too circular and too large for tidal flexing to produce any significant heat. Equally puzzling from a secular viewpoint is the existence of Ganymede’s magnetic field. This magnetic field is independent and not induced by the field of Jupiter. Yet, magnetic fields cannot persist for billions of years.
Callisto is the second-largest moon of Jupiter. It is 8% smaller than Ganymede in diameter, and 39% larger than Earth’s moon. It has a rocky/icy composition similar to the other Galilean satellites, but with lower density. Callisto lacks evidence of tectonic activity, and its surface is pockmarked with white craters.
The remaining 75 known moons of Jupiter are far smaller and fainter than the Galilean satellites, which is why they evaded detection until centuries later. The next moon of Jupiter to be discovered was Amalthea in the year 1892, followed by Himalia in 1904. These are each just over 100 miles in diameter. Yet, all the remaining 73 moons are much smaller, typically just a few miles across. Exact diameters are not meaningful for these moons because they are generally not round.
Most of the moons of Jupiter fall into six natural groups based on their orbital characteristics. We have already covered the Galilean family. But four small moons orbits even closer to Jupiter than the Galileans. These are Metis, Adrastea, Amalthea, and Thebe. This group forms the “inner” family. Like the Galileans, these moons are classified as “regular”, meaning their orbits have low eccentricity (they are nearly circular), low inclination (they orbit very nearly in the same plane as Jupiter’s equator), and are prograde (orbit in the same direction Jupiter rotates). This is a design feature; moons that orbit so close to Jupiter and to each other must have very organized motion. They avoid collision by revolving the same direction, in the same plane, and with nearly circular paths.
The remaining 71 moons orbit farther than Callisto and are irregular. Most fall into one of the four remaining families and each family is named after a prominent member of the group. The next group out beyond the Galilean group is the Himalia group, named after the largest moon in the group. The seven moons of the Himalia group orbit prograde – in the same direction Jupiter rotates. But they do not orbit in the plane of Jupiter’s equator. Instead, their orbits are inclined to the equator by anywhere from 27 degrees to 31 degrees. Their orbits are not as circular as the inner and Galilean groups, but are not tremendously eccentric either. The average eccentricity of the Himalia family is 0.16 (recall zero would be a perfect circle, and closed orbits must be less than 1.0).
Next out, we find the Ananke group, which consists of at least 20 moons. All these moons orbit retrograde (in the opposite direction in which Jupiter rotates). Their average eccentricity is around 0.23, so their orbits are a bit more eccentric than those of the Himalia group. All members of the Ananke group have an orbital inclination very close to 32 degrees. So there is considerable organization even at this distance from Jupiter.
Next out are the Carme and Pasiphae groups. Both groups have retrograde orbits, and they overlap each other in terms of their distance from Jupiter. The Carme group has 22 moons. Each moon has an orbital inclination very near 15 degrees. The average eccentricity for moons in this group is 0.27, and so we see how eccentricities increase with increasing distance from Jupiter. The Pasiphae group has at least 17 moons. They have an average orbital inclination of 32 degrees, just like the Ananke group, but with a much higher average eccentricity of 0.35 degrees.
Three irregular moons (Carpo, Themisto, and Valetudo) do not fall into any of these six families. Each of these three can be considered a family of one. All three are prograde with relatively high inclinations and eccentricities.
Patterns in Nature
The Jupiter system of moons is like a miniature solar system. The organization of the system is remarkable. The inner eight moons have low eccentricity, low inclination, and prograde orbits due to limited space. The outer moons can be either prograde or retrograde, and tend to have higher inclinations and eccentricities with increasing distance from the planet. This gives the outer moons a very disorganized look due to the apparent overlap of their orbits, but in fact we have seen that the orbits are organized into consistent groups. And since more space is available at extreme distances, there is greater diversity in orbital characteristics without any chance of collision. We will find that this is a common feature of the moons in our solar system, and of the solar system itself. We expect to find such patterns in nature because of the Lord who has imposed order on His creation.
|moon||avg distance (miles)||orbital period||diameter (miles)|
|Metis||79,500||7 hrs, 4.8 mins||25|
|Adrastea||80,200||7 hrs, 9.1 mins||10|
|Amalthea||112,700||11 hrs, 57.1 mins||129|
|Thebe||137,900||16 hrs, 12 mins||27|
|S/2003 J3||11,396,000||507 days||1|
|S/2010 J 2||12,618,000||591 days||1|
|S/2003 J 18||12,743,000||600 days||1|
|S/2017 J 7||12,817,000||605 days||1|
|S/2016 J 1||12,832,000||606 days||2|
|S/2017 J 3||12,859,000||608 days||1|
|S/2003 J 16||13,109,000||626 days||1|
|S/2017 J 9||13,351,000||643 days||1|
|S/2017 J6||13,953,000||687 days||1|
|S/2003 J 10||14,318,000||715 days||1|
|S/2011 J 2||14,369,000||718 days||1|
|S/2017 J 5||14,436,000||723 days||1|
|S/2017 J 8||14,436,000||723 days||1|
|S/2017 J 2||14,480,000||726 days||1|
|S/2003 J 9||14,531,000||731 days||1|
|S/2011 J 1||14,569,000||733 days||1|
|S/2010 J 1||14,571,000||734 days||1|
|S/2003 J19||14,623,000||737 days||1|
|S/2017 J 1||14,631,000||738 days||1|
|S/2003 J 23||14,644,000||739 days||1|
|S/2003 J 4||14,869,000||756 days||1|
|S/2003 J2||17,614,000||975 days||1|
The creation scientist Johannes Kepler in the 1610s was the first person to refer to Jupiter’s moons as “satellites” from the French word referring to an attendant or follower. Hence, any object orbiting a planet is a satellite. With the advent of modern space technology, we now have artificial satellites. And so, by contrast we refer to the moons of Jupiter as natural satellites, or more colloquially as moons.
Galileo was not claiming here to be the first person to make a telescope. He mentioned in this same publication that someone else had already discovered that putting two lenses in combination could make distant objects appear much closer. But Galileo had received no detailed instructions on how to do this. So he began experimenting with combinations of lenses on his own, until he discovered how to make a telescope and to compute the magnification. He shared these details in the Starry Messenger, hoping that others would also build a telescope and begin exploring the heavens leading to new discoveries.
There is one unconfirmed member of the Ananke group, which would make the count 21. Unconfirmed moons are included in the 79 count.
The inclination is often listed as 147 degrees due to their retrograde direction, and similarly for other retrograde moons.
As with the Ananke group, there is one unconfirmed member of the Pasiphae group, which would bring the number up to 18. | 0.867641 | 3.7142 |
Image:Â NASA/JPL/Space Science Institute
Planet Jupiter is one big (quite literally) mystery. From the powerful storm – the Red Spot- that somehow keeps going for centuries, and Jupiter’s famous stripes, that appear and disappear as they please, to the magnificent Jovian Auroras – scientists have trouble understanding what is going on with the king of planets. But perhaps the biggest puzzle of them all lies deep inside Jupiter – right in the core.
For decades we thought that Jupiter has three distinctive layers:
- an atmosphere of molecular hydrogen and helium
- an extensive mantle of metallic hydrogen and helium
- a dense compact core of ice, rock and metal.
This model fitted well with the widely accepted theory of Jupiter’s formation. The theory stated the planet started as a solid seed and later accumulated an extensive gaseous envelope.
But the data obtained by NASA Juno spacecraft suggest that Jupiter’s core is not what we were expecting! According to the observations, the solid material is not squashed into a compact ball in the planet’s center. Instead, the solid bits are mixed with the hydrogen in the mantle. The resulting nucleus is fuzzy, or, as astronomers say, diffuse, the core lacks a well-defined boundary and takes up to a half of the planet’s interior. How such a structure can possibly form, we don’t yet understand!Â
Fuzzy core as a result of Jupiter’s natural formation
One of the explanations to the fuzzy core phenomenon is that it was somehow formed naturally 4.5 billion years ago. Astronomers have been working very hard modeling processes that could have led to such a structure. So far they’ve been unsuccessful. For example, in the recent paper called The Challenge of Forming a Fuzzy Core in Jupiter the authors used a widely accepted core accretion* model to simulate Jupiter’s formation, while tweaking parameters to see if any combination could lead to the structure we observe today.
*Core accretion means that a core forms first and then accumulates lighter elements.
The authors concluded that “…none of our models leads to a structure of Jupiter today with an extended dilute core”.Â
Fuzzy core as a result of a giant impact
An alternative explanation (and in fact the first that popped into researchers minds) was collision. We know that collisions were common in the young Solar System. Many apparently strange things we observe today, like Uranus orbiting on its side and Venus spinning in the opposite direction to all other planets, can be explained by the dramatic planetary impacts early in the history of the Solar System.
Previously, we thought that baby Jupiter has avoided crashing into other protoplanets. But we might have been wrong. What if the fuzzy core that Juno spacecraft has discovered is a tell-tale of the past planetary smash? It is not impossible! In fact, the simulations show that a violent head-on collision with a massive planetary seed could have spread heavy elements over a large volume inside the gas giant. If a long time ago something indeed crashed into Jupiter, the impactor must have been really big, possibly 10 Earth masses or so – to destroy Jupiter’s own core, mix up the planet’s interior and form a structure we observe today. This “collision scenario” was first described in Nature in the article The formation of Jupiter’s diluted core by a giant impact.
But of course, there are other, less dramatic, possibilities. The erosion of the core might be responsible for the transfer of heavy elements to the outer layers. Or it might be something else entirely…
So what’s inside Jupiter and what made it that way? That’s one mind-bending mystery!Â
- Read Searching for life on Europa blog post to find out more about Jupiter’s moon EuropaÂ
- Read Rings around gas giants in the Solar System post to learn about structure and origin of the rings around Jupiter and other giant planets
As always, don’t hesitate to contact our wonderful portable planetarium team with your questions and comments! | 0.873495 | 3.931878 |
Throughout the Second World War, the town of Hillersleben, Germany was home to one of the Third Reich’s most crucial weapons research centers. At a sprawling facility nestled in the forested hills, a contingent of 150 engineers and physicists developed and evaluated all manner of experimental weapons, a substantial number of which were ultimately adopted by the Nazi war machine.
When Germany surrendered in May 1945, the scientists at Hillersleben were forced to abandon an assortment of death-bringing innovations at various stages of completion. Among these were a rocket-assisted artillery shell which had 50% more range than standard artillery, a 600mm mortar which fired one-ton self-propelled projectiles for up to three and a half miles, a modified Tiger tank which could fire 760-pound rockets up to six miles, and a chain-like projectile made up of small, linked rockets with a range of 100 miles. But the military masterminds’ most sinister ambitions were embodied in their behemoth Sonnengewehr, or “Sun Gun” project—an orbital weapon intended to exact fiery punishment upon the enemies of the Third Reich, forever establishing their dominance over the genetically inferior Untermenschen of the Earth.
The Sun Gun was based on a design originally conceived by Hermann Oberth, a physicist who is widely credited as one of the founding fathers of rocketry and astronautics. In his 1929 book Wege zur Raumschiffahrt, or “Ways to Spaceflight,” Oberth presented a scientific description of a hypothetical manned space station orbiting at an altitude of one thousand kilometers. He detailed potential construction methods using prefabricated sections, described a rotational cycle to produce centrifugal gravity within the station, and outlined a system for periodic resupply missions. Oberth advocated the development of these Raumstations to serve as astronomical observatories and telegraph relays, in addition to Earth-observing activities such as meteorology, search-and-rescue, and military intelligence. What interested the Nazi scientists, however, was his suggestion that a specially engineered 100-meter-wide concave mirror could be used to reflect sunlight into a concentrated point on the Earth. But whereas Oberth’s design had peaceful intentions—to use the intense heat to produce electricity with steam turbines—the nefarious Nazis envisioned a colossal heat ray which could vanquish humanity.
The Sun Gun concept was essentially a scaled-up version of Archimedes’ ancient and oft-debated “Death Ray.” In 212 BCE, the Roman Republic sought to seize the city of Syracuse from its Greek inhabitants. Some accounts claim that the initial attack was repelled by Archimedes—the astonishingly talented Greek mathematician, physicist, inventor, and astronomer—who is said to have used an array of sunlight-concentrating copper mirrors to set the advancing ships aflame. Many scientific attempts have been made to confirm or deny the feasibility of such a weapon, with varying outcomes. Most prominently, the myth was “busted” on the television program MythBusters in 2006. The ‘Busters found that an array of metal mirrors could indeed ignite a wooden ship, but only after a tactically-tricky exposure of several minutes. Although the authenticity of the ancient legend is questionable, however, the principle behind it is fundamentally sound.
Using Hermann Oberth’s 1929 design as a starting point, the optimistic physicists of Hillersleben expanded upon the space-mirror concept considerably. Their calculations indicated a parabolic mirror of at least three square kilometers to achieve the desired destructive power—about 100,000 times larger than Archimedes’ mythical death ray—and an ideal orbit of 8,200 kilometers. After considering a number of shiny materials, the scientists settled upon metallic sodium, an element which is relatively abundant among natural compounds. Under ordinary conditions, pure sodium tarnishes quickly and reacts violently to moisture, however the researchers reasoned that these shortcomings would not pose any problem in the virtually vacuous exosphere. To heft the pre-built pieces into orbit, engineers planned to employ a beefed-up version of trailblazing-but-treacherous V-2 rocket which Germany had been using to terrorize London. This “A11” multi-stage variant—which was undergoing development at the V-2 facility in Peenemünde—was designed by Wernher von Braun to deliver people into space, and to export white-hot Nazi shrapnel to the US.
Inside the living area of the station, electricity would be provided by special steam-driven dynamos which would utilize the heat of raw solar radiation. The station’s complement of Nazi astronauts would wear magnetic shoes to accommodate working in weightlessness, and their oxygen would be constantly replenished by vast onboard greenhouses filled with CO2-thirsty pumpkin plants.
The crew of a fully-assembled Sun Gun station would receive encoded orders via radio or wireless telegraph, while keeping a sharp eye on enemies of the Reich. When commanded to attack a terrestrial target, the crew would engage a network of rocket thrusters to rotate the massive reflector into a carefully calculated orientation. Once in position, the mirror’s curvature would converge the sun’s mighty rays into a focal point on the Earth’s surface, pouring a column of raw, super-concentrated solar radiation upon the target site. Hypothetically this beam would have sufficient heat to scorch away fields, incinerate cities, vaporize reservoirs, and melt screaming onlookers like wax dummies. Any nation lacking space-capable rockets would be utterly defenseless against the onslaught. Once the desired destruction threshold was reached, the mirror would be tilted back into a safe orientation, facing away from the Earth.
The project was stalled in the
summer spring of ’45, however, as the impending Allied victory became increasingly evident. American intelligence agencies immediately invoked Operations Overcast and Paperclip to extricate German scientists and equipment ahead of the Soviets. Lieut. Col. John A. Keck, chief of the Ordinance Service’s enemy technical intelligence branch in European theater, led the interrogation of a number of Nazi researchers. The German engineers described their participation in the development of the V-2, and disclosed details regarding several other nearly-perfected technologies: a submarine-based V-2 launch system, an infrared sniper scope, and an anti-aircraft rocket capable of auto-detonating within ten yards of a target. In addition, they handed over the schematics and calculations for their formidable Sun Gun concept. Considering the Nazi scientists’ other impressive achievements, Lieut. Col. Keck and his team of hard-headed engineers took the death star concept seriously. “We were impressed with their practical engineering minds,” Keck said of the Hillersleben researchers, “and their distaste for the fantastic.”
Many American scientists, however, were more skeptical Sun Gun’s feasibility. Astronomical amounts of time, money, and resources would be required to hoist the hundreds of tons of equipment into orbit, not to mention the million or so tons of metallic sodium. Furthermore, there were doubts regarding whether a single parabolic mirror could concentrate destructive levels of energy upon such a distant focal point; though this problem could be overcome by building multiple Sun Guns to operate as an orchestrated orgy of annihilation. In spite of the monumental scale of the concept, the physicists from Hillersleben were confident that their Sonnengewehr Raumstation was feasible, and that its uninterrupted development could have furnished the Fatherland with global conquest in as little as fifty years.
The weaponization of the sun has still yet to be realized, though similar concepts are used today to collect heat on smaller scales. Solar furnaces use parabolic mirrors provide heat for cooking, electricity, metal-working, and hydrogen production. The largest solar furnace in the world is currently located in the commune of Odeillo in the French Pyrenees mountains, where its eight-story-tall array of 10,000 small mirrors concentrates sunlight to produce temperatures up to 3,000 degrees Celsius. A similar concept is used in solar power towers, where a brigade of mirrors reflect the sun’s heat onto a central receiver to produce steam for electricity.
Despite appearances, the Hillersleben researchers were not exclusively sinister. Nestled amongst the heat-ray-of-doom diagrams, scientists included notes describing the space station’s potential as a radio-relay satellite, a weather observation post, a launch pad for the interstellar rocket expeditions, and of course, Hermann Oberth’s original vision to use the giant mirror to generate electricity on Earth.
Many German rocket scientists—including Oberth and Wernher von Braun—ultimately opted to put science ahead of patriotism, and moved to the US to continue their rocketry research. In addition to their work with US missile defense systems, many of the men went to work for the fledgling space program in the 1950s. The rocket originally slated to carry the Sun Gun segments into space—Von Braun’s A11—eventually became the foundation for the Saturn V, the engine which carried the Apollo astronauts into orbit for the moon missions of 1969-1972. It seems that through hard work and perseverance, these pioneers of rocketry finally managed to hit their ultimate goal: The stars. And occasionally, London. | 0.845435 | 3.088274 |
If a person goes outside on a clear, moonless night in the countryside, far from city lights, he or she will be treated to a breathtaking sight. Above stretches a velvet black canopy studded with thousands of pinpoints of light, some bright and lustrous, others so faint they are barely visible. Most of these, of course, are stars like the Sun, except that they lie much farther away than the huge gaseous ball whose light and heat make life on Earth possible.
A few of the brighter points of light in the dark canopy are planets in our own solar system, the Sun's family. But these few easily visible solid bodies, each thousands of miles in diameter, are only the tip of the iceberg, so to speak, of the material making up the solar system. Lurking in the darkness among them, usually invisible to unaided human eyes, are billions of smaller objects. Some are no larger than cars or houses, while others are five, ten, fifty, or a hundred miles across. "Lost amid the stars," writes noted science historian Curtis Peebles, "there are mountains in the sky. Some are worlds in their own right, others are the irregular splinters of collisions [that happened] ages ago." 1
Those orbiting mountains that are composed mainly of metal and rock are known as asteroids, while those made up mostly of ice and rock are comets. Because of their relatively small size (as compared to planets and stars), most asteroids and comets are difficult to see without the use of a large telescope; however, on occasion a comet will grow a tail and pass near enough to Earth to become visible to the naked eye.
For these reasons, no one knew about the existence of asteroids until modern times, when large telescopes became common. In contrast, people have seen comets since ancient times, indeed since modern humans first appeared on Earth more than a hundred thousand years ago. Over the centuries,various peoples assigned names to these objects, and because comets have such a distinct look–like fuzzystars with cloud like tails–most of the names are similar to one another. The ancient Chinese called them "broom stars," for example. The Aztecs, who dwelled in what is now Mexico, called them "smoking
Whatever the ancients chose to call comets, nearly all agreed that these objects were omens, or supernatural signs, of one kind or another. The most common view was that they foretold coming disasters or ill fortune. An ancient Chinese document titled Record of the World's Change states:
Comets are vile stars. Every time they appear in the south, something happens to wipe out the old and establish the new. Also, when comets appear, whales die. In Sung . . . times, when a comet appeared in the constellation of the Big Dipper, all soldiers died in chaos. . . . When a comet appears in the North Star, the emperor is replaced. If it appears in the end of the Big Dipper, everywhere there are uprisings and war continues for several years. If it appears in the bowl of the Dipper, a prince controls the emperor. Gold and gems become worthless. . . . Scoundrels harm nobles. Some leaders appear, causing disturbances. Ministers conspire to rebel against the emperor. 2
The other common belief regarding cometary omens was that they signaled the birth, death, or military victories of great kings, generals, and other human leaders. The immortal English playwright William Shakespeare summarized it best in a famous line from his play Julius Caesar: "When beggars die, there are no comets seen; the heavens themselves blaze forth the death of princes." 3 In fact, the passing of the real Julius Caesar, some sixteen centuries before Shakespeare wrote these lines, was said to have been marked by a comet. According to Caesar's Greek biographer Plutarch: "Of [the] supernatural events [marking Caesar's death] there was, first, the great comet which shone very brightly for seven nights after Caesar's murder and then disappeared." 4 Similarly, in Plutarch's own time, a comet that became visible in A . D . 79 was widely believed to be associated with the death of the Roman emperor Vespasian. (The idea that comets were harbingers of disaster was still commonplace; in A . D . 66, a bright comet was seen as an omen of the destruction of the city of Jerusalem that year by the Romans.)
Not all of the ancients were convinced that comets were completely supernatural, however. The Greek philosopher-scientist Democritus (born in 460 B . C .) was the first known person to suggest that these celestial objects might have natural origins. He proposed that comets existed among the distant stars and planets and formed when one of these bodies came too near another. In the following century, the more influential Greek thinker Aristotle disagreed. In his view, comets were natural, but they existed inside Earth's own atmosphere—the result of hot, dry gases seeping out of the ground and igniting high in the air.
A few centuries later, the Roman playwright and thinker Seneca the Younger declared that Aristotle was wrong. In a treatise titled On Comets , the seventh book of a larger work, the Natural Questions , Seneca argued that comets could not be moving through the atmosphere. If they were, he said, the wind should disturb their movements, yet even after a sudden storm a comet stayed on its stately path. Seneca was not exactly sure what comets were. But he had the humility to admit it and the foresight to predict that future scientists would discover the truth. "The day will come," he wrote,
when the progress of research through long ages will reveal to sight the mysteries of nature that are now concealed. A single lifetime, though it were wholly devoted to the study of the sky, does notsuffice for the investigation of problems of such complexity. . . . It must, therefore, require long successive ages to unfold all. The day will yet come when posterity [future generations] will be amazed that we remained ignorant of things that will to them seem so plain. . . . The man will come one day who will explain in what regions the comets move, why they diverge so much from the other stars, what is their size and their nature. Many discoveries are reserved for the ages still to be when our memory shall have perished. . . . Nature does not reveal all her secrets at once. 5
Seneca's voice of reason regarding comets and other aspects of the heavens had little or no effect on the thinking of later generations. In medieval times, the ancient superstitions about comets continued to prevail. In the seventh century, Isidor, Bishop of Seville, an influential Christian historian, declared that comets foreshadow wars and disease epidemics. And the fact that from time to time comets did materialize during wars was enough to convince most people that the bishop must be right.
In 1066, for instance, a bright comet appeared just as William the Conqueror was invading England. The common belief at the time was that this apparition was an evil omen for England's King Harold, and indeed, Harold soon went down to defeat, initiating the Norman occupation of the country. (The well-known Bayeux Tapestry, celebrating the Norman victory, shows the comet, which modern scientists now agree is the famous Halley's comet in one of its many periodic visits to Earth's neighborhood.)
Incredibly, a certain degree of fear and awe of comets continued into modern times, even after science showed conclusively that these objects are simply stray chunks of ice and rock roaming the solar system. When Comet Biela passed close to Earth in 1892, for example, terror gripped many people across the globe. Typical of the reactions were those reported in an Atlanta, Georgia, newspaper:
The fear which took possession of many citizens has not yet abated. The general expectation hereabouts was that the comet would be heard from on Saturday night. As one result, the confessionals of the two Catholic churches here were crowded yesterday evening. As the night advanced, there were many who insisted that they could detect changes in the atmosphere. The air, they said, was stifling. . . . Tonight (Saturday) they [the churches] are all full, and sermons suited to the terrible occasion are being delivered. 6
Today, by contrast, astronomers and other scientists view comets and their cosmic cousins, asteroids, as more fascinating than frightening and find that much can be learned from studying them. Both of these classes of celestial bodies have been around for billions of years. So they offer important clues to conditions in the solar system during its early years.
In addition, comets and the materials composing them may well have crucial connections to human beings and other life on Earth. "Comets are the least understood objects in the solar system," says NASA comet expert Donald Yeomans. "And they're probably the most important when it comes to you and me." 7 Yeomans is referring to the current theory that much of the water on Earth was delivered by in-falling comets, as well as another hypothesis that organic compounds in comets brought the precursors of life to our planet.
The very fact that comets, and asteroids too, do occasionally fall to Earth is another reason that these bodies are important to humans. Nearly all scientists now accept that the impact of a comet or asteroid wiped out more than half the animal species on the planet, including the dinosaurs, 65 million years ago. Such disasters can and will happen again in the future. Ironically, therefore, ancient fears of these objects were not totally misplaced, even if the reasons given in those days were wrong. What is certain is that the more we study and understand these bodies, the better chance we have of controlling them and keeping them from wiping out human civilization. After all, it is and always will remain in the best interest of everyone for the millions of mountains that hurtle through the sky to stay in their own domain. | 0.864273 | 3.729968 |
The James Webb Space Telescope, described in my last column, is nearing completion and expected to be sent into space by 2021. It will replace the aging Hubble Space Telescope, which has made incredible scientific discoveries over the past three decades.
Science questions that the JWST could answer include: What did the first galaxies look like? Do those galaxies cluster in the way predicted from theoretical models of the Big Bang, including dark matter and dark energy? The Nobel Prize in Physics was awarded this year partially to James Peebles, who pioneered theoretical calculations of the early universe. Clearly, these are important questions that the JWST can answer.
The JWST will take pictures using infrared light, whereas HST’s primary camera uses optical light. Because the universe is expanding, optical light from the early universe gets shifted to the infrared. The JWST will be able to look back further in time, to see galaxies as they were first forming.
The HST also has an infrared camera, but the JWST will provide a major step up in both sensitivity and resolution. For example, the JWST mirror is 15 times larger in area than the HST mirror. Unlike Hubble, the JWST will be shielded to block the sun’s infrared light, giving clearer pictures. Just like with HST’s breathtaking optical pictures, astronomers expect to make new discoveries once JWST is operational.
What might the JWST discover? Keeping an open mind, it might find that galaxies cluster in a way different from that predicted by the Big Bang. That would cause cosmologists to rethink the current theory of the early universe. On the other hand, if the first galaxies cluster in the way predicted, it would confirm our current picture of the Big Bang and perhaps give clues about the origin of dark matter.
Another science question that JWST could answer is about the formation of supermassive black holes. Today, astronomers believe there is a supermassive black hole at the center of each galaxy. The one at the center of our Milky Way is 4 million times the mass of our sun. An even bigger one — about 100 million times the sun’s mass — is at the center of Andromeda, our nearest neighboring galaxy. It is an open question of how such massive beasts came to be.
Whether the JWST confirms or disproves the current theory of the early universe, it will be another step forward for science. It’s an example of how the scientific method works: gather facts, make a theory that fits the facts, then set out to predict and measure new data.
Kenneth Hicks is a professor of physics and astronomy at Ohio University in Athens. | 0.822402 | 4.030832 |
Traveling the solar system could one day be as easy as taking a bus to work. Scientists envision self-driving spaceships ferrying astronauts through deep space, and GPS-like systems guiding visitors across the terrains of other planets and moons. But for those futuristic navigation schemes, spacecraft and satellites would need to be equipped with clocks that keep time with extreme precision — more precise than any timepiece ever sent to space.
A prototype of that clock is scheduled to launch on June 24 for a test flight.
NASA’s Deep Space Atomic Clock, or DSAC for short, counts off the seconds with ticks that are about 50 times more uniform than those of atomic clocks onboard GPS satellites. That’s on par with the ground-based atomic clocks used for the agency’s Deep Space Network — the cadre of earthbound facilities that use radio antennas to communicate with missions throughout the solar system. But unlike those refrigerator-sized timepieces, the toaster-sized DSAC is small enough to carry aboard a spacecraft.
Outfitted on future spaceships or satellites, this mini atomic clock could “completely change the way we navigate spacecraft through deep space,” Jill Seubert, deputy principal investigator for the project, said June 10 in a news conference.
After the prototype launches from NASA’s Kennedy Space Center at Cape Canaveral, Fla., researchers will monitor its performance in low-Earth orbit for one year. Here’s a preview of what the clock could mean for future spacefaring.
How would the clock change space navigation?
“Every single spacecraft exploring deep space today relies on navigation that’s performed back here at Earth,” said Seubert, who’s based at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. Earth-based antennas send signals to spacecraft, which the spacecraft echo back. By measuring a signal’s round-trip time within a billionth of a second, ground-based atomic clocks in the Deep Space Network help pinpoint the spacecraft’s location.
With the new Deep Space Atomic Clock, “we can transition to what we call one-way tracking,” Seubert said. A spaceship would use such a clock onboard to measure the time it takes for a tracking signal to arrive from Earth, without having to send that signal back for measurement with ground-based atomic clocks. That would allow a spacecraft to judge its own trajectory.
What are the perks of one-way tracking?
Having a spacecraft that’s able to track its location would allow astronauts to steer themselves through the solar system without needing instructions from Earth. “At a place like Mars, the round trip [tracking signal] time can range something like eight to 40 minutes,” says the project’s principal investigator Todd Ely, also based at NASA’s Jet Propulsion Lab. “At Jupiter, it can be … an hour and a half. Saturn, two and a half hours.”
With a craft enabled to track itself, explorers could execute more nimble maneuvers and react more quickly to unexpected situations. “Far term, I’m really excited about … using the clock with other navigation instruments onboard to create something like a self-driving spacecraft,” Ely says.
How would the clock enable navigation on other worlds?
“Just imagine an astronaut hiking on Mars, and maybe Olympus Mons is rising in the background, and she’s checking her Google Maps Mars Edition to see where she is,” Seubert said at the news conference. “The concept would really be the same as what we have for GPS here” on Earth, with a constellation of satellites providing global coverage to the surface.
On other worlds, satellites would use onboard Deep Space Atomic Clocks to broadcast signals with precise timestamps, which could be used by any GPS ground receiver to triangulate its position.
What makes the new space clock more reliable than others?
The new atomic clock keeps time using charged mercury atoms, or ions, whereas clocks currently aboard Earth’s GPS satellites use neutral rubidium atoms. Since the mercury atoms in the new clock have electric charge, they can be trapped in electric fields that prevent them from interacting with the walls of their container — interactions that in GPS atomic clocks cause the rubidium atoms to fall out of rhythm, Ely explains.
Earth’s GPS satellite clocks require twice-daily corrections from a command center on Earth. But the new atomic clock is far more reliable in ticking uniformly, so corrections wouldn’t be needed so frequently. “If you had the Deep Space Atomic Clock,” Ely says, “twice a day could turn into weeks, if not months.”
What will scientists test during the prototype’s first flight?
Scientists need to ensure that the steadiness of the clock’s ticking holds up in space. “Our goal is a [gain or loss of time] of about two nanoseconds or less per day,” Ely says. “We think we’re going to get close to about three-tenths of a nanosecond per day.”
This dress rehearsal spaceflight will also test how the clock fares for an entire year in space. “This will tell us a lot about how we can operate these clocks for much longer time periods when they’re traveling to places that might take months or years or even a decade to get to,” Seubert said. Researchers expect to share preliminary results on how well the clock is keeping time in space later this year. | 0.815876 | 3.351022 |
Black holes are objects of the universe that attract the interest of many astronomers. Black holes, space objects, the existence of which is predicted by the general theory of relativity. They are formed during unlimited gravitational collapse of massive cosmic bodies (in particular, stars with masses of 40-60 M?). Gravity collapse – catastrophically fast compression of a star under the influence of gravitational forces (gravity).
The external structure of the black hole
A black hole has an external gravitational field, the properties of which are determined by mass, angular momentum and, possibly, electric charge if the collapsing star was electrically charged. At large distances, the black hole field practically does not differ from the gravitational fields of ordinary stars, and the motion of other bodies interacting with the black Continue reading
In the 1840s, with the help of Newtonian mechanics, Urbain Le Verrier predicted the position of the then undetected planet Neptune based on an analysis of perturbations of the orbit of Uranus. Subsequent observations of Neptune at the end of the 19th century led astronomers to suggest that, in addition to Neptune, another planet also has an impact on the orbit of Uranus. In 1906, Percival Lowell, a wealthy resident of Boston who founded the Lowell Observatory in 1894, initiated an extensive project to find the ninth planet in the solar system, which he named Planet X. By 1909, Lowell and William Henry Pickering had suggested several possible celestial coordinates for this planet. Lowell and his observatory continued to search for the planet until his death in 1916, but to no avail. In fact, on March 19, 1915, two low-level images of Pluto were obtained at his observatory without Lowell’s knowledge, but he was not recognized on them.
Mount Wilson Observatory could also claim the discovery of Pluto in 1919. That year, Milton Humason, on behalf of William Pickering, searched for the ninth planet, and Pluto’s image fell on a photographic Continue reading
We have already seen that all attempts by cosmologists to squeeze the Universe into the narrow framework of their materialistic ideas have led to nothing. Moreover, their theories do not even correspond to their own ideas about the structure of the Universe. For example, the big bang theory cannot explain the existence of galaxies. Imagine a brilliant scientist who thoroughly knows all modern cosmological theories, but does not have a clue about astronomy. Can he predict the existence of galaxies? Not. Modern versions of cosmological theories predict only the appearance of a uniform cloud of gas. The density of this cloud by now should be no more than one atom per cubic meter – a little better than vacuum. To get something more, you need to adjust the initial state of the Universe, which is very difficult to Continue reading | 0.893674 | 3.90491 |
Rise early for a total lunar eclipse on the 21st
Any month that has the glorious constellation of Orion in our southern evening sky is a good one for night sky aficionados. Add one of the best meteor showers of the year, a total eclipse of the Moon, a meeting between the two brightest planets and a brace of space exploration firsts and we should have a month to remember
Orion rises in the east as darkness falls and climbs well into view in the south-east by our star map times. Its two leading stars are the blue-white supergiant Rigel at Orion’s knee and the contrasting red supergiant Betelgeuse at his opposite shoulder – both are much more massive and larger than our Sun and around 100,000 times more luminous.
Below the middle of the three stars of Orion’s Belt hangs his Sword where the famous and fuzzy Orion Nebula may be spied by the naked eye on a good night and is usually easy to see through binoculars. One of the most-studied objects in the entire sky, it lies 1,350 light years away and consists of a glowing region of gas and dust in which new stars and planets are coalescing under gravity.
The Belt slant up towards Taurus with the bright orange giant Aldebaran and the Pleiades cluster as the latter stands 58° high on Edinburgh’s meridian. Carry the line of the Belt downwards to Orion’s main dog, Canis Major, with Sirius, the brightest star in the night sky. His other dog, Canis Minor, lies to the east of Orion and is led by Procyon which forms an almost-equilateral triangle with Sirius and Betelgeuse – our so-called Winter Triangle.
The Moon stands about 15° above Procyon when it is eclipsed during the morning hours of the 21st. The event begins at 02:36 when the Moon lies high in our south-western sky, to the left of Castor and Pollux in Gemini, and its left edge starts to enter the lighter outer shadow of the Earth, the penumbra.
Little darkening may be noticeable until a few minutes before it encounters the darker umbra at 03:34. Between 04:41 and 05:46 the Moon is in total eclipse within the northern half of the umbra and may glow with a reddish hue as it is lit by sunlight refracting through the Earth’s atmosphere. The Moon finally leaves the umbra at 06:51 and the penumbra at 07:48, by which time the Moon is only 5° high above our west-north-western horizon in the morning twilight.
This eclipse occurs with the Moon near its perigee or closest point to the Earth so it appears slightly larger in the sky than usual and may be dubbed a supermoon. Because the Moon becomes reddish during totality, there is a recent fad for calling it a Blood Moon, a term which has even less of an astronomical pedigree than supermoon. Combine the two to get the frankly ridiculous description of this as a Super Blood Moon.
Sunrise/sunset times for Edinburgh change from 08:44/15:49 on the 1st to 08:10/16:43 on the 31st. New moon early on the 6th, UK time, brings a partial solar eclipse for areas around the northern Pacific. First quarter on the 14th is followed by full moon and the lunar eclipse on the 21st and last quarter on the 27th.
The Quadrantids meteor shower is active until the 12th but is expected to peak sharply at about 03:00 on the 4th. Its meteors, the brighter ones leaving trains in their wake, diverge from a radiant point that lies low in the north during the evening but follows the Plough high into our eastern sky before dawn. With no moonlight to hinder observations this year, as many as 80 or more meteors per hour might be counted under ideal conditions.
Mars continues as our only bright evening planet though it fades from magnitude 0.5 to 0.9 as it recedes. Tracking through Pisces and well up in the south at nightfall, it stands above the Moon on the 12th. Our maps show it sinking in the south-west and it sets in the west before midnight.
Venus, its brilliance dimming only slightly from magnitude -4.5 to -4.3, stands furthest west of the Sun (47°) on the 6th and is low down (and getting lower) in our south-eastern predawn sky. Look for it below and left of the waning Moon on the 1st with the second-brightest planet, Jupiter at magnitude -1.8, 18° below and to Venus’s left. As Venus tracks east-south-eastwards against the stars, it sweeps 2.4° north of Jupiter in an impressive conjunction on the morning of the 22nd while the 31st finds it 8° left of Jupiter with the earthlit Moon directly between them.
Saturn, magnitude 0.6, might be glimpsed at the month’s end when it rises in the south-east 70 minutes before sunrise but Mercury is lost from sight is it heads towards superior conjunction on the Sun’s far side on the 30th.
China hopes that its Chang’e 4 spacecraft will be the first to touch down on the Moon’s far side, possibly on the 3rd. Launched on December 7 and named for the Chinese goddess of the Moon, it needs a relay satellite positioned beyond the Moon to communicate with Earth.
Meantime, NASA’s New Horizons mission is due to fly within 3,500 km of a small object a record 6.5 billion km away when our New Year is barely six hours old. Little is known about its target, dubbed Ultima Thule, other than that it is around 30 km wide and takes almost 300 years to orbit the Sun in the Kuiper Belt of icy worlds in the distant reaches of our Solar System.
Diary for 2019 January
1st 06h New Horizons flyby of Ultima Thule
1st 22h Moon 1.3° N of Venus
2nd 06h Saturn in conjunction with Sun
3rd 05h Earth closest to Sun (147,100,000 km)
3rd 08h Moon 3° N of Jupiter
4th 03h Peak of Quadrantids meteor shower
6th 01h New moon and partial solar eclipse
6th 05h Venus furthest W of Sun (47°)
12th 20h Moon 5° S of Mars
14th 07h First quarter
17th 19h Moon 1.6° N of Aldebaran
21st 05h Full moon and total lunar eclipse
21st 16h Moon 0.3° S of Praesepe
22nd 06h Venus 2.4° N of Jupiter
23rd 02h Moon 2.5° N of Regulus
27th 21h Last quarter
30th 03h Mercury in superior conjunction
31st 00h Moon 2.8° N of Jupiter
31st 18h Moon 0.1° N of Venus
This is a slightly revised version, with added diary, of Alan’s article published in The Scotsman on December 31st 2018, with thanks to the newspaper for permission to republish here.
Geminids suffer in the supermoonlight
The Sun reaches its farthest south at our winter solstice at 10:44 GMT on the 21st, as Mars and the brilliant Venus stand higher in our evening sky than at any other time this year. This is not a coincidence, for both planets are tracking eastwards and, more importantly, northwards in the sky as they keep close to the ecliptic, the Sun’s path over the coming weeks and months. Meantime, Jupiter is prominent during the pre-dawn hours while Orion is unmistakable for most of the night and strides proudly across the meridian at midnight in mid-December.
As the sky darkens this evening, Pegasus with its iconic, but rather empty, Square is nearing the meridian and the Summer Triangle (Vega, Deneb and Altair) stands high in the south-west.
By our map times, Altair is setting in the west and Orion stands in the south-east, the three stars of Belt pointing down to where Sirius, our brightest night-time star, will soon rise. Sirius, the red supergiant Betelgeuse at Orion’s shoulder and Procyon in Canis Minor, almost due east of Betelgeuse, form a near-equilateral triangle which has come to be known as the Winter Triangle.
Above Orion is Taurus, home to the Pleiades star cluster and the bright orange giant star Aldebaran, the latter located less than halfway between us and the V-shaped Hyades cluster.
Look for the almost-full Moon below the Pleiades and to the right of Aldebaran and the Hyades on the evening of the 12th and watch it barrel through the cluster during the night, occulting (hiding) several of the cluster’s stars on the way. As they dip low into the west on the following morning, the Moon occults Aldebaran itself, the star slipping behind the Moon’s northern edge between 05:26 and 05:41 as seen from Edinburgh. Even though this is the brightest star to be occulted this year, the Moon’s brilliance means we may well need a telescope to view the event.
Sunrise/sunset times for Edinburgh vary from 08:20/15:44 on the 1st to 08:42/15:40 on the 21st and 08:44/15:48 on the 31st. The Moon is at first quarter on the 7th and full on the 14th when, once again, it is near its perigee, its closest point to the Earth. Despite the fact that the Moon appears a barely perceptible 7% wider than it does on average, we can look forward to yet another dose of over-hyped supermoon hysteria in the media. The Moon’s last quarter comes on the 21st and it is new on the 29th.
Sadly, the Moon does its best to swamp the annual Geminids meteor shower which lasts from the 8th to the 17th and is expected to peak at about 20:00 on the 13th. Its meteors are medium-slow and, thankfully, there are enough bright ones that several should be noticeable despite the moonlight. Without the moonlight, and under perfect conditions, this might have been our best display of 2016, with 100 or more meteors per hour.
Geminids are visible in all parts of the sky, but perspective makes them appear to diverge from a radiant point near the star Castor in Gemini, marked near the eastern edge of our north map. This radiant climbs from our north-eastern horizon at nightfall to pass high in the south at 02:00.
Venus stands 10° above Edinburgh’s southern horizon at sunset on the 1st and shines spectacularly at magnitude -4.2 as it sinks to set in the south-west almost three hours later. The young earthlit Moon stands 10° above-right of Venus on the 2nd, 5° above the planet on the 3rd and, one lunation later, 20° below-right of the Moon on Hogmanay. By then, Venus is twice as high at sunset and (just) brighter still at magnitude -4.3. A telescope shows its dazzling gibbous disk which swells from 17 to 22 arcseconds in diameter as the sunlit portion shrinks from 68% to 57%.
As Venus speeds from Sagittarius to Capricornus, so Mars keeps above and to its left as it moves from Capricornus into Aquarius and into the region of sky above our south-western horizon at the map times. Mars is only a fraction as bright, though, and fades from magnitude 0.6 to 0.9. It also appears much smaller, only 6 arcseconds, so that telescopes now struggle to reveal any surface features. Spot Mars to the left of the Moon on the 4th and below-right of the Moon on the 5th.
Mercury is farthest east of the Sun, 21°, on the 11th but hugs our south-western horizon at nightfall and is unlikely to be seen. It reaches inferior conjunction between the Sun and Earth on the 28th by which time Saturn, which passes beyond the Sun on the 10th, might just be glimpsed low above the south-eastern horizon before dawn. On the 27th, it shines at magnitude 0.5 and lies 7° below-left of the slender waning Moon.
Jupiter is conspicuous at magnitude -1.8 to -1.9 and the real star of our morning sky. Rising in the east for Edinburgh at 03:04 on the 1st and 01:31 on the 31st, it climbs well up into our southern sky before dawn where it stands above Virgo’s leading star Spica and draws closer during the month.
Jupiter, Spica and the Moon form a neat triangle before dawn on the 23rd, when Jupiter is 850 million km away and appears 35 arcseconds wide through a telescope. Any decent telescope shows its parallel cloud belts, while binoculars reveal its four main moons which swap places from side to side of the disk as they orbit the planet in periods of between 1.8 and 17 days. | 0.869507 | 3.636902 |
Scientists using the Herschel space observatory have made the first definitive detection of water vapor on the largest and roundest object in the asteroid belt, Ceres.
Plumes of water vapor are thought to shoot up periodically from Ceres when portions of its icy surface warm slightly. Ceres is classified as a dwarf planet, a solar system body bigger than an asteroid and smaller than a planet.
Herschel is a European Space Agency (ESA) mission with important NASA contributions.
“This is the first time water vapor has been unequivocally detected on Ceres or any other object in the asteroid belt and provides proof that Ceres has an icy surface and an atmosphere,” said Michael Küppers of ESA in Spain, lead author of a paper in the journal Nature.
The results come at the right time for NASA’s Dawn mission, which is on its way to Ceres now after spending more than a year orbiting the large asteroid Vesta. Dawn is scheduled to arrive at Ceres in the spring of 2015, where it will take the closest look ever at its surface.
“We’ve got a spacecraft on the way to Ceres, so we don’t have to wait long before getting more context on this intriguing result, right from the source itself,” said Carol Raymond, the deputy principal investigator for Dawn at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. “Dawn will map the geology and chemistry of the surface in high-resolution, revealing the processes that drive the outgassing activity.”
For the last century, Ceres was known as the largest asteroid in our solar system. But in 2006, the International Astronomical Union, the governing organization responsible for naming planetary objects, reclassified Ceres as a dwarf planet because of its large size. It is roughly 590 miles (950 kilometers) in diameter. When it first was spotted in 1801, astronomers thought it was a planet orbiting between Mars and Jupiter. Later, other cosmic bodies with similar orbits were found, marking the discovery of our solar system’s main belt of asteroids.
Scientists believe Ceres contains rock in its interior with a thick mantle of ice that, if melted, would amount to more fresh water than is present on all of Earth. The materials making up Ceres likely date from the first few million years of our solar system’s existence and accumulated before the planets formed.
Until now, ice had been theorized to exist on Ceres but had not been detected conclusively. It took Herschel’s far-infrared vision to see, finally, a clear spectral signature of the water vapor. But Herschel did not see water vapor every time it looked. While the telescope spied water vapor four different times, on one occasion there was no signature.
Here is what scientists think is happening: when Ceres swings through the part of its orbit that is closer to the sun, a portion of its icy surface becomes warm enough to cause water vapor to escape in plumes at a rate of about 6 kilograms (13 pounds) per second. When Ceres is in the colder part of its orbit, no water escapes.
The strength of the signal also varied over hours, weeks and months, because of the water vapor plumes rotating in and out of Herschel’s views as the object spun on its axis. This enabled the scientists to localize the source of water to two darker spots on the surface of Ceres, previously seen by NASA’s Hubble Space Telescope and ground-based telescopes. The dark spots might be more likely to outgas because dark material warms faster than light material. When the Dawn spacecraft arrives at Ceres, it will be able to investigate these features.
The results are somewhat unexpected because comets, the icier cousins of asteroids, are known typically to sprout jets and plumes, while objects in the asteroid belt are not.
“The lines are becoming more and more blurred between comets and asteroids,” said Seungwon Lee of JPL, who helped with the water vapor models along with Paul von Allmen, also of JPL. “We knew before about main belt asteroids that show comet-like activity, but this is the first detection of water vapor in an asteroid-like object.” | 0.905804 | 4.001512 |
Scientists for the first time have detected water in the atmosphere of an Earth-like planet orbiting a distant star, evidence that a key ingredient for life exists beyond our solar system.
(Text from Reuters)
More than 4,000 exoplanets of all types and sizes have been detected overall.
The latest discovery was reported in research by a team of scientists at University College London (UCL) published in the peer-reviewed journal Nature Astronomy.
The findings were revealed from observations made with the Hubble Space Telescope, which analysed starlight filtered through K2-18b's atmosphere.
K2-18b orbits a dwarf star in the constellation Leo that lies 100 light-years from Earth.
While light from the sun takes several minutes to reach Earth, light from K2-18b's star takes a century to reach our planet, "so for us to travel it is impossible," Angelos Tsiaras, an astronomer at UCL, said.
"Given it's so far away we don't really have any other choice but stay on our own Earth, so it's important to make Earth great again rather than looking for an alternative to go to," Tsiaras said.
Aside from the tremendous distance separating Earth from K2-18b, the exoplanet is likely exposed to far more radiation than Earth, diminishing the prospects for life evolving there.
However, the discovery brings astronomers closer to answering the fundamental question of how unique Earth is in the universe, the scientists said. | 0.91578 | 3.223556 |
You must have seen the slightly blurry image of a black hole event horizon making the rounds on the internet in April. A bright, orange, cosmic doughnut. As an astronomer, this image was absolutely mind-blowing. In this post, I’ll share why this image is so important for science and its other benefits.
We are not actually “seeing” the black hole
I just wanted to clarify this important point because it is what is so mind-blowing about this picture. We are not seeing the actual black hole. We are seeing the boundary where light can’t escape from any more because of the black hole – called the ‘Event Horizon’. The ‘dougnnut hole’ at the centre is where light has been scooped out by the black hole’s extreme gravity. Because the gravity around a black hole is so strong, the light can’t escape that region and is trapped – causing the darkness at the centre. Black holes – as well as their event horizons – have a very small size relative to other astronomical objects, which adds to the challenge in observing them.
It shows us that the impossible isn’t always impossible
If you asked me, two years ago, whether we will ever manage to get an image of a black hole’s event horizon, my answer would have been a strong no. For most astronomers, the idea of ever getting this close to imaging a black hole would have seemed impossible. Since black holes don’t emit light and are so small – observing them was – for a long time – thought to be something we would never be able to do. We are in an era of science where the discoveries are completely blowing away our ideas of what is and isn’t impossible – and this is largely due to the work of many people.
It will help us understand different types of galaxies
My own studies focus on galaxies, so I find this particularly interesting. Some galaxies, like M87, have what is known as an ‘active galactic nucleus’. In other words, the black hole at the centre of the galaxy being ‘fed’ gas, stars, and other material through the disk surrounding it. This results in extremely large jets, being shot out from the central region surrounding the black hole. Since not all galaxies are active, having a measurement of an active black hole and – eventually when the Event Horizon Telescopes releases the image of our own, Milky Way galaxy’s black hole – a non-active black hole will help us understand the processes that create these Active Galactic Nuclei in a lot more detail.
We can use black holes to test gravity
Black holes were once only theoretical objects. They test our theories of gravity to the extreme. Although observations within our own galaxy showed stars orbiting something that could only be a black hole, having a picture of a black hole event horizon, which matches up with simulations and theoretical predictions so well, is a good sign that these extreme objects exist. This image is a strong indicator that Einstein’s theory of general relativity – which is what we use to explain gravity – is correct.
International collaboration is the path forward for science
The idea of the ‘lone genius’ – people like Einstein, Newton and Da Vinci who were thought to have worked on their own on amazing theories, making amazing discoveries – is dying out. The type of questions that we are asking nowadays in science is far beyond the scope of a single, brilliant mind. Taking pictures of black holes, detecting faint gravitational waves, building the world’s largest radio interferometer (a type of telescope that works by linking up multiple receivers), and detecting subatomic particles require many people all working together. Our world is increasingly divided over racial, political, economic and national lines. These big projects show us that when we put our differences aside and work together – we can do impossible things. | 0.861458 | 3.826109 |
Our visual reality, the physical world that we think we live in, comprises less than 5 percent of matter. Most of the universe is made up of an unexplained force responsible for its accelerated expansion: dark matter and dark energy. Their other properties are a mystery, which is why scientists would love to find out more. Russian scientists are launching a Proton rocket into space that will spend four years collecting data and hopefully crack the secrets of dark energy, and another three years doing follow-up observations.
Spektr-RG’s Mission In Space
The rocket called Spektr-RG was supposed to leave on its 4-year journey this June, but has been rescheduled to depart in July. (Spektr-R satellite telescope launched in 2011).
This will be the biggest Russian space mission in the last seven years. The program has roots in old USSR programs, which has been revived in 2005 on a smaller scale.
The Proton rocket was created by Russian and German manufacturers. It will fully scan the sky eight times with X-ray telescopes in order to measure distance and mass of clusters of galaxies in the universe. These clusters will help understand dark energy.
Dark Energy and The Universe’s Expansion
In the 1990s. The Hubble Space Telescope (HST) observed a supernova that showed the universe’s expansion is accelerating. The only theory as to why is dark energy, an unknown force. About 68 percent of the whole universe is dark energy; and we know almost nothing about it.
Albert Einstein was the person scientist to say that what looks like empty space in the cosmos is not nothing, but something of amazing properties if only it was understood. One of his theories on gravity is that there is a cosmological constant, the energy density, which means no matter how much energy is created out of space as the universe expands, it possesses same properties making everything accelerate faster.
A different theory is the quantum theory of matter, saying that “empty space” is filled with temporary particles that will eventually disappear. However, this theory did not add up when tested.
Third explanation is that the dark energy is a type of energy fluid or field that creates the expansion. Yet, that still leaves most questions unanswered of why it exists and does it interact with other matter.
The last explanation is the Einstein was wrong about gravity. Then a new gravity theory is needed to explain how galaxies come together in clusters, and for that new data is needed. Which is exactly what the Russia mission is hoping to achieve.
Spektr-RG will be observing black holes and cosmic structures with clouds of super-hot gas to gain more answers to the dark energy mystery.
“If you have an unbiased look at the whole sky, you have a potential for detections. We don’t know what we will see in the end,” said Peter Predehl, the head of the science team at the Max Planck Institute for Extraterrestrial Physics (the institute that designed the telescope).
“We designed the instrument for a specific reason, and this is in order to detect 100,000 clusters of galaxies, and that goes into the direction of (studying) dark energy.” | 0.838488 | 3.777764 |
Gibbous ♎ Libra
Moon phase on 23 March 2016 Wednesday is Full Moon, 15 days old Moon is in Libra.Share this page: twitter facebook linkedin
Moon rises at sunset and sets at sunrise. It is visible all night and it is high in the sky around midnight.
Moon is passing first ∠3° of ♎ Libra tropical zodiac sector.
Lunar disc appears visually 8.1% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1774" and ∠1924".
The Full Moon this days is the Worm of March 2016.
There is high Full Moon ocean tide on this date. Combined Sun and Moon gravitational tidal force working on Earth is strong, because of the Sun-Earth-Moon syzygy alignment.
The Moon is 15 days old. Earth's natural satellite is moving through the middle part of current synodic month. This is lunation 200 of Meeus index or 1153 from Brown series.
Length of current 200 lunation is 29 days, 9 hours and 29 minutes. It is 1 hour and 23 minutes longer than next lunation 201 length.
Length of current synodic month is 3 hours and 15 minutes shorter than the mean length of synodic month, but it is still 2 hours and 54 minutes longer, compared to 21st century shortest.
This lunation true anomaly is ∠339.5°. At the beginning of next synodic month true anomaly will be ∠355.6°. The length of upcoming synodic months will keep decreasing since the true anomaly gets closer to the value of New Moon at point of perigee (∠0° or ∠360°).
13 days after point of perigee on 10 March 2016 at 07:02 in ♈ Aries. The lunar orbit is getting wider, while the Moon is moving outward the Earth. It will keep this direction for the next 2 days, until it get to the point of next apogee on 25 March 2016 at 14:16 in ♎ Libra.
Moon is 404 032 km (251 054 mi) away from Earth on this date. Moon moves farther next 2 days until apogee, when Earth-Moon distance will reach 406 125 km (252 354 mi).
1 day after its ascending node on 22 March 2016 at 12:59 in ♍ Virgo, the Moon is following the northern part of its orbit for the next 13 days, until it will cross the ecliptic from North to South in descending node on 5 April 2016 at 17:27 in ♓ Pisces.
1 day after beginning of current draconic month in ♍ Virgo, the Moon is moving from the beginning to the first part of it.
7 days after previous North standstill on 16 March 2016 at 05:01 in ♋ Cancer, when Moon has reached northern declination of ∠18.206°. Next 7 days the lunar orbit moves southward to face South declination of ∠-18.239° in the next southern standstill on 30 March 2016 at 22:12 in ♐ Sagittarius.
The Moon is in Full Moon geocentric opposition with the Sun on this date and this alignment forms Sun-Earth-Moon syzygy. | 0.860247 | 3.171106 |
The highlight for our November 2019 Sky Watch is the Venus and Jupiter Conjunction on November 24. Here is your guide to view this spectacular sight and other bright planets in the night sky.
Sky Watch November 2019
by Bob Berman, as featured in The Old Farmer’s Almanac
The two brightest planets, Jupiter and Venus, pair up this month! They will be the first objects in the sky to pop out at dusk; just look west towards sunset.
- Dazzling Jupiter shines bright from dusk until early evening—and Venus sits below the Giant Planet most of the month.
- You’ll know which is which because Venus is the brightest planet in the sky and Jupiter is the second brightest (and brighter than any star).
November 24 Venus and Jupiter Conjunction
On Sunday, November 24, Venus and Jupiter meet up for a beautiful conjunction, hovering side-by-side in the west after sunset, but quite low in twilight.
Venus is not hard to find. It’s the brightest object in Earth’s sky (after the Sun and Moon).
At twilight, look in the direction of sunset (west) and quite low near the horizon. Make sure there is an unobstructed view.
Venus will be passing very near Jupiter, just 1.4 degrees south of the King Planet. Again, Venus will be the brighter object.
At Month’s End
At the month’s end, spectacularly-bright Venus will have moved above Jupiter—and she will reign once again over the night sky.
The Moon floats just above Venus on the 28th.
On November 1 and November 2, Saturn will be easy to find. Look for the crescent Moon and that’s Saturn nearby! Read more details on the Moon and Saturn meet-up.
For the rest of the month, Saturn shines brightly in the night sky, emerging after sunset and then dipping back below the horizon around 9 P.M.
The Ringed Planet isn’t as bright as Jupiter so use Jupiter to find Saturn. Put out your arm and make a fist. Saturn is a good two fist-widths to the east of Jupiter. The Ringed Planet will be the only bright “star” in that part of the sky.
- From the 1st to the 14th, returning Mars rises low in the predawn east, shortly before the Sun. The orange planet meets Virgo’s blue star, Spica.
- During the month’s second half, bright Mercury appears below Mars.
- On the 24th, the crescent Moon hovers to the left of Mars, with Mercury below.
- On the 25th, a predawn lineup has blue Spica highest, above orange Mars, then orange Mercury, and finally the Moon, lowest.
The big news this month is the Mercury Transit.
Mercury transits the Sun’s face on November 11, starting at 7:37 A.M. and continuing for over 5 hours.
As the planet shifts from the evening sky to the morning sky, it passes directly in front of the Sun’s disk, appearing as a small black dot.
All of the United States (except Alaska) and Canada can see at least part of it (a “solar telescope” and proper eye protection is required).
I’ll write more about this event in the next week.
The Full Moon of November
The Full Moon reaches peak fullness in the morning of Tuesday, November 12, at 8:34 A.M. EST. Look for it the night before or just after sunset on the 12th.
The Old Farmer’s Almanac calls this the Full Beaver Moon. See the November Moon Guide for facts and folklore.
Go to the Almanac rise/set calculator to find out when the Moon and planets rise and set in your sky. | 0.803397 | 3.196957 |
In 1998, the European Organization for Nuclear Research (CERN) began the construction of what became the largest machine ever built in human history. It would have a circumference of 27 km and would cost approximately $9 billion to construct. It was a particle accelerator and it was called the Large Hadron Collider (LHC). It was designed to solve some of the greatest mysteries in physics and give us a better understanding of the universe and its creation.
During its construction, millions of people were opposed to this monumental project. They feared the creation of micro black holes that would stabilize and consume the entire planet. To some extent, these fears were correct. When two particles collide, a micro black hole is created, yet these black holes quickly lose mass through Hawking radiation. As a result, they only last for fractions of a second.
To satisfy the public, CERN commissioned the Large Hadron Collider Safety Study Group (LSSG) to analyze the LHC and assess any possible danger. In 2003, the Group released their report entitled, Study of Potentially Dangerous Events During Heavy-Ion Collisions at the LHC, which concluded that 'there was no basis for any conceivable threat'. In 2008, CERN organized the Large Hadron Collider Safety Assessment Group (LSAG), who was tasked with reviewing the report made by the LSSG and to take into consideration new information that was not available or known in 2003.
LSAG supported the conclusions in the 2003 report, reaffirming that 'there was no basis for any conceivable threat.' They wrote another report, called Review of the Safety of LHC Collisions, which was reviewed and endorsed by CERN's Scientific Policy Committee. The report addressed concerns about cosmic rays, strangelets, vacuum bubbles, magnetic monopoles, and microscopic black holes.
According to the Standard Model, a theory concerning nuclear interactions, the minimum required energy to stabilize a micro black hole is 1019 GeV (one GeV is a billion volts). To put this into comparison, an average toaster oven operates at approximately 200 volts. In order to reach the minimum required energy, one would need 5*10^28 toaster ovens. There aren't that many toaster ovens in existence. In addition to this, we would require a ring accelerator that, with our current magnetic technology, would have a diameter of 1,000 light-years.
There are many theories on how to simplify these requirements, yet these theories aren't possible either with our current technology. One theory (Choptuik & Pretorius, 2010, pg. 1) states that if we added an extra dimension, the required energy would go down by half. The problem with that idea is that we don't know how to control and manipulate dimensions.
But, how could we create one? What are the specific technological requirements to create a black hole? And what threat would it possess if we made one? This is a difficult, obscure topic with no easy or direct answer and for now, we will only be able to theorize over the answers.
Section 1: Black Holes
Subsection A. What is a black hole?
A black hole is an area whose gravitational force is so powerful nothing can escape. Anything unfortunate enough to come close to a black hole will be sucked in and will be unable to escape the pull of gravity. Even light cannot escape the grasp of a black hole, which explains its moniker, black hole.
At the center of a black hole is a singularity, which is a point at which matter is compacted to where it has infinite density and zero volume. Around it is an event horizon, widely considered to be the boundary of a black hole. Once an object enters the event horizon, it will be pulled into the singularity and crushed into such a miniscule object that it is difficult to fathom the size of it. Imagine an object the size of our Sun becoming the size of a marble. This event horizon is dictated by a formula (1916) created by German physicist, Karl Schwarzschild (pg.5), which is shown below.
In this equation, R is the Schwarzschild radius, G is Newton's constant, M is the mass of the black hole, and c is the speed of light. The event horizon of the black hole must fall within the Schwarzschild radius or the black hole cannot exist. If the event horizon doesn't fall within the Schwarzschild radius, then the power of gravity isn't enough to create a singularity and a black hole won't form.
At this time, it should be admitted that, in theory, it is possible to escape the event horizon of a black hole. However, due to current technological restrictions, it is impossible for us to achieve this. This is because the escape velocity exceeds the speed of light, which supports the fact that light is unable to escape a black hole. Considering that we have yet to reach the speed of light, we cannot reach the required escape velocity. Here are three variations of the formula for calculating escape velocity:
In this equation, Ve is the escape velocity, G is the Gravitational Constant, M is the mass of the body being escaped from, r is the distance between the center of the body and point at which the escape velocity is being calculated, g is the gravitational acceleration at that distance, and ?? is the standard gravitational parameter.
Some of these things should be explained, since they aren't topics of common discussion. Firstly, the Gravitational Constant is a constant of proportionality used to calculate the gravitational force of various objects and is also known as Newton's Constant. It is equal to 6.67??10'11 m3 kg'1 s'2. Next, the gravitational acceleration is the rate of acceleration induced on an object by gravity. At different points on Earth, this can vary from 9.78 to 9.82 m/s2. Lastly, the standard gravitational parameter is the measure of the capacity of a celestial body to apply a Newtonian gravitational force on another celestial body.
Here's an example of this formula at work. Let us consider a spaceship on the event horizon of a black hole. First, we need to calculate the Schwarzschild radius of our theoretical black hole, which is going to have a mass of 20 solar masses (20*the mass of our sun).
From this equation, we find out that the Schwarzschild radius is 59044.46645m or 59km. This will act as r in our escape velocity formula. Now we can calculate the escape velocity of our
After solving this, we are left with the required escape velocity to escape from our theoretical black hole, which is 299,792,458m/s. To put it into perspective, the highest speed the human race has ever achieved is 24,791mph. This was achieved by the crew of the Apollo 10 in May, 1969. The required speed to escape a black hole is 186,347 miles per second, or 670,849,200 miles per hour. That's approximately 27,000 times faster than we have ever traveled.
Keeping that information in mind, it is fair to say that, for the time being, we cannot escape a black hole, and anything unfortunate enough to get too close, is sure to face certain doom.
Subsection B. How are black holes formed?
A black hole is formed after the supernova of a giant star, typically a star with over 3 solar masses. A supernova occurs when a star has used up all of its nuclear fuel. The star then releases a massive wave of energy, which is roughly equivalent to the power found in a 1028 megaton bomb (or a few octillion nuclear bombs).
There are two main types of supernovae. They are Type I and Type II. Type I supernovae have three subcategories: Ia, Ib, and Ic, which are divided according to their spectra. Most Type Ia supernovae originate from white dwarf stars which have reached the Chandrasekhar limit (which is the maximum size for a stable white dwarf star), or 1.39 solar masses.
Type II supernovae occur when a massive star (usually between 8 and 100 solar masses) reach the end of their lives. The star has burned all of its nuclear fuel and begins to collapse in on itself. If the core is less than about 3 solar masses, then it compresses into a core that is approximately 20 kilometers across and consists entirely of neutrons. This core is called a neutron star, and is so dense, that a teaspoonful of this material weighs 50 billion tons on Earth. However, if the core is greater than 3 solar masses, then the core will continue collapsing on itself and create a black hole.
Section 2: Particle Accelerators
Subsection A: An Overview of Particle Accelerators
In its simplest definition, a particle accelerator is a machine that accelerates atomic and subatomic particles at high velocities in order to solve mysteries about the creation of our universe, validate string theory, and find the answers to many questions that we have about the world around us. They vary greatly in size, with the largest being the Large Hadron Collider at CERN in Switzerland with a circumference of 27 kilometers, and the smallest being the Cornell device at Cornell University in New York that is only a few square centimeters.
There are several types of particle accelerators, including, but not limited to: cyclotrons, synchrotrons, and colliders. A cyclotron sends particles in a spiral path radiating outwards, while a synchrotron sends particles in a circle so that they almost reach the speed of light. A collider, which has no doubt become the most well known type of accelerator, sends atoms hurtling towards each other at high velocities and smashing them together.
Subsection B: Examples of Particle Accelerators
Since the dawn of the 20th century, there have been approximately 70 particle accelerators created in the world. A large portion of them receive no public attention whatsoever, despite many of them being large and expensive projects. The total cost of building them totals to several billions of dollars. Yet one accelerator has received more attention than the rest of them combined.
This accelerator is the Large Hadron Collider (LHC) at CERN in Geneva, Switzerland. It cost $4.4 billion to make and is now the largest machine in the world. When it was being built, much of the technology required for it to perform its duties had not been invented. Therefore, multiple side projects had to begin in order for the LHC to be created.
Few machines have created as much controversy as the LHC has. People feared the creation of micro-black holes, strangelets, and cosmic rays. Many staunch Christians thought that it was sacrilegious since one of the tasks of the LHC was to verify the Big Bang Theory. More articles have been written about the LHC than any other particle accelerator in the entire world. It attracts the attention of a very eclectic crowd of scientists, Christians, atheists, science fiction enthusiasts, and authors.
There are many other accelerators spread through the world. For example, there's the Cornell High Energy Synchrotron Source (CHESS) at Cornell University in New York, the Beijing Electron-Positron Collider (BEPC) in Beijing, the ISIS Neutron Source at Rutherford Appleton Laboratory in Oxford, and the Radioactive Ion Beam facility (RIBRAS) in S??o Paulo. All of these accelerators perform important and fascinating experiments that strive to define the boundaries of the world we live in.
Section 3: Creating a Black Hole
Subsection A: The LSAG Report
In 2003, CERN had received voracious attacks about the dangers of their project. People were terrified about the LHC being a doomsday machine that would bring about the end of the world. In order to bring these fears to a halt, they assembled a team of the most qualified physicists and astro-physicists in the world. This team was tasked with assessing the risks and dangers of completing the construction of the LHC. They were called the LHC Safety Study Group (LSSG). Their result was a report that directly stated that there was no threat of micro black holes, or strangelets.
In 2008, construction of the LHC had finished and in September, the first collision was performed. That same year, CERN organized another team of people to review the report written by the LSSG. This team was known as the LHC Safety Assessment Group (LSAG). They published a 15 page report entitled, Review of the Safety of LHC Collisions. This report supported the LSSG's conclusion that there was no danger presented by the LHC.
Subsection B: Required Energy and Formula
In 1974, famed physicist Stephen Hawking published a paper (Black Hole Explosions, 1974) about the existence of a new kind of radiation consisting of photons, neutrinos, and other particles, and emanating from black holes. This new radiation was named Hawking Radiation and is one of the largest obstacles for microscopic black holes seeking to become stable.
If a microscopic black hole were to be created in a particle accelerator, it would lose mass and evaporate. This would happen in less than a nanosecond. The lifetime of a black hole is determined by this equation:
where M is equal to the mass of the black hole in solar masses and the final result is in seconds. A micro black hole can have a mass of at least the Planck Mass (22 micrograms or 1.10602785*10^-38). If we put this into the equation, we find that the lifetime of a micro black hole with a mass of 23 micrograms is almost zero. Our theoretical black hole would evaporate almost instantaneously.
For the black hole to be created in the first place, the accelerator would have to collide the particles with 10^19 GeV of power. This is 10,000,000,000,000,000,000,000,000,000,000 volts of energy. This is ten times more than the Planck energy, which is 1.2*10^19 eV or 1,200,000,000,000,000,000,000,000,000,000 volts. The most powerful accelerator in the world is the LHC and it produces approximately 7 TeV, or 7,000,000,000 volts. The required energy is 1.428571429*10^21 times larger than the power produced by the most powerful accelerator in the world.
Section 4: Building Requirements
Subsection A: Technological Requirements
Our current magnetic technology does not fit the requirements for the task of creating a micro black hole. The LHC uses magnetic dipoles and they are some of the most powerful magnets in the world, producing 8.4 Tesla when operating at a current of 11,700 amperes. Each one of these magnets is 14.3 meters long and the LHC uses 1,232 magnets in total. Each magnet costs $520,750 each, making the total value of all of the magnets $641,564,000.
If we were to use the same magnets to create a micro black hole, we would need enough for an accelerator with a diameter of 1,000 light-years. Were this project to be undertaken, it would certainly become the largest manmade structure in this solar system. However, it is extremely unlikely that we would have enough resources to complete the accelerator.
The more probable solution would be to advance our magnetic technology, but progress in this field is slow. It is possible to increase the magnetic field of electromagnets by increasing the current flowing through them, but there are limitations to this. There is a maximum limit of magnetic lines of force that can be passed through the core material of the magnet. Any increase in current will result in a small increase in the magnetic field.
Subsection B: Amount of Materials Needed
It can easily be expected that the theoretical particle accelerator described in the previous subsection will require a large amount of materials to construct. The following calculation operates under the following conditions: the tube that the particles are fired down is the same diameter as the tube used in the LHC and it is made of solid steel.
In order to create an accelerator with the same specifications above, we would need 8.5734*10^39 lbs of solid steel. The process of creating steel requires large amounts of iron, a mineral that is in limited supply on Earth. It is possible to mine the iron that the Earth's core is composed of, but it is impossible to extract this iron without compromising the integrity of the Earth's crust. An alternate solution to that problem would be to begin mining operations on Mars, whose surface contains massive amounts of iron. However, it is unknown whether the total amount of iron on Earth and Mars will be sufficient for the construction of the accelerator.
Therefore, due to the amount of uncertainty associated with this, it can be stated that we do not have the required amount of materials to begin such a project.
The road to manmade black holes is littered with obstacles. They vary from the energy required to the dimensions of the actual accelerator to the technology we need. The solutions include more powerful magnets, new energy sources, interplanetary mining, but many of these ideas require technology and knowledge that we haven't acquired yet.
A very good question that must be faced before hypothesizing and attempting to find solutions is: why? Given the risk of a growing black hole that can escape our control, what cause do we have for trying this dangerous feat? Is science worth the potential destruction that a black hole can ravage? And a question for the day when we reach this technological level is: Just because we can, should we? While that day is far from today, it is something scientists must ask themselves with every great idea.
The final analysis is simple: we can't create micro black holes in our particle accelerators with our current technology. The requirements are too great for our abilities. The fears that are spawned by particle accelerators are easily dissipated when information comes forth that disproves our beliefs. This does, however, provide religious fundamentalists with further reason to continue to question and disapprove of what goes on in our laboratories across the world.
Yet, one thing is true. We cannot become too sure of ourselves. Many theories and even validated scientific facts have been disproven before. We are human and therefore prone to error. We cannot shun the possibility that even the greatest minds on our planet can sometimes be wrong. Nor should we forget that science is unpredictable and quite often, we may find that what we believe is wrong.
Source: Essay UK - http://www.essay.uk.com/free-essays/science/black-holes.php | 0.844627 | 3.41565 |
After comet Sliding Spring's Oct. 19, 2014 close flyby of Mars, NASA reports that
All three NASA orbiters around Mars confirmed their healthy status Sunday after each took shelter behind Mars during a period of risk from dust [from the comet's tail].
"Took shelter behind Mars"? These spacecraft are in orbit around Mars, constantly in motion, so they can't very well just pack up and move to the other side of Mars to avoid getting hit with the dust.
So my questions are: What exactly qualifies as taking shelter behind Mars? Does it simply mean being on the other side of the planet from the tail of the comet as dust from the tail passed Mars?
How did NASA get the (constantly in motion) spacecraft to hide behind Mars? I assume that the orbits had to be modified in advance of the comet's arrival. I picture some orbital modifications that changed the phase of the orbits of the satellites so that they would be on the other side of Mars as the dust flew by, perhaps also making the orbits more elliptical with the apsis behind Mars, allowing the satellites to spend additional time in Mars' protection.
Will these orbital modifications affect the ability of the spacecraft to fulfil their primary missions as they relate to Mars? I am not asking whether dust from the comet will affect the quality of the instruments on the spacecraft (indeed, this whole question focuses on steps NASA is taking to prevent that from happening) but whether the altered orbits the spacecraft have after their orbital modifications will affect their ability to pursue their primary missions (such as flying over different parts of Mars than was originally intended, which may or may not be beneficial to answering the questions the spacecraft were originally launched to answer. Although scientists are nothing if not resourceful and I'm sure any data that come from the spacecraft, whether intended or not, will lead to important discoveries). | 0.819625 | 3.204777 |
2I/Borisov likely formed in extremely cold environment, high amounts of carbon monoxide show
A galactic visitor entered our solar system last year – interstellar comet 2I/Borisov. When astronomers pointed the Atacama Large Millimeter/submillimeter Array (ALMA) toward the comet on 15 and 16 December 2019, for the first time they directly observed the chemicals stored inside an object from a planetary system other than our own. This research is published online on 20 April 2020 in the journal Nature Astronomy.
The ALMA observations from a team of international scientists led by Martin Cordiner and Stefanie Milam at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, revealed that the gas coming out of the comet contained unusually high amounts of carbon monoxide (CO). The concentration of CO is higher than anyone has detected in any comet within 2 au from the Sun (within less than 186 million miles, or 300 million kilometers) . 2I/Borisov’s CO concentration was estimated to be between nine and 26 times higher than that of the average solar system comet.
Astronomers are interested to learn more about comets, because these objects spend most of their time at large distances from any star in very cold environments. Unlike planets, their interior compositions have not changed significantly since they were born. Therefore, they could reveal much about the processes that occurred during their birth in protoplanetary disks. “This is the first time we’ve ever looked inside a comet from outside our solar system,” said astrochemist Martin Cordiner, “and it is dramatically different from most other comets we’ve seen before.”
ALMA detected two molecules in the gas ejected by the comet: hydrogen cyanide (HCN) and carbon monoxide (CO). While the team expected to see HCN, which is present in 2I/Borisov at similar amounts to that found in solar system comets, they were surprised to see large amounts of CO. “The comet must have formed from material very rich in CO ice, which is only present at the lowest temperatures found in space, below -420 degrees Fahrenheit (-250 degrees Celsius),” said planetary scientist Stefanie Milam.
“ALMA has been instrumental in transforming our understanding of the nature of cometary material in our own solar system – and now with this unique object coming from our next door neighbors. It is only because of ALMA’s unprecedented sensitivity at submillimeter wavelengths that we are able to characterize the gas coming out of such unique objects,“ said Anthony Remijan of the National Radio Astronomy Observatory in Charlottesville, Virginia and co-author of the paper.
Carbon monoxide is one of the most common molecules in space and is found inside most comets. Yet, there’s a huge variation in the concentration of CO in comets and no one quite knows why. Some of this might be related to where in the solar system a comet was formed; some has to do with how often a comet’s orbit brings it closer to the Sun and leads it to release its more easily evaporated ices.
“If the gases we observed reflect the composition of 2I/Borisov’s birthplace, then it shows that it may have formed in a different way than our own solar system comets, in an extremely cold, outer region of a distant planetary system,” added Cordiner. This region can be compared to the cold region of icy bodies beyond Neptune, called the Kuiper Belt.
The team can only speculate about the kind of star that hosted 2I/Borisov’s planetary system. “Most of the protoplanetary disks observed with ALMA are around younger versions of low-mass stars like the Sun,” said Cordiner. “Many of these disks extend well beyond the region where our own comets are believed to have formed, and contain large amounts of extremely cold gas and dust. It is possible that 2I/Borisov came from one of these larger disks.”
Due to its high speed when it traveled through our solar system (33 km/s or 21 miles/s) astronomers suspect that 2I/Borisov was kicked out from its host system, probably by interacting with a passing star or giant planet. It then spent millions or billions of years on a cold, lonely voyage through interstellar space before it was discovered on 30 August 2019 by amateur astronomer Gennady Borisov.
2I/Borisov is only the second interstellar object to be detected in our solar system. The first – 1I/’Oumuamua – was discovered in October 2017, at which point it was already on its way out, making it difficult to reveal details about whether it was a comet, asteroid, or something else. The presence of an active gas and dust coma surrounding 2I/Borisov made it the first confirmed interstellar comet.
Until other interstellar comets are observed, the unusual composition of 2I/Borisov cannot easily be explained and raises more questions than it answers. Is its composition typical of interstellar comets? Will we see more interstellar comets in the coming years with peculiar chemical compositions? What will they reveal about how planets form in other star systems?
“2I/Borisov gave us the first glimpse into the chemistry that shaped another planetary system,” said Milam. “But only when we can compare the object to other interstellar comets, will we learn whether 2I/Borisov is a special case, or if every interstellar object has unusually high levels of CO.”
The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.
One comet known as C/2016 R2 (PanSTARRS), which came from the Oort Cloud, had even higher levels of CO than Borisov when it was at a distance of 2.8 au from the Sun. | 0.913901 | 4.002418 |
The Coriolis force is a theoretical force used to account for the odd behaviour of objects which move far enough in rotating frames of reference. It is related to centrifugal force, and is a similarly convenient fiction.
The Coriolis effect - which the Coriolis force is often used to account for - is named after Gustave Gaspard Coriolis (1792-1843), the French mathematician and physicist who first described it in 1835 in a paper entitled On the Equations of Relative Motion of a System of Bodies.
Newton's Laws and Frames of Reference
Newton's Laws apply, in full and unmodified, in an inertial frame of reference. This means that if the place where you are doing your experiments is either standing still, or is in uniform motion, ie not accelerating or decelerating in a straight line, all your experiments will agree with Newton's Laws. However, if your 'lab' is undergoing any kind of acceleration, either in a straight line or in a curve ie, it's either rotating, orbiting a point or simply moving in curve, you will notice some strange effects.
An example of an inertial frame of reference is the whole universe (as far as we know...). Unless you have some seriously accurate measuring equipment, another example of an inertial frame of reference is a room in your house. Even though your front room is on the surface of the Earth, and the earth is rotating, practically any experiment you do will suggest your frame of reference is inertial.
However, if you take the whole planet as your lab, things are very different. The Earth is most definitely a rotating frame of reference, and some of the effects of that are very odd indeed.
How to Tell if You're in a Rotating Frame of Reference
As stated above, in ordinary life, just walking around, we usually think we're in an inertial frame of reference. Things stay still until you push them, and when they move, they generally move in a straight line unless acted on by some other force. This is the first of Newton's Laws, and without it snooker would be impossible, or at the very least a lot more difficult. All these things reliably apply to most stuff at the scale of a single human.
However, since we're on the surface of a spinning sphere, we're actually in a rotating frame of reference all along. To us on Earth this is actually fairly obvious: one glance up into the sky won't tell you, but another six hours later should give you a fairly hefty clue. The sun and stars demonstrate to us that our planet is rotating, and eventually Copernicus took the hint by looking at the paths that the other planets seem to take in the sky. But if we (like the people of the planet Krikkit in Douglas Adams' Life, the Universe and Everything) lived on a planet inside an opaque dust cloud, with no outside cues to help us realise our frame of reference was in fact rotating, would we be able to do an experiment to tell?
Well, the answer is yes - but in essence, a very simple experiment. Stand at the equator1 and fire a missile. Aim it to land exactly one thousand miles away. If you fire it due east or due west, you will note that it lands one thousand miles away in a straight line in the direction you aimed it. So far, exactly what you'd expect.
Now fire another identical missile one thousand miles due north. You will now note with some surprise that it didn't land a thousand miles away, and despite your perfect aim and the complete absence of any wind, it didn't land due north of your position either. Instead, it appears to have veered off to the west. Why?
A simple way of interpreting this occurrence is that some force diverted your missile. To you, standing on the ground, some force is surely required to explain the fact that the missile didn't travel in a straight line as predicted by Newton's first law. But what generated this force? To an outside observer, however, in an inertial frame of reference, the truth is clear. Your missile travelled in a perfectly straight line - but while it was up in the air the ground moved beneath it, so that it landed on a different line of longitude than the one it took off from.
Of course, since you are moving along with the ground, you cannot directly perceive this. You can however, infer it from the behaviour of other objects.
The Dead Giveaway
So, does Coriolis force actually exist? No. Real forces, like gravity, have a source, such as mass. Coriolis force is, like centrifugal force, a convenient fiction designed to account for the discrepancy between the normally reliable Newton's first law, and actual experience in rotating frames of reference. The dead giveaway here is that Coriolis force is a 'force' which applies to things you throw to the north, but not things you throw to the east, and you can't have laws which work in one direction, but not another: this is akin to having, say, gravity affecting things in the northern hemisphere, but not in the southern hemisphere - unthinkable.
If it Doesn't Exist, Why Does it Have a Name?
Coriolis force is as the title says, a convenient fiction. Using equations which include Coriolis force can simplify many calculations, including weather prediction and trajectories of ICBMs (Inter-continental Ballistic Missiles).
To experience Coriolis force for yourself, try throwing a tennis ball to a friend while you both ride on a roundabout. For maximum effect, don't stand opposite one another.
So That'll Explain the Bathwater Swirling, Then?
It is often said that it is possible to tell which hemisphere you're in by looking at the direction in which bathwater swirls down a plughole. This is put down to the Coriolis effect, but on the day to day, normal human scale of things, the Coriolis effect is tiny. This is one of the reasons why nobody noticed it until 1835. In fact, other factors such as how the bath was filled, who got out of it and how long ago, and the precise shape of the bath will have a much greater effect on the direction in which the water swirls.
Will it Ever be a Problem?
For most people, the Coriolis effect is something they will never notice. However, it is reasonable, if a little optimistic, to assume that at least one person who reads this Entry will spend some time in a spacecraft which simulates gravity by spinning. Unless that spacecraft is enormous, Coriolis effects will be immediately obvious to anyone who tries to spin around in a swivel-chair: they'll fall over. For this reason, there may be pressure to build ever larger habitats, until the 'threshold of obviousness' for Coriolis effects is passed. | 0.807326 | 3.602021 |
There is no need to tether a massive cable to the Earth’s surface if you can “dangle” it into Earth’s orbit from the Moon, a group of Columbia University scientists say. It would be difficult, but not impossible.
Scientists have come up with an interesting twist on the old concept of space lift, which should, in theory, significantly cut the cost of future Lunar missions, The Daily Star reported Thursday.
In a traditional space lift, a cable connects Earth’s surface to an object in geostationary orbit, allowing space missions to avoid using jet-powered rockets. A cable that could work in this context is impossible to build at this moment, as it would be too heavy to support its own weight. Scientists are now looking to carbon nanotubes, but the tech is not yet formalized.
A newly proposed project called Spaceline, however, uses a different approach, instead suggesting tethering the cable to the Moon, causing it to “dangle” into Earth’s gravity well.
“The movement of people and supplies along it are much simpler and easier than the same journey in deep space,” said Zephyr Penoyre, a Columbia University graduate astronomy student behind the project.
According to scientists, this would significantly reduce the load on the cable, making its creation possible at the current level of technology. The cable does not need to be thick; on the contrary, it is preferable to make it as thin as possible so that its weight is reduced and, therefore, gravitational pull as well.
“A cable which only hangs into Earth’s gravitational well need not be thick or massive,” Penoyre said in a draft paper, according to The Daily Mail. “It is optimal to make it as thin as possible as it extends closer to Earth. This means that the gravitational forces the cable feels, and thus the tension, is much reduced.”
Astronauts would still need to hop into space using conventional rockets, but, as soon as they reach the docking station at the end of the cable, they could simply take a vehicular ride via a solar-powered shuttle, the project implies. The ride, however, could take several days or even a week, so the shuttle must be able to provide life support.
The scientists acknowledge certain problems with their idea, the biggest being cable maintenance. Since there’s a lot of stuff flying in space between the Earth and the Moon, objects will inevitably hit the cable, damaging it, and this must be taken into account. Scientists suggest the creation of a multiple thread cable, which would support the load even if one or two threads are broken.
The other problem, of course, is cost, which is estimated to be measured in billions of dollars. Still, while this sum is vast, it is not impossible.
“Building a spaceline would be a huge engineering challenge, stretching the limits of current human capacity — but not exceeding them,” the researchers wrote. “A billion dollar price tag is not unattainable — and the possibilities of what could be done with such a structure may quickly pay dividends.”
Scientists believe that the cost of the project could be mitigated by the profits a functional lunar colony may potentially provide, as there are Helium 3 deposits which could theoretically solve Earth’s energy problem for several millennia.
The research, which has not yet been peer-reviewed, is being prepared for submission to the journal Acta Astronautica, The Daily Mail report says. | 0.902668 | 3.107558 |
Well, here we are again waiting for the clouds to go away and now have to contend with "June Gloom", but we can still review some astrophysics of curved space and supernova explosions and enjoy the jazz festival under cloudy skies.
We look forward to the OCA Astroimagers SIG, this Wednesday, where we will hear what other travelers are planning to do to view the July total solar eclipse in Chile. In the meantime, as we prepare to attend the Hartlefest, celebration of Jim Hartle's 80th birthday, we continue on our review of general relativity from his classic textbook on gravity. Keep in mind that astronomical and cosmological observations and theories are attempts to get at the nature of our universe and whether or not the space that we inhabit is flat or curved. Mathematical theories of geometry of space tells us that space can be positively curved flat or negatively curved as illustrated in the drawing below, taken from Hartle's class textbook.
|Mathematical possibilities for the geometry of space (Source: J. Hartle, "Gravity: An Intro to Einstein's General Relativity")|
Current astrophysical measurements indicate that the geometric space of our observable universe is pretty flat within a small margin of error. This means our universe is defined by the nature illustrated in the middle portion of the diagram above. You might wonder how the evolution of the universe can be predicted and calculated? Well, keep reading in Chapter 18 and beyond in the Hartle textbook and you will be able to begin to get a handle on how general relativity can make such predictions. The Friedman equation, a differential equation, which is derived from general relativity for an isotropic, homogeneous universe, can be used, once the total amount of matter, radiation and dark energy are entered, to predict the evolution of the universe. We can also tie the concept of redshift, z, together with the scale factor, a, for the size of the universe. At the current time, a = 1, and for earlier times, say for z = 1100, when the CMB was released, the universe would have been much smaller, in fact, we can calculate a = 1/ (z+1), a = 1/ 1101, which means the universe was just one thousandth as big at the time the CMB was released.
Similarly, if we look to the future, what this means for the future of flat universes, like our universe, is that it most likely continue expanding forever. If the space were positively curved, as illustrated in the leftmost case of the diagram above, and if the universe is dominated by normal matter, then it would be possible for the universe to eventually cease expanding, slow down and reverse course and eventually return in a "big crunch."
Well, it seems that our fate is not going to be that as illustrated in the left had portion of the diagram below. In a matter dominated universe, with positive curvature, the big bang would have expanded, but then depending on how much matter was present, the bang would have re-collapse. Luckily, we don't seem to live in that kind of universe. So in our flat universe the future coarse of expansion is expected to just continue expanding forever. Other diagrams and calculations in the textbook illustrate what happens assuming different amounts of dark matter and radiation and dark energy. What you see right away by examining various combinations of matter and energy is that in order to match the measured flatness of the universe and to account for the measured acceleration of the universe, that their is this mysterious dark energy component. With the recent recognition that the expansion is accelerating, the expansion goes on at a faster and faster rate.
Ok, enough of that, so says Astronomer Assistant Ruby who wants to go out and about. On our journey outside, she spies a plastic straw in the rain gutter and stops to ponder the consequences. Now, I was normally quite skeptical of restaurants that limit the availability of plastic straws, saying that they could end up as plastic pollution in the oceans. But here was an example of a straw in the gutter some dozens of miles from the ocean, so it seems it is quite possible for straws to enter the ocean, even from miles away.
|Astronomer Assistant Ruby pauses in front of a plastic straw in gutter (Source: Palmia Observatory)|
Yep, further down the road we see the sign saying that the storm drain does indeed drain to the ocean. So, yes, it seems that straws and other plastics can indeed find their way to the ocean even when they originate from miles away from the sea shore.
|Yep, you have seen these signs about draining to the ocean (Source: Palmia Observatory)|
After our walk and discovering the straw (and yes, in case you are wondering, I picked up the straw), we received an email and question from Still into Control, Gene, who asked about the possible effects on the Earth of a nearby supernova. He had heard, as I had heard and read many times, that a nearby supernova would pretty much burn up the Earth and yet Gene referred to an article that said if some nearby star like Betelgeuse were to blow up that it was too far away to do much damage. Is this the case? Hmm, I don't know but I guessed that as a physicist wannabe or senior physics student that we could do some back of the envelope calculations and get an answer. So, let's get to it!
So, starting with the light curve data for typical supernova and if we know how far away the supernova is then we can calculate the energy flux received here on Earth. So, we have:
- Supernova 10 to the 10th power brighter than the sun
- The sun luminosity is 3.82 time 10 to the 26th power watts
- Betelgeuse is approximately 222 parsecs from Earth
- One parsec is about 3.26 light years or 31 times 10 to 12th power kilometers
- Betelgeuse is current magnitude 0.5 star with luminosity about 100,000 that of the sun
- The sun's apparent magnitude is -26.4
- The moon's apparent magnitude is -12.6
|Supernova Light Curves (Source: www.hyperphysics.phy-astr.gsu.edu)|
So, this back of the envelope calculation, which neglects any light spectrum effects or asymmetric beaming effects, indicates that we wouldn't experience a lot of hurt. For instance, it is not clear if the estimate of luminosity of supernovas includes the energy released as neutrinos. Neutrinos are expected to be the majority of energy released and if that energy if already included in the luminosity estimate, then the amount of visible radiation received here would be much less and overall less impact on us Earthlings. Anyway thanks for triggering the question, Gene!
Ok, after all of that mental gymnastics, we need to get some rest and take it easy. It is still cloudy outside, but the Hyatt Regency Jazz Festival in Newport Beach is going full swing this weekend. So, as you can see, the skies are cloudy
|Can't see stars in the sky, but jazz stars show up on Newport Beach Festival stage (Source: Palmia Observatory)|
Even during the daytime, the skies are still cloudy. In between musical sets and between walking to the bar for refreshments we found an opportunity to have fun and pose in front of one of the signs looking out over the grounds to the harbor beyond.
Our favorite performers included the likes of Morris Day and the Time; Poncho Sanchez; Jeffrey Osborne; Nick Colionne; David Benoit and Mark Antonine. The festival finished up George Benson who eventually got everyone up off their chairs and dancing in the aisles and us ready to return to the observatory to rest up.
|Jazz master George Benson closes out Hyatt Regency Newport Beach Jazz Festival (Source: Palmia Observatory)| | 0.842442 | 3.859221 |
News Service Cornell University Contact: David Brand Office: (607) 255-3651 E-Mail: [email protected] FOR RELEASE: Dec. 1, 1999
On Friday, Polar Lander descent camera will capture Martian surface as never seen before: from only a few feet up
ITHACA, N.Y. -- For just under two minutes, shortly before 3:14 p.m. Eastern Time on Friday, Dec. 3, a camera directed toward the south polar region of Mars will capture and store a series of about 20 images unique in the annals of planetary exploration: the surface of a planet (other than the moon) as seen from altitudes ranging from about 4 miles to only about 30 feet.
The camera, known as the Mars Descent Imager, or MARDI, will be positioned between the legs of the Mars Polar Lander, with the exhaust of the hydrazine engines in view. It will begin clicking its shutter after the lander vehicle's heat shield has been jettisoned -- about 6.5 kilometers (about 4 miles) above the surface -- and while the craft is still swinging on its parachute harness. The last few images -- perhaps eight -- will be captured after the parachute has been jettisoned at about the 1 kilometer (.62 mile) altitude and as the craft makes a controlled descent, slowed by retro rockets, to the frigid northern edge of the Martian south pole's layered terrain.
"MARDI's images will make all of us much more comfortable in making interpretations of the lander's pictures because they will give us a context," says Peter Thomas, a senior researcher with Cornell University's astronomy department. "For the first time we will have a complete scale of pictures of Mars, from less than a millimeter all the way up to orbiter pictures." The camera has a 70-degree field of view, and the estimated difference in resolution between the first and the last black-and-white images will be a factor of about 800.
Thomas is one of three Cornell researchers on the MARDI team, led by Michael Malin, president of Malin Space Science Systems, San Diego. Also participating in the development of the imaging system, and present at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., to interpret the images after they are received from the Mars Polar Lander, are Cornell astronomy professors Joseph Veverka, who also is chair of the Cornell astronomy department, and Steven Squyres. Also on the team are M.A. Caplinger of Malin Space Science and M.H. Carr of the U.S. Geological Survey in Flagstaff, Ariz. MARDI was developed under a $3.5 million JPL contract.
At present, the highest-resolution images of the Martian surface, taken from orbit, are made up of pixels (or picture elements) each covering 1 1/2 yards of terrain. That is about to change dramatically to images with each pixel covering a fraction of an inch of the surface.
The descent camera pictures will be used to interpret ground features and will aid in the mission's main purpose, studying the layers of ice and dust covering the polar region. These images will be captured with a "nesting" technique, meaning that each successive image will be nested within the previous picture. As the spacecraft loses altitude, each successive image will cover a smaller area within the previous larger image. The camera has no ability to aim, but simply points where the spacecraft points. "The first image will be several kilometers on one side, but the camera has a fairly wide angle so that even with the spacecraft swinging on a parachute, the images should remain nested within one another," says Thomas.
The nesting technique, he notes, will enable researchers to find a ground feature, such as a boulder, in the image taken closest to the ground, then work back to the largest picture. The spacecraft's electronic memory retains each image, plus details of when the image was taken, which direction the spacecraft was pointing at the time and its altitude. In this way, says Thomas, "you can take pictures and reconstruct them from that geometry."
The number of images returned to JPL will be limited by the storage capacity of the spacecraft's memory. For this reason, the on-board computer has been programmed both to reject some images taken by the camera and to write over others. The computer will be instructing the camera to capture images in different image formats (in terms of pixels) based both on altitude and the number of images already taken. If the computer determines that the altitude has not changed sufficiently, it will not save the image.
"If the memory's storage is full and the camera is still taking images, the computer is programmed to throw out some lower-resolution pictures," says Thomas. "We want to maintain nesting and protect the higher resolution images as we get really close to the surface. Those images closer to the surface are of platinum value."
The "overwhelming purpose" of the descent camera's images, says Thomas, is to tie what will be seen with the lander's camera on the surface of Mars with images taken a few feet from the surface. "We've seen the whole of Mars in 100-meter resolution, but only 1 percent of the surface in three-meter resolution. These images will be filling the gap."
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Bakersfield Night Sky – July 15, 2017
By Nick Strobel
“Twinkle, twinkle little star, how I wonder what you are.” Cute song and a lot of astronomy in it! During this past couple of weeks, I visited family in Oregon and took walks with my wife in some beautiful green places. On one of those walks she suggested I write about why stars twinkle and what would the constellations look like from one of the other planets in our solar system. In my astronomy class, we spend about half a lecture on the effect of the atmosphere on star light, one week on how we measure the properties of the stars, and another week on the structure of stars and how they shine. Let’s take a closer look at “twinkle little star” but brief enough to fit within the space of a newspaper column.
Our atmosphere makes it possible for life to exist on the surface of Earth but it sure is a nuisance for doing astronomy. The air above is made of ever-shifting layers of gases of varying temperatures and densities that cause light rays to bend and scatter about. Like looking at someone standing at the edge of a swimming pool while you’re under water, the stars shimmer and dance about as we look at them from the surface of Earth. Since at least ninety percent of our atmosphere is within about ten miles of the surface, the shimmering—twinkling— is noticeably lessened from the top of a tall mountain, just a couple of miles above sea level.
Under high magnification, the pretty twinkling star is revealed to be a fuzzy blob made of many tens to a few hundred distorted images of the pinpoint star that shift wildly about in fractions of a second. I show a real-time video of a high-magnification image of a double star to my astronomy classes and wish them good luck in seeing a double star in all that mess. I have a link to that video in the telescope chapter of my Astronomy Notes website if you want to try finding the double star in the fuzzy blob.
Astronomers have figured out how to remove the effects of the turbulent atmosphere. When I was an undergraduate, a computer-intensive image processing technique called speckle interferometry was used to recover the true image of the objects we were looking at. That was replaced by something called “adaptive optics” which uses thin mirrors that can be quickly deformed to counteract the distortion of the star light by the atmosphere.
Large telescopes on the ground are now able to achieve images of some objects that are sharper than those from the Hubble Space Telescope. Hubble can make super-sharp images for any object and it has a truly black sky background. It also can observe over a larger swath of wavelengths, from UV to near-infrared, than what telescopes can do from the ground.
We find out that the stars are giant nuclear fusion reactors by measuring their distances from us and spreading out the star light into a rainbow of colors to make a spectrum. For the nearby stars we can use a technique called trigonometric parallax to measure their distances, that is similar to what surveyors use to measure large distances on Earth. From the database of nearby star distances, we can calibrate how star brightness changes with distance, so that we can use star brightness to determine a very distant star’s distance.
Putting a star’s brightness together with its distance enables us to find out the star’s true power output—the wattage of those big light bulbs. The rainbow spectrum enables us to measure the temperature of stars extremely accurately. Even the coolest and dimmest stars have a power output of six followed by twenty-two zeroes watts and are over a couple thousand degrees Celsius on their surface.
We find out how much material they contain (their mass) by measuring how much the star changes the motions of objects near it. Usually the other object near the star is another star, so the measurements give us the total combined mass of the two stars. Then measuring how much each star moves relative to its companion star, enables us to proportion out how much of the total mass goes with each star. Even the smallest star has a mass eighty times greater than Jupiter.
Using the laws of gas physics we can figure out what the conditions are like in the centers of stars. The density of the gas is greater than the densest rocks and metals and the temperature is above eight million degrees Celsius. Super-hot and super dense gases are just the thing you need for nuclear fusion, where low-mass atomic nuclei like hydrogen are smashed together to make higher-mass nuclei plus some energy as described by Einstein’s famous equation, E = mc2. Measuring the particles called neutrinos confirms that nuclear fusion is occurring in the star cores. If you want just a wee bit more detail about how we figure out what stars are like, then see my Astronomy Notes website. “Twinkle, twinkle little star, now I know what you are (and you’re not that little).”
Now for the view of the constellations as seen from other places in our solar system. Our solar system is so very teeny, tiny in comparison with the distances between the stars, that Pluto’s view of the constellations is the same (very, very nearly exactly so) as what we see from Earth. I illustrate this in one of the field trip Planetarium shows. Even the view from the nearest star to the sun, the Alpha Centauri system, is very similar to what we see from Earth.
At the end of the month, Saturday July 29, will be another free public star party hosted by the Kern Astronomical Society at Panorama Park near where Linden Ave runs into Panorama Drive. Stop by between sunset and 10-ish for a free look through their telescopes. Did I mention that it is free?
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com | 0.838996 | 3.555082 |
eso1519 — Science Release
The Dark Side of Star Clusters
VLT discovers new kind of globular star cluster
13 May 2015
Observations with ESO’s Very Large Telescope in Chile have discovered a new class of “dark” globular star clusters around the giant galaxy Centaurus A. These mysterious objects look similar to normal clusters, but contain much more mass and may either harbour unexpected amounts of dark matter, or contain massive black holes — neither of which was expected nor is understood.
Globular star clusters are huge balls of thousands of stars that orbit most galaxies. They are among the oldest known stellar systems in the Universe and have survived through almost the entire span of galaxy growth and evolution.
Matt Taylor, a PhD student at the Pontificia Universidad Catolica de Chile, Santiago, Chile, and holder of an ESO Studentship, is lead author of the new study. He sets the scene: “Globular clusters and their constituent stars are keys to understanding the formation and evolution of galaxies. For decades, astronomers thought that the stars that made up a given globular cluster all shared the same ages and chemical compositions — but we now know that they are stranger and more complicated creatures.”
The elliptical galaxy Centaurus A (also known as NGC 5128) is the closest giant galaxy to the Milky Way and is suspected to harbour as many as 2000 globular clusters. Many of these globulars are brighter and more massive than the 150 or so orbiting the Milky Way.
Matt Taylor and his team have now made the most detailed studies so far of a sample of 125 globular star clusters around Centaurus A using the FLAMES instrument on ESO’s Very Large Telescope at the Paranal Observatory in northern Chile .
They used these observations to deduce the mass of the clusters and compare this result with how brightly each of the clusters shines.
For most of the clusters in the new survey, the brighter ones had more mass in the way that was expected — if a cluster contains more stars it has greater total brightness and more total mass. But for some of the globulars something strange showed up: they were many times more massive than they looked. And even more strangely, the more massive these unusual clusters were, the greater the fraction of their material was dark. Something in these clusters was dark, hidden and massive. But what?
There were several possibilities. Perhaps the dark clusters contain black holes, or other dark stellar remnants in their cores? This may be a factor that explains some of the hidden mass, but the team concludes that it cannot be the whole story. What about dark matter? Globular clusters are normally considered to be almost devoid of this mysterious substance, but perhaps, for some unknown reason, some clusters have retained significant dark matter clumps in their cores. This would explain the observations but does not fit into conventional theory.
Co-author Thomas Puzia adds: “Our discovery of star clusters with unexpectedly high masses for the amount of stars they contain hints that there might be multiple families of globular clusters, with differing formation histories. Apparently some star clusters look like, walk like, and smell like run-of-the-mill globulars, but there may quite literally be more to them than meets the eye.”
These objects remain a mystery. The team is also engaged in a wider survey of other globular clusters in other galaxies and there are some intriguing hints that such dark clusters may also be found elsewhere.
Matt Taylor sums up the situation: “We have stumbled on a new and mysterious class of star cluster! This shows that we still have much to learn about all aspects of globular cluster formation. It’s an important result and we now need to find further examples of dark clusters around other galaxies.”
Up to now astronomers have studied star clusters to this detail only in the Local Group. The relatively small distances make direct measurements of their masses possible. Looking at NGC 5128, which is an isolated, massive elliptical galaxy just outside the Local Group about 12 million light-years away, they were able to estimate masses of globular clusters in a completely different environment by pushing VLT/FLAMES to its limits.
The FLAMES observations provide information about the motions of the stars in the clusters. This orbital information depends on the strength of the gravitational field and can hence be used to deduce the mass of the cluster — astronomers call such estimates dynamical masses. The light gathering power of a 8.2-metre VLT Unit Telescope mirror and FLAMES’s ability to observe more than 100 clusters simultaneously was the key to collecting the data necessary for the study.
This research was presented in a paper entitled “Observational evidence for a dark side to NGC 5128’s globular cluster system”, by M. Taylor et al., to appear in the Astrophysical Journal.
The team is composed of Matthew A. Taylor (Pontificia Universidad Catolica de Chile, Santiago, Chile; ESO, Santiago, Chile), Thomas H. Puzia (Pontificia Universidad Catolica de Chile), Matias Gomez (Universidad Andres Bello, Santiago, Chile) and Kristin A. Woodley (University of California, Santa Cruz, California, USA).
ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.
Matthew A. Taylor
Pontificia Universidad Catolica de Chile
Thomas H. Puzia
Pontificia Universidad Catolica de Chile
ESO, Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591 | 0.86618 | 3.910597 |
LightSail 2 deployed it solar sail five months ago, and it’s still orbiting Earth. It’s a successful demonstration of the potential of solar sail spacecraft. Now the LightSail 2 team at The Planetary Society has released a paper outlining their findings from the mission so far.
The solar sail concept has been around for a while, all the way back to Johannes Kepler, in fact. Back in 1607 Halley’s comet passed overhead, and Kepler noticed how the comet’s tail streamed away from the Sun. He thought, correctly as it turns out, that sunlight was responsible. In a letter to Galileo that’s kind of famous in astronomy circles, Kepler said, “Provide ships or sails adapted to the heavenly breezes, and there will be some who will brave even that void.” Pretty cool.
Of course there was no way for Kepler to know how right he was. But now, thanks to The Planetary Society and others, we do.
The Planetary Society is a pioneer in the solar sailing field. LightSail 2 is actually their third solar sail spacecraft, following in the footsteps of LightSail 1, and their original precursor the Cosmos 1, which didn’t reach orbit when its launch rocket failed. A third solar sail spacecraft, called LightSail 3, will reach the Sun-Earth libration point L1 if all goes well.
As one of the first solar sail spacecraft, LightSail 2 is teaching us valuable lessons about solar sailing’s potential and limitations. On January 10th, the Planetary Society released a paper outlining some of those lessons. The paper is titled “Orbit and Attitude Performance of the LightSail 2 Solar Sail Spacecraft.”
LightSail 2 is slowly succumbing to drag, and making its way closer to Earth. When it was deployed, orbital modeling predicted that it would fall to Earth about one year after its sails were deployed. But the spacecraft is in a high-Earth orbit at about 720 km (447 miles,) much higher than other satellites and spacecraft like the International Space Station, which orbits at 400 km (249 miles.)
There’s relatively little data on atmospheric density at that altitude, and on the resulting orbit decay, so the one year prediction wasn’t precise. But thanks to LightSail 2, we now know that atmospheric drag at that altitude is strong enough to pull LightSail 2 toward Earth.One of the reasons for that is the spacecraft is not always solar sailing.
During each 100 minute orbit, LightSail 2 spends only about 28 minutes capturing solar photons, and that’s the only time it can change its trajectory. The rest of the time is spent either in eclipse, moving directly towards the Sun, or adjusting its orientation. That 28 minutes of actual sailing time is not enough to fully counteract the atmospheric drag.
That’s just one of the things The Planetary Society has learned from their LightSail 2 project. But within those orbits, there are other variables.
The team compared LightSail 2’s performance when it was randomly oriented vs when it was actively oriented for solar sailing. They found that when the spacecraft was randomly oriented, the semi-major axis of its orbit decreased by 34.5 meters per day. When it was actively oriented, the same measure shrank by only 19.9 meters per day. But there’s a lot of variation in its orbit, and sometimes the tiny spacecraft increased its orbit by 7.5 meters per day.
The video shows one single orbit for LightSail 2. Notice the red and blue lines superimposed on the spacecraft. The red line shows the direction of the Sun, and the blue line is the direction of the local magnetic field. When approaching the Sun, the spacecraft feathers its sails, and when it’s actively sailing, it turns its sails to catch the Sun’s photons. The Sun to -z angle changes from roughly 90 degrees to roughly 0 degrees.
In general terms, solar sailing can’t overcome atmospheric drag, but that’s not what these spacecraft are really designed for. Their potential lies in interplanetary travel, free from atmospheres and planetary eclipsing effects. NASA’s NEA Scout (Near Earth Asteroid Scout) spacecraft will spend two years under solar sail propulsion to reach an asteroid, though it will receive an initial propulsion boost from cold gas thrusters.
LightSail 2’s apogee and perigee have been cycling up and down over the five months since its deployment. Immediately following deployment, the spacecraft raised its apogee, making it the first solar sail spacecraft to do so. At the same time, the perigee decreased. It experienced a reversal of the trend in late October, and a reversion in December.
There are a couple reasons why the orbit goes through these cycles. Firstly, the Earth is an oblate spheroid, not a sphere. That means its diameter at the equator is about 42 km (26 miles) larger than at the poles. That makes the spacecraft experience precession, or wobbliness.
The second reason for LightSail 2’s apogee/perigee cycles is the Earth’s path around the Sun. That motion changes the angle between the Sun and the positions of the spacecraft’s apogee and perigee.
LightSail 2 is a great demonstration spacecraft, but it does have limitations. One of those is its single momentum wheel. The spacecraft uses that wheel to orient itself either parallel or perpendicular to the Sun’s rays, depending on whether its feathering its sails or actively sailing. Initially, ground crew were doing this manually, which was not efficient. Now they’ve automated the process, and the spacecraft is performing better as a result.
But throughout that process, the team learned one of their valuable lessons. Frequent changes in sail orientation imparts significant momentum to the spacecraft. One of the key technical challenges is managing that momentum.
Another lesson involves solar power. The solar sails are strictly for solar sailing. LightSail 2 has some very small solar panels which provides for the spacecraft’s meager power needs.
Its initial design called for small solar panels on both sides of the craft, but one side’s panels were removed to accommodate special mirrors required for laser-range-finding its exact distance from Earth. But now that there is solar power on only one side, sometimes those panels are shadowed by the sails. This leads to brownouts. The team has been able to work around that to some degree, by managing the spacecraft’s power usage and its attitude-control mode. But it’s a good lesson for future solar sail spacecraft.
The LightSail 2 team has also added another mode to the spacecraft that they call the Sun-pointing mode.
The Sun-pointing mode will keep the spacecraft’s solar sail facing the Sun during its entire orbit. This will limit the re-orienting of the spacecraft to reduce the effect of frequent orientation changes that impart problematic momentum to the spacecraft by the momentum wheel. It also helps with battery charging by the solar cells, though it won’t reduce the orbital decay.
The new mode will also help with the spacecraft’s pointing accuracy, and will give it a more consistent starting attitude for on/off thrust maneuvers.
The Planetary Society intends to closely monitor the spacecraft’s orbital decay to see what effect the sails themselves have. This is largely for other teams studying how drag sails can be used to purposefully de-orbit spacecraft.
They’ll also continue to take pictures. The primary reason for the pictures is to monitor the state of the sails, but they’re nice eye candy, too.
You can find out more about LightSail 2 at The Planetary’s Society’s website. They’re a non-profit society, so you can join if you’d like to be a part of their mission. It’s a great way for citizens to contribute.
- Press Release: Here’s What We’ve Learned So Far from LightSail 2
- Full Report: Orbit and Attitude Performance of the LightSail 2 Solar Sail Spacecraft
- The Planetary Society: The Story of LightSail, Part 1 | 0.87621 | 3.712753 |
Researchers at the Worldwide Centre for Radio Astronomy Analysis have uncovered the major explosion at any time noticed in the universe considering that the Major Bang.
The explosion emanated from a supermassive black gap at the heart of the Ophiuchus galaxy cluster some 390 million light-several years from Earth.
“We have viewed outbursts in the centres of galaxies before but this one particular is really, really large,” Melanie Johnston-Hollitt, professor at the Curtin College node of the Worldwide Centre for Radio Astronomy Analysis and co-author of the paper uploaded to preprint archive arXiv earlier this thirty day period, reported in a assertion.
“And we you should not know why it’s so major.”
To make the discovery, the scientists utilized 4 telescopes throughout the globe, which includes NASA’s Chandra X-ray Observatory and the European Area Agency’s XMM-Newton X-ray house observatory.
It was these a violent explosion that it pretty much punched a gap in the plasma surrounding the black gap, as noticed as a result of X-ray telescope observations of the galaxy cluster.
Simona Giacintucci, from the Naval Analysis Laboratory in Washington DC and guide author, as opposed the blast to the 1980 eruption of Mount St. Helens — one particular of the most violent volcanic eruptions in US heritage.
“The big difference is that you could suit 15 Milky Way galaxies in a row into the crater this eruption punched into the cluster’s warm gasoline,” Giacintucci reported in the assertion.
The blast was not only gigantic, but also particularly slow.
“It transpired pretty bit by bit — like an explosion in slow movement that took spot above hundreds of tens of millions of several years,” Johnston-Hollitt discussed.
Scientists at NASA were being ready to validate the unparalleled blast. “The radio facts suit inside the X-rays like a hand in a glove,” co-author Maxim Markevitch from NASA’s Goddard Area Flight Heart reported in the assertion. “This is the clincher that tells us an eruption of unparalleled dimensions happened here.”
The discovery could open up doors for even further discoveries like this one particular.
“It truly is a little bit like archaeology,” Johnston-Hollitt reported. “We have been presented the applications to dig deeper with small frequency radio telescopes so we need to be ready to obtain additional outbursts like this now.”
The group is now searching to make even further observations with twice the quantity of antennas, expanding sensitivity tenfold, according to Johnston-Hollitt.
This report was at first posted by Futurism. Read the authentic report. | 0.824343 | 3.724651 |
What is the form of a planetary orbit? The astronomers from Ptolemy to Copernicus had a clear (but wrong) answer to this question: A planet moves on a circle or at least on an orbit which can be explained by superposition of circular motions. It was Johannes Kepler who finished with this wrong idea in 1609. After he had analysed the large and precise observational data of Tycho Brahe, he found that the planets orbit on ellipses. The points of an ellipse are characterized by the property that the sum of their distances to the so-called foci is constant.
Kepler's first law of undisturbed planetary motion:|
The orbit of each planet is an ellipse and the Sun is at one focus.
The following Java applet illustrates this law. A planet (blue) can be displaced with pressed mouse button on its orbit around the Sun (red). On the top right of the green panel you can select one of the nine planets or Halley's Comet. In addition, it is possible to investigate the orbit of an imaginary celestial body by entering its semimajor axis and numerical eccentrity (less than 1). The program will calculate the length of the semiminor axis and the current, the minimal and the maximal distance from the Sun. These lengths are given in astronomical units (AU). 1 AU = 1.49597870 x 1011 m is defined as the average distance between Earth and Sun. On the bottom right you can decide whether the elliptical orbit, the axes of the ellipse respectively the connecting lines between the celestial body and the foci (F and F') shall be drawn.
© Walter Fendt, March 25, 2000
Last modification: January 18, 2003 | 0.863178 | 3.506196 |
Isn’t it a nice feeling to know you’re surrounded by family, with all the loving support and positive energy necessary to achieve optimal health and success in life? Conversely, aren’t these achievements far more difficult when that support network is removed? Well, like a loving, caring family, our planet possesses a special ability to nurture all life on it. But rather than using encouraging words or children’s aspirin, Mother Earth supports its denizens with resonant frequencies.
I’m referring to the Schumann resonance (SR), which consists of naturally occurring, extremely low frequency (ELF) electromagnetic waves that inhabit the space above the Earth and below the ionosphere. It sounds trippy, but this is a real thing. Discovered—or more accurately, mathematically predicted—by Winfried Otto Schumann in 1952, SR is sustained by the energy created by the 2000 or so thunderstorms that produce about 50 flashes of lightning around the planet every second.
The SR ELF electromagnetic waves encircle the globe, hug-like, with the lowest-frequency mode occurring around 7.83Hz. Higher resonance modes peak every 6.5Hz or so (14.3, 20.8, 27.3 and 33.8, etc, up to about 60Hz), but this article is concerned with that predominant wave of 7.83Hz.
Potential Impact On Human Health
Obviously, our survival is dependent on the Earth’s atmosphere for oxygen and its terrestrial bounty of food and water. But ever more evidence is suggesting that we also require a steady diet of geomagnetic resonances to maintain optimal health, and the Schumann resonance in particular. Upon discovering that the fundamental Schumann frequency of 7.83Hz is very close to that of human alpha wave rhythms, Schumann’s doctoral student Herbert König was one of the first modern researchers to associate SR with human bioactivity.
Centuries before König, though, ancient Indian Rishis also knew about it, enhancing it with the isochronic tonal frequencies of the sound ‘OM’. In fact, plenty of anthropological evidence suggests humans of all cultures have, over the millennia, attempted to achieve trance states by synchronizing with planetary resonances, before even knowing precisely what those were. This was done through various rituals like shamanic drumming and dancing, or religious behaviours such as bobbing and swaying during prayer.
Isochronic tones are regular beats of a single tone used for brainwave training. They differ from monaural beats, which are constant sine wave pulses rather than entirely separate pulses of a single tone. As the contrast between noise and silence is more pronounced than the constant pulses of monaural beats, the stimulus is stronger and has a greater effect on brain entrainment. This frequency has been associated with high levels of hypnotizability and meditation, increased HGH levels, and enhanced cerebral blood flow levels.
Since alpha waves closely resemble the fundamental SR frequency, the thinking is that by intentionally generating them (through the aforementioned methods), the two frequencies combine, thus increasing the strength of our own alpha waves. Shouldn’t this in turn make us feel better and refreshed and in tune with the planet, like a form of environmental synchronization? Indeed, theories abound that since we (indeed, all Earth creatures) evolved in the figurative embrace of SR, somehow we must have incorporated it into our brainwaves, much in the way that animal blood plasma is chemically similar to seawater, since animals evolved in it.
Following from this: If humans are basically in tune with Earth’s natural electromagnetic frequencies, it stands to reason that disruptions of these frequencies may affect human health.
Circadian Rhythms and the Schumann Resonance
Scientist Rütger Wever researched the circadian rhythms of human beings (our ‘internal clock’), and how humans behave when placed in an environment in which they have no external time cues and are free to choose their own sleep/wake and light/dark schedules.
Working with fellow German researcher Jürgen Aschoff, Wever created an underground bunker to use as a laboratory in which human subjects could be shielded from any external time cues, including variations in light, temperature, electromagnetic fields – and the Schumann Resonance. Between 1964 and 1989, this bunker was used to conduct 418 studies on 447 human volunteers.
One of the key findings of these experiments was that when free to self-select their schedules, humans ran on an approximately 25-h day, and chose to go to bed at a much later circadian phase, resulting in a lengthening of the sleep/wake cycle period due to the delaying effects of light exposure at these nighttime circadian phases.
Another seminal finding that came out of the Andechs bunker experiments was the discovery that human sleep/wake cycles could desynchronize from the circadian rhythm of core body temperature, a phenomenon known as ‘Spontaneous Internal Desynchrony‘. Endocrine function, thyroid function, depression and other affective disorders manifested in the bunker subjects. However, when a machine that resonates at 7.83Hz was placed in the bunker, the subjects found that their malaise and illnesses disappeared or were alleviated.
Bees, Pollination, and SR
But humans aren’t the only ones affected by The Schumann Resonance – all animals are, too, including bees. To say that bees are a keystone species feels like a massive understatement. Without bees, the vast majority of food crops wouldn’t get pollinated, and we and every other species that rely on those crops for food, either directly or indirectly, would struggle for survival.
The effects of neonicotinoids and GMO’s on dwindling bee populations are well-documented. Yet there’s also a considered consensus that an overload of electromagnetic frequencies are jamming bees’ internal orientation, navigation and communication systems, for which they rely on the Earth’s natural magnetic field. As a result, bees are simply getting lost, unable to return to the hive, and dying off. Of course, Schumann Resonance signifies the Earth’s natural magnetic field; so in fact, the bees rely on SR for navigation. But all the geomagnetic disturbance or “electro smog” we produce (such as that from wireless technologies like cell phones and Bluetooth) has obscured SR, which may well be impacting the bees’ ability to navigate—to the detriment to all life on the planet.
Scientists also state that animals that migrate, from birds to whales, could be affected by even small changes in the Schumann Resonance.
Many studies have addressed the ideas that disrupting SR may impact human health, starting with L.B. Hainsworth’s pioneering research, which lent credence to previous hypotheses (like König’s) on the human health correlates of SR. Hainsworth recognized that the frequency of the dominant human brainwave rhythm (10.5Hz) and the average frequency at which there is minimal natural interference in the Earth-ionosphere cavity are identical. He understood that this shared frequency makes evolutionary sense, with the human brain operating on a “channel” jammed by minimal “noise.” Assuming our brains are sensitive to Schumann resonance signals, and that these signals have remained at consistent frequencies over evolutionary time, it’s fairly safe to accept the possibility (as Hainsworth and others have) that our central nervous system has evolved to rely on them to synchronize internal biorhythms.
Furthermore, any alteration or occlusion of these signals—as from electro smog—may cause a breakdown or blockage of this synchronization mechanism on which we rely, thus drowning out the health-promoting, possibly formative frequency of SR. Many people believe this is one reason for the putative increase in cancers and other diseases we have experienced over the last half-century. While evidence is growing that mobile phones may cause cancer, further study is required to determine more precise consequences of electro smog on human health.
But research on electromagnetic energy’s effects on human wellness offers more clarity. Since Hainsworth’s work three decades ago, multiple studies (such as this one and this one) have strengthened links between SR and other geomagnetic resonances and human health, cognitive function, emotions, and behavior. Some (e.g.) suggest that any de-synchronizing geomagnetic disruptions can interfere not only with sleep, mental equilibrium, and energy levels but also with brain, cardiovascular and autonomic nervous system function, circadian rhythm, hormonal secretions, and reproduction.
We Are Human Antennas
While the literature highlights these specific effects, the mechanism(s) accounting for how these effects actually occur isn’t fully understood. Theories abound, of course. One suggestion (e.g., here and here) is that extreme swings in solar-geomagnetic activity (as from solar flares or storms) may disrupt the brain’s levels of melatonin, a powerful antioxidant and hormone that plays a significant role in circadian rhythm regulation and immune system function.
Another intriguing possibility (explored here) concerns the ferrous mineral magnetite, which may transduce received magnetic energy into a nervous signal, thus facilitating the ability of electromagnetic radiation to produce biological effects in organisms. Multiple studies (e.g. here and here) have identified magnetite in human and other animal tissues, strengthening this theory.
Whatever the true nature of the relationship between SR and other ELF electromagnetic waves and human health, the best way to enhance our understanding of it may be through the kind of multidisciplinary approach that’s required to study interconnectedness. The study of interconnectivity is still in its infancy, not yet accepted by the mainstream scientific community. But it incorporates such disciplines as geosciences, astrophysics and human and animal studies.
As psychologist and author Louise Samways notes, the human body is like a radio transceiver connected to an aerial—it’s able to transmit and receive energy from the surrounding environment, and one of those radiant energy signals originates from Schumann Resonance, a frequency that evidently impacts our sense of time, bio-cycles, and our health. We should thus try to optimize our exposure to it by minimizing the amount of electro-smog to which we’re exposed.
At least we can rest easier knowing we’re in its warm, supportive embrace. But above all, it’s worth noting that we are connected to this small blue planet in myriad ways we’re only beginning to understand.
By Jody McCutcheon, originally posted on Eluxe Magazine (Partner)
Main image: messagescelestes-archives.ca
- Sun-Safe Must-Dos: Treat Your Skin With Respect Inside and Out - February 22, 2017
- The Schumann Resonance: Feeling The Earth’s Healing Vibrations - December 26, 2016 | 0.830602 | 3.029623 |
The Cat’s Eye Nebula (NGC 6543) is one of the best known planetary nebulae in the sky. Its more familiar outlines are seen in the brighter central region of the nebula in this impressive wide-angle view. But the composite image combines many short and long exposures to also reveal an extremely faint outer halo. At an estimated distance of 3,000 light-years, the faint outer halo is over 5 light-years across. Planetary nebulae have long been appreciated as a final phase in the life of a sun-like star. More recently, some planetary nebulae are found to have halos like this one, likely formed of material shrugged off during earlier episodes in the star’s evolution. While the planetary nebula phase is thought to last for around 10,000 years, astronomers estimate the age of the outer filamentary portions of this halo to be 50,000 to 90,000 years. Visible on the left, some 50 million light-years beyond the watchful planetary nebula, lies spiral galaxy NGC 6552. | 0.824413 | 3.414333 |
Pan and moons like it have profound effects on Saturn’s rings. The effects can range from clearing gaps, to creating new ringlets, to raising vertical waves that rise above and below the ring plane. All of these effects, produced by gravity, are seen in this image from the Cassini probe.
Pan (28 kilometres or 17 miles across), seen in image centre, maintains the Encke Gap in which it orbits, but it also helps create and shape the narrow ringlets that appear in the Encke gap. Two faint ringlets are visible in this image, below and to the right of Pan.
Many moons, Pan included, create waves at distant points in Saturn’s rings where ring particles and the moons have orbital resonances. Many such waves are visible here as narrow groupings of brighter and darker bands. Studying these waves can provide information on local ring conditions.
The view looks toward the unilluminated side of the rings from about 22 degrees below the ring plane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on 3 April 3 2016.
The view was obtained at a distance of approximately 373,000 kilometres (232,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 140 degrees. Image scale is 2 kilometres (1.2 miles) per pixel.
Saturn: Exploring the Ringed Planet
Find out more about Saturn and its moons in this 196-page special edition from Astronomy Now. Order from our online store. | 0.800557 | 3.144284 |
- A baby planet was just spotted by scientists using the Very Large Telescope in Chile.
- The object, a swirling mass of matter surrounding a central point in space, is believed to be the first in-progress planet spotted by scientists.
- As telescope technology improves, our ability to study and understand what is happening in other star systems will grow.
- Visit BGR’s homepage for more stories.
Planets don’t just pop out of nowhere. They can form in different ways but one thing is consistent about all of them: All the matter that makes up a planet was, at some point in the past, drifting free of all the other particles that now surround it.
Now, astronomers using the European Southern Observatory’s Very Large Telescope have spotted what they think is a planet in the midst of being born. A central point in a swirling mass of dust and gas, it may be the first baby planet ever spotted by humans.
As ESO explains in a new blog post, the mass of material was spotted orbiting a young star called AB Aurigae. The planet-in-progress looks like a giant storm in space, but it’s actually a collection of matter slowly coalescing into a solid form. Or, at least that’s what astronomers are hoping for.
“Thousands of exoplanets have been identified so far, but little is known about how they form,” Anthony Boccaletti, lead author of a paper on the discovery published in the journal Astronomy and Astrophysics, said in a statement. “We need to observe very young systems to really capture the moment when planets form.”
The Very Large Telescope may have allowed scientists to see that very thing, though it’s hard to know for sure. Some models of planet formation have hinted at the possibility of twisting, swirling shapes that precede the birth of a baby planet. It makes sense, according to the researchers.
“The twist is expected from some theoretical models of planet formation,” Anne Dutrey, co-author of the work, explains. “It corresponds to the connection of two spirals — one winding inwards of the planet’s orbit, the other expanding outwards — which join at the planet location. They allow gas and dust from the disc to accrete onto the forming planet and make it grow.”
Eventually, all or nearly all of the matter swirling in space around the central point will become part of the new planet. This process is believed to take billions of years, so we’re not likely to catch a glimpse of the final product in our lifetimes. Still, it’s incredible to see it in its current state.
Going forward, the researchers note that the Extremely Large Telescope (don’t you just love these naming conventions?) that is currently in development will offer an even clearer look at exoplanets, and perhaps give us a better idea of exactly what is happening with this particular baby planet. | 0.801426 | 3.512643 |
On June 23, 2013 the full moon will not only be the closest to Earth for the year, but it will also appear the biggest full moon for 2013. It will be 14% bigger and 30% brighter than other full Moons of 2013. It is also known as a supermoon and it will be followed by king tides between June 22 and June 25, 2013.
King tides are also known as perigean spring tides. They are extreme high tide events that occur when the Sun and Moon’s gravitation forces reinforce one another at times of the year when the moon is closest to the Earth. They happen twice a year, but they are typically more dramatic during the winter. When king tides occur during cyclones, floods or storms, water levels can rise to higher levels and have the potential to cause great damage to property and the coastline.
King tides aren't part of climate change; they are a natural part of tidal cycles, no more than the very highest tides that occur at each place. They occur naturally and regularly, they are predictable and expected. King tide occurrences offer us a chance to visualize what normal sea levels may look like in the future.
‘King tide’ is not a scientific term, nor is it used in a scientific context. Use of the term ‘king tide’ originated in Australia, New Zealand and other Pacific nations to refer to an especially high tide that occurs only a few times per year. The King Tides Initiative began in Queensland, Australia in 2009 and was quickly noticed by British Columbia, Washington, California, and Oregon, who each began participating in the following years.
This year's king tides will be especially interesting in Australia. The biggest tide of the Australian summer has sent water flowing over roads and car parks along the Queensland coastline in Jannuary 2013. Watch the video here.
The tidal range varies around the Australian coast. According to Australia Bureau of Statistics (ABS), from the western end of Arnhem Land to the Torres Strait the range is about 3 metes and in Darwin the range can be between 7 and 9 metres. Western Australia has the largest tidal range from almost 11 m in Collier Bay to less than a metre at Geraldton! The southern coast has a small range of around 1 to 1.5m and Tasmania's tidal range varies between 1 and 3m.
King tides around Western Australia coast began on March 30, 2013 (from the north coast) and is moving along the coast to end on the south coast around June 24, 2013. The next king tide cycle will occurr on July 21, 2013 and will last for about three days.
The moon is the primary source of the gravitational forces which cause the tides. The proximity of the moon to the earth affects the magnitude of a tide at any given time. In each of its 28-day elliptical orbits, the moon reaches a "perigee," which is the closest point of its elliptical orbit to the earth. There will be a slight increase in the range of tides at the perigee of the moon’s orbit, when the moon is closest to the earth. Increases in the range of the tides is seen by a higher than average high tide and a lower than average low tide. In addition, twice each month (around the new moon and full moon), when the sun, earth, and moon are nearly in line, there is an increase in the tidal range. Such tides are called "spring tides." When the occurrence of a new or full moon coincides with the "perigee" of the moon, it’s termed the "perigean spring tides".
Featured image: Full moon over sea (Credit: Belle) | 0.824791 | 3.197192 |
About This Chapter
ILTS Environmental Science: Objects in the Universe - Chapter Summary
This chapter's lessons examine the objects in the universe, both within and outside of our solar system. You will get an overview of how objects in the solar system move and relate to each other, as well as a look at structures farther away. Other lessons cover the origins of the universe itself and the development of objects, including the moon. The videos cover these topics that will prepare you for the exam questions:
- Structure of the sun and its life cycle
- Life cycle of black holes
- Characteristics of asteroids, meteorites and comets
- Radio, reflecting and refracting telescopes
- The big bang theory
- Star formation
- Dwarf planets
- Predictors of life on other planets
You'll be taught by experienced instructors who know how to make learning fun while giving you the knowledge you need. At the end of this chapter, you will be prepared for exam questions on the universe and its objects.
Objectives of the ILTS Environmental Science: Objects in the Universe Course
Illinois requires that individuals who want to teach environmental science at the secondary school level pass the Illinois Licensure Testing System (ILTS) environmental science content area exam. With 125 multiple-choice questions, this exam is divided into six subareas. The questions on the objects of the universe and their dynamic interactions are part of subarea IV. You can prepare for the ILTS exam by taking the self-assessment quizzes found at the end of each video lesson. The quizzes will allow you to become familiar with the format and also assess your knowledge of the subject.
1. Structure of the Sun
Discover the layers of the sun, including the core, radiative zone, convective zone, photosphere, chromosphere, and corona. Find out which layers you can see from Earth. Investigate what sunspots and solar flares are.
2. Life Cycle of Black Holes
Learn about black holes, their myths and their reality. Learn how black holes form after stars undergo supernovae and create singularities. Discover how big black holes grow, how scientists find black holes and where black holes are located in the universe.
3. Asteroids, Meteorites & Comets: Definitions and Characteristics
This lesson will cover the definitions and characteristics of asteroids, comets and meteorites. It will also explore what impact they have had on Earth and the impact they might have in the future.
4. Types of Telescopes: Radio, Reflecting & Refracting Telescopes
Learn about the different types of telescopes that astronomers use: X-ray, radio, gamma ray, reflecting and refracting. Learn what the differences are between them and what different things they show us about the universe.
5. Evidence for the Big Bang Theory: Background Radiation, Red-Shift and Expansion
Discover what evidence exists to support the Big Bang theory of the birth of the universe. Learn how cosmic background radiation, the red shift of light and the ongoing expansion of the universe led scientists to believe that the universe was started with the Big Bang.
6. Formation of the Moon: Theories
Explore the four major theories on the formation of the Moon. The theories include the fission theory, capture theory, condensation theory and giant impact theory. Also look at both information supporting and flaws found in these theories.
7. Planetary Predictors of Extraterrestrial Life
Investigate what is needed for life to exist anywhere and the implications for life in our solar system beyond Earth. Consider Mars and some of the moons of Jupiter and Saturn, including Europa, Callisto, Ganymede and Enceladus.
8. Outer Planets of the Solar System: Jupiter, Saturn, Uranus, Neptune
Take a tour of the outer planets of our solar system: Jupiter, Saturn, Uranus, and Neptune. Find out what makes each of these gas giants unique and learn about Pluto, a dwarf planet.
9. Star Formation: Main Sequence, Dwarf & Giant Stars
Learn how stars are born, beginning with a protostar. Then learn about stars in later stages of life, including main sequence stars, brown dwarfs, red giants, and black holes.
10. Dwarf Planets of the Solar System: Pluto, Eris, Haumea & Ceres
Discover why Pluto had to leave the league of planets and was downgraded to a dwarf planet. Learn the definitions for planet and dwarf planet. Find out about the currently classified dwarf planets in our solar system: Pluto, Eris, Ceres, Haumea and Makemake.
11. Formation of the Earth: Theories
In this lesson, the theory of how the planet Earth formed will be discussed. This includes looking at how it differentiated into three layers, how it formed its atmosphere, water, and land features, and how it continues to evolve today.
12. Inner Planets of the Solar System: Mercury, Venus, Earth & Mars
Take a tour of the four inner planets: Mercury, Venus, Earth and Mars. Known as the terrestrial planets, find out what makes each of them unique and how they are different from the outer planets, the gas giants.
13. Stages of the Sun's Life Cycle
Discover our sun, the provider of energy for life on Earth. Learn how the sun was born, how it lives as a main sequence star, how it will age into a red giant and how it will die as a white dwarf.
14. Galaxy Formation: Spiral, Elliptical & Irregular Galaxies
This lesson explains how galaxies form, starting with the Big Bang. You'll also learn about the solar nebula hypothesis and three galaxy types, including spiral, elliptical, and irregular galaxies.
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Other chapters within the ILTS Science - Environmental Science (112): Test Practice and Study Guide course
- ILTS Environmental Science: Accepted Practices of Science
- ILTS Environmental Science: Cell Structure and Function
- ILTS Environmental Science: Principles of Heredity and Biological Evolution
- ILTS Environmental Science: Systems of the Body
- ILTS Environmental Science: Characteristics and Life Functions of Organisms
- ILTS Environmental Science: Climate Change and Cycles
- ILTS Environmental Science: Organisms in the Environment
- ILTS Environmental Science: Nature and Properties of Energy
- ILTS Environmental Science: Structure and Properties of Matter
- ILTS Environmental Science: Forces and Motion
- ILTS Environmental Science: Magnetism
- ILTS Environmental Science: Waves and Electromagnetic Spectrum
- ILTS Environmental Science: Electricity Fundamentals
- ILTS Environmental Science: Land, Water, and Atmospheric Systems
- ILTS Environmental Science: The Dynamic Nature of Earth
- ILTS Environmental Science: Origins and Changes in the Universe
- ILTS Environmental Science: Energy Flow in Natural Ecosystems
- ILTS Environmental Science: How Humans Affect the Global Environment
- ILTS Environmental Science: Understanding National and Global Environmental Policy
- ILTS Environmental Science: Illinois, United States and World Environmental History
- ILTS Science - Environmental Science Flashcards | 0.81253 | 3.297814 |
Convert 422 Years to Hours
To calculate 422 Years to the corresponding value in Hours, multiply the quantity in Years by 8760 (conversion factor). In this case we should multiply 422 Years by 8760 to get the equivalent result in Hours:
422 Years x 8760 = 3696720 Hours
422 Years is equivalent to 3696720 Hours.
How to convert from Years to Hours
The conversion factor from Years to Hours is 8760. To find out how many Years in Hours, multiply by the conversion factor or use the Time converter above. Four hundred twenty-two Years is equivalent to three million six hundred ninety-six thousand seven hundred twenty Hours.
Definition of Year
A year (symbol: y; also abbreviated yr.) is the orbital period of the Earth moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by changes in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the globe, four seasons are generally recognized: spring, summer, autumn and winter. In tropical and subtropical regions several geographical sectors do not present defined seasons; but in the seasonal tropics, the annual wet and dry seasons are recognized and tracked. A calendar year is an approximation of the number of days of the Earth's orbital period as counted in a given calendar. The Gregorian, or modern, calendar, presents its calendar year to be either a common year of 365 days or a leap year of 366 days.
Definition of Hour
An hour (symbol: h; also abbreviated hr.) is a unit of time conventionally reckoned as 1⁄24 of a day and scientifically reckoned as 3,599–3,601 seconds, depending on conditions. The seasonal, temporal, or unequal hour was established in the ancient Near East as 1⁄12 of the night or daytime. Such hours varied by season, latitude, and weather. It was subsequently divided into 60 minutes, each of 60 seconds. Its East Asian equivalent was the shi, which was 1⁄12 of the apparent solar day; a similar system was eventually developed in Europe which measured its equal or equinoctial hour as 1⁄24 of such days measured from noon to noon. The minor variations of this unit were eventually smoothed by making it 1⁄24 of the mean solar day, based on the measure of the sun's transit along the celestial equator rather than along the ecliptic. This was finally abandoned due to the minor slowing caused by the Earth's tidal deceleration by the Moon. In the modern metric system, hours are an accepted unit of time equal to 3,600 seconds but an hour of Coordinated Universal Time (UTC) may incorporate a positive or negative leap second, making it last 3,599 or 3,601 seconds, in order to keep it within 0.9 seconds of universal time, which is based on measurements of the mean solar day at 0° longitude.
Using the Years to Hours converter you can get answers to questions like the following:
- How many Hours are in 422 Years?
- 422 Years is equal to how many Hours?
- How to convert 422 Years to Hours?
- How many is 422 Years in Hours?
- What is 422 Years in Hours?
- How much is 422 Years in Hours?
- How many hr are in 422 yr?
- 422 yr is equal to how many hr?
- How to convert 422 yr to hr?
- How many is 422 yr in hr?
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- How much is 422 yr in hr? | 0.828035 | 3.214714 |
Lysithea is another small and poorly known satellite. Lysithea was named for a daughter of Oceanus who was one of Zeus's lovers. Although Lysithea is very small, with a radius of only 11 miles (18 km), it was discovered in 1938, before the more precise techniques of modern astronomy were developed.
Beyond Lysithea are Elara and S/2000 J11, both members of the Himalia prograde irregular group. Outside the Himalia group, the remainder of Jupiter's moons are small, poorly known captured asteroids that orbit in a retrograde sense. The Ananke retrograde group has orbits at 145 to 150 degrees to Jupiter's equatorial plane, and the more distant moons have orbits that are that steep or even steeper.
Jupiter has by far the largest known population of moons of any planet in the solar system, almost twice the number of moons of the second contender, Saturn. No doubt a great many additional moons will be added to Jupiter's list over the coming decade, but it is almost a certainty that all will be small captured asteroids with highly inclined and elliptical orbits, a sort of solar system remainder swarm attracted to the giant gravity well of Jupiter. Jupiter's large satellites, including Ganymede, the largest moon in the solar system, display a mind-boggling variety of compositions, appearances, and behaviors, creating a compelling natural laboratory for the study of planetary evolution. The icy Europa and its near neighbor Io form one of the great contrasts in planetary science: They each have new surfaces, caused in Europa's case by floods of ice from its watery interior, and in Io's by floods of unusually hot magma.While Europa is a candidate location for the development of life, Io is an inhospitable place, covered with sulfur, bombarded by Jupiter's magnetic field, and continuously re-covered by magma in volumes far greater than are produced on Earth each year. These moons will no doubt be the targets of future space missions.
Was this article helpful? | 0.873171 | 3.402568 |
Zeta Ophiuchi -- Runaway Star Plowing through Space Dust
The blue star near the center of this image is Zeta Ophiuchi. When seen in visible light it appears as a relatively dim red star surrounded by other dim stars and no dust. However, in this infrared image taken with NASA's Wide-field Infrared Survey Explorer, or WISE, a completely different view emerges. Zeta Ophiuchi is actually a very massive, hot, bright blue star plowing its way through a large cloud of interstellar dust and gas.
Astronomers theorize that this stellar juggernaut was likely once part of a binary star system with an even more massive partner. It's believed that when the partner exploded as a supernova, blasting away most of its mass, Zeta Ophiuchi was suddenly freed from its partner's pull and shot away like a bullet moving 24 kilometers per second (54,000 miles per hour). Zeta Ophiuchi is about 20 times more massive and 65,000 times more luminous than the sun. If it weren't surrounded by so much dust, it would be one of the brightest stars in the sky and appear blue to the eye. Like all stars with this kind of extreme mass and power, it subscribes to the 'live fast, die young' motto. It's already about halfway through its very short 8-million-year lifespan. In comparison, the sun is roughly halfway through its 10-billion-year lifespan. While the sun will eventually become a quiet white dwarf, Zeta Ophiuchi, like its ex-partner, will ultimately die in a massive explosion called a supernova.
Perhaps the most interesting features in this image are related to the interstellar gas and dust that surrounds Zeta Ophiuchi. Off to the sides of the image and in the background are relatively calm clouds of dust, appearing green and wispy, slightly reminiscent of the northern lights. Near Zeta Ophiuchi, these clouds look quite different. The cloud in all directions around the star is brighter and redder, because the extreme amounts of ultraviolet radiation emitted by the star are heating the cloud, causing it to glow more brightly in the infrared than usual.
Even more striking, however, is the bright yellow curved feature directly above Zeta Ophiuchi. This is a magnificent example of a bow shock. In this image, the runaway star is flying from the lower right towards the upper left. As it does so, its very powerful stellar wind is pushing the gas and dust out of its way (the stellar wind extends far beyond the visible portion of the star, creating an invisible 'bubble' all around it). And directly in front of the star's path the wind is compressing the gas together so much that it is glowing extremely brightly (in the infrared), creating a bow shock. It is akin to the effect you might see when a boat pushes a wave in front it as it moves through the water. This feature is completely hidden in visible light. Infrared images like this one from WISE shed an entirely new light on the region.
The colors used in this image represent specific wavelengths of infrared light. Blue and cyan (blue-green) represent light emitted at wavelengths of 3.4 and 4.6 microns, which is predominantly from stars. Green and red represent light from 12 and 22 microns, respectively, which is mostly emitted by dust.
Massive Star Makes Waves
The giant star Zeta Ophiuchi is having a "shocking" effect on the surrounding dust clouds in this infrared image from NASA's Spitzer Space Telescope. Stellar winds flowing out from this fast-moving star are making ripples in the dust as it approaches, creating a bow shock seen as glowing gossamer threads, which, for this star, are only seen in infrared light.
Zeta Ophiuchi is a young, large and hot star located around 370 light-years away. It dwarfs our own sun in many ways -- it is about six times hotter, eight times wider, 20 times more massive, and about 80,000 times as bright. Even at its great distance, it would be one of the brightest stars in the sky were it not largely obscured by foreground dust clouds.
This massive star is travelling at a snappy pace of about 54,000 mph (24 kilometers per second), fast enough to break the sound barrier in the surrounding interstellar material. Because of this motion, it creates a spectacular bow shock ahead of its direction of travel (to the left). The structure is analogous to the ripples that precede the bow of a ship as it moves through the water, or the sonic boom of an airplane hitting supersonic speeds.
The fine filaments of dust surrounding the star glow primarily at shorter infrared wavelengths, rendered here in green. The area of the shock pops out dramatically at longer infrared wavelengths, creating the red highlights.
A bright bow shock like this would normally be seen in visible light as well, but because it is hidden behind a curtain of dust, only the longer infrared wavelengths of light seen by Spitzer can reach us.
Bow shocks are commonly seen when two different regions of gas and dust slam into one another. Zeta Ophiuchi, like other massive stars, generates a strong wind of hot gas particles flowing out from its surface. This expanding wind collides with the tenuous clouds of interstellar gas and dust about half a light-year away from the star, which is almost 800 times the distance from the sun to Pluto. The speed of the winds added to the star's supersonic motion result in the spectacular collision seen here.
Our own sun has significantly weaker solar winds and is passing much more slowly through our galactic neighborhood so it may not have a bow shock at all. NASA's twin Voyager spacecraft are headed away from the solar system and are currently about three times farther out than Pluto. They will likely pass beyond the influence of the sun into interstellar space in the next few years, though this is a much gentler transition than that seen around Zeta Ophiuchi.
For this Spitzer image, infrared light at wavelengths of 3.6 and 4.5 microns is rendered in blue, 8.0 microns in green, and 24 microns in red.
JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. | 0.92044 | 3.862684 |
Magnetic Wormhole Demonstrated for First Time
Magnetic Wormhole Demonstrated For First Time—-Ever
Could we be a step closer to the future of interstellar space travel?
Physicists at the Autonomous University of Barcelona (Universitat Autònoma de Barcelona) have demonstrated for the first time a wormhole allowing two regions of space to be connected magnetically. The study, published in Nature revealed that the experiment was conducted using two magnetic monopoles, which aren’t observably evident in nature. The poles created a sort of ‘warp’ in which an object appeared to traverse space outside of the normal three dimensional realms into what can only be described as a fourth dimension. Researchers used a tri-layer model to sandwich superconducting material between two sheets of ferromagentic material in the shape of a sphere to create the wormhole. According to one researcher, the device “changes the topology of space, as if the inner region has been magnetically erased from space.”
Unlike prior models implemented by the team in 2014, this wormhole’s magnetic field cannot be detected by diagnostic devices. Speculative applications for this model outside of gravitational applications in interstellar space travel could be applied in the future of magnetic resonance imaging in medicine, improving efficiency of MRI’s and even perhaps allow for remote body scans of patients.
According to the study’s abstract:
“Wormholes are fascinating cosmological objects that can connect two distant regions of the universe. Because of their intriguing nature, constructing a wormhole in a lab seems a formidable task. A theoretical proposal by Greenleafet al. presented a strategy to build a wormhole for electromagnetic waves. Based on metamaterials, it could allow electromagnetic wave propagation between two points in space through an invisible tunnel. However, an actual realization has not been possible until now. Here we construct and experimentally demonstrate a magnetostatic wormhole. Using magnetic metamaterials and metasurfaces, our wormhole transfers the magnetic field from one point in space to another through a path that is magnetically undetectable. We experimentally show that the magnetic field from a source at one end of the wormhole appears at the other end as an isolated magnetic monopolar field, creating the illusion of a magnetic field propagating through a tunnel outside the 3D space.”
This new breakthrough, combined with news this week about recent efforts to define the possibility that objects could pass through a black hole and survive as well as attempts to view the black hole in the center of our galaxy make for exciting future possibilities.
What do you think of these new breakthroughs in physics? What other practical applications might this be used for in the future? Join us in the discussion! Comment, Share on Facebook and join us on Twitter, hashtag, #DMTalk! | 0.84518 | 3.65805 |
The diversity of galaxies in the early universe was as varied as the many galaxy types seen today, a massive Hubble Space Telescope photos survey reveals.
The Hubble photo survey found that the assorted range of galaxy types seen today were also present about 11 billion years ago, meaning that the types of galaxies seen today, which astronomers described as a "cosmic zoo," have been around for at least 80 percent of the universe’s lifespan. The universe is estimated to be 13.82 billion years old.
At the heart of the new study is a galaxy classification system known as the Hubble Sequence. The research team found that this system still applied to galaxies 11 billion years ago. The research will appear upcoming edition of the Astrophysical Journal [See Hubble's Photos of Galaxies from 11 Billion Years Ago]
"This is a key question: when and over what timescale did the Hubble Sequence form?" study lead author BoMee Lee of the University of Massachusetts, said in a statement. "To do this you need to peer at distant galaxies and compare them to their closer relatives, to see if they too can be described in the same way."
The new study is part of the Hubble Space Telescope Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey, or CANDLES.
"The largest project in the history of Hubble, it aims to explore galactic evolution in the early universe and the very first seeds of cosmic stracture at less than 1 billion years after the Big Bang," Hubble officials said in a statement.
The Hubble Sequence divides galaxies into three types based on their appearance. Spiral galaxies in the prime of their lives are full of gas used in star formation. Once that gas runs out, they can transition into a somewhat blob-like elliptical galaxy.
A third type of galaxy in the sequence, known as a lenticular galaxy, represents a transitional phase between a middle aged spiral galaxy and an older elliptical galaxy. These kinds of galaxies have a bright bulge like an elliptical galaxy; yet maintain some spiral-like structure as their star-forming gas runs out.
Scientists observed these kinds of galaxies in the early universe.
"This is the only comprehensive study to date of the visual appearance of the large, massive galaxies that existed so far back in time," co-author Arjen van der Wel of the Max Planck Institute for Astronomy in Heidelberg, Germany said in a statement. "The galaxies look remarkably mature, which is not predicted by galaxy formation models to be the case that early on in the history of the universe."
"The Hubble Sequence underpins a lot of what we know about how galaxies form and evolve — finding it to be in place this far back is a significant discovery," Lee said. | 0.858959 | 4.014801 |
Which planet would you say is closest to Earth? Is it Venus? Mars? If you’re anything like me, you would have answered Mars. After all, it’s where space agencies want to send the first manned mission to another planet — surely they would just choose the closest. Wouldn’t they?
In a recent episode of the BBC’s ever-interesting programme More or Less, they tackled this very question. Loyal listener Graham Sherman said that on the BBC Four TV programme The Sky at Night Chris Lintott, professor of astrophysics at Oxford University, said our nearest neighbour was Mars. But Sherman wasn’t so sure. And so the BBC’s Tim Harford put the question to David A. Rothery, professor of planetary geosciences at the Open University: which planet is closest to Earth?
It turns out that the answer depends on when you ask it.
Although the elliptical orbit of Venus is closest to Earth’s own, that doesn’t mean that Venus itself is always the closest planet to us. Sometimes it is, sometimes it isn’t. Each planet takes a different length of time to orbit the Sun1 and so sometimes Mars is quite close to us while Venus is far away, on the other side of the Sun.
Oliver Hawkins, formerly a More or Less researcher and now a data scientist at the House of Commons Library, wrote some code for the programme to calculate which planet was closest to Earth every day for the past fifty years. More or Less then asked Professor Rothery to use the calculations to find out, finally, which planet is closest to Earth. The answer? Mercury.
Yep, Mercury. Or at least, it’s the closest on average. Venus may come closer to Earth than any other planet, but according to Professor Rothery over the last fifty years Mercury has been our closest neighbour 46% of the time, Venus 36% of the time, and Mars 18% of the time.
Apparently, this calculation had never been done before. The data was all available, but no one had thought to check. Unfortunately, More or Less didn’t publish their code — or, more interestingly, their charts — but I really wanted to see what the data looked like. So I worked out how to reproduce it.
Thanks to the hard work of other people, it turned out to be relatively easy. The Jet Propulsion Laboratory, a NASA R&D centre, has published ephemerides — calculated positions of the planets (and other celestial objects) at regular intervals — and Brandon Rhodes has made those calculations easily available in Python via the
jplephem and Skyfield packages. A little while after I’d discovered that, I had a Python script to calculate the planetary distances2 for every day between 1950 and 2050 and then dump them to a CSV. And shortly after that, I had an R script to make the charts you see on this page. I’ve published the code on GitHub.
So, I hear you ask, which planet will be our nearest neighbour over the coming months and years?
- Venus, until 24 February 2019
- Mercury, until 20th December 2019
- Venus, until 7th February 2020
- Mercury, until 16th of March 2020
- Venus, until 4th of August 2020
- Mars, until 20th January 2021
In January 2022 we’ll come as close as we ever do to another planet, when we’ll be about 40 million kilometres from Venus. A few years later, in January 2026, we’ll be far from anything else, 214 million kilometres from our then-nearest neighbour, Mercury. All while we travel at 100,000 kph. Yes, these numbers are staggering. I try not to think about it.
Near the end of the programme, Oxford University’s Professor Lintott told Harford that ‘calculating which planet is closest when is a fun problem’. Indeed it is.
Update, 11 February 2019
Oliver Hawkins, who made the charts mentioned in the programme, wrote about the process he used on his blog. | 0.891792 | 3.494165 |
Video Close-up footage of asteroid Ryugu, taken by the Hayabusa 2 spacecraft as it touched down to retrieve a sample, reveals the near-Earth object’s surface may have been torched by the Sun as its orbit changed over time.
Ryugu, shaped like a spinning-top, circles our star once every 16 months and hangs out between Earth and Mars. Its orbit may not have been so stable in the past, though, according to this here study published today in Science. Images show strips of its surface appeared redder than other sections, suggesting those areas were once exposed to solar heating or space weathering.
"We suggest that a surface reddening event within a short period of time could be explained if Ryugu underwent a temporary orbital excursion near the Sun, causing higher surface heating,” noted the large international team of boffins, led by the University of Tokyo, who worked on the study.
It appears the asteroid should be blue-tinged overall, however, the solar heating and space weathering turned it red – apart from its poles, which received less heating and stayed blue. The academics believe that over time, a constant bombardment by space debris caused the red surface material to mix with the blue stuff underneath to form colored bands across the rock, as illustrated below:
The eggheads also emitted a high-def video of Hayabusa 2 descending on Ryugu last year: the probe touched down on the surface, "sampling horn" first, and fired a small bullet-like projectile to kick up some dust. That material was collected by the horn, and will be returned to Earth. We've shared a slightly lower-res version here:
Launched in 2014, Hayabusa 2 carried multiple instruments, and deployed four rovers on Ryugu when it eventually reached the cosmic boulder. It is expected to return its asteroid samples to Earth in December. Scientists expect the dust particles will be made up of a mixture of the red and blue material. They will analyze it in more detail, looking for more evidence it was scorched by the Sun.
“We predict that the returned sample will contain a mix of altered and unaltered materials, with the former recording a solar heating event,” the team concluded. ® | 0.891449 | 3.738309 |
ESO observations indicate the Neptune-like exoplanet is evaporating
Researchers using ESO’s Very Large Telescope have, for the first time, found evidence of a giant planet associated with a white dwarf star. The planet orbits the hot white dwarf, the remnant of a Sun-like star, at close range, causing its atmosphere to be stripped away and form a disc of gas around the star. This unique system hints at what our own Solar System might look like in the distant future.
“It was one of those chance discoveries,” says researcher Boris Gänsicke, from the University of Warwick in the UK, who led the study, published today in Nature. The team had inspected around 7000 white dwarfs observed by theSloan Digital Sky Survey and found one to be unlike any other. By analysing subtle variations in the light from the star, they found traces of chemical elements in amounts that scientists had never before observed at a white dwarf. “We knew that there had to be something exceptional going on in this system, and speculated that it may be related to some type of planetary remnant.”
To get a better idea of the properties of this unusual star, named WDJ0914+1914, the team analysed it with the X-shooter instrument on ESO’s Very Large Telescope in the Chilean Atacama Desert. These follow-up observations confirmed the presence of hydrogen, oxygen and sulphur associated with the white dwarf. By studying the fine details in the spectra taken by ESO’s X-shooter, the team discovered that these elements were in a disc of gas swirling into the white dwarf, and not coming from the star itself.
“It took a few weeks of very hard thinking to figure out that the only way to make such a disc is the evaporation of a giant planet,” says Matthias Schreiber from the University of Valparaiso in Chile, who computed the past and future evolution of this system.
The detected amounts of hydrogen, oxygen and sulphur are similar to those found in the deep atmospheric layers of icy, giant planets like Neptune and Uranus. If such a planet were orbiting close to a hot white dwarf, the extreme ultraviolet radiation from the star would strip away its outer layers and some of this stripped gas would swirl into a disc, itself accreting onto the white dwarf. This is what scientists think they are seeing around WDJ0914+1914: the first evaporating planet orbiting a white dwarf.
Combining observational data with theoretical models, the team of astronomers from the UK, Chile and Germany were able to paint a clearer image of this unique system. The white dwarf is small and, at a blistering 28 000 degrees Celsius (five times the Sun's temperature), extremely hot. By contrast, the planet is icy and large—at least twice as large as the star. Since it orbits the hot white dwarf at close range, making its way around it in just 10 days, the high-energy photons from the star are gradually blowing away the planet's atmosphere. Most of the gas escapes, but some is pulled into a disc swirling into the star at a rate of 3000 tonnes per second. It is this disc that makes the otherwise hidden Neptune-like planet visible.
“This is the first time we can measure the amounts of gases like oxygen and sulphur in the disc, which provides clues to the composition of exoplanet atmospheres,” says Odette Toloza from the University of Warwick, who developed a model for the disc of gas surrounding the white dwarf.
“The discovery also opens up a new window into the final fate of planetary systems,” adds Gänsicke.
Stars like our Sun burn hydrogen in their cores for most of their lives. Once they run out of this fuel, they puff up into red giants, becoming hundreds of times larger and engulfing nearby planets. In the case of the Solar System, this will include Mercury, Venus, and even Earth, which will all be consumed by the red-giant Sun in about 5 billion years. Eventually, Sun-like stars lose their outer layers, leaving behind only a burnt-out core, a white dwarf. Such stellar remnants can still host planets, and many of these star systems are thought to exist in our galaxy. However, until now, scientists had never found evidence of a surviving giant planet around a white dwarf. The detection of an exoplanet in orbit around WDJ0914+1914, located about 1500 light years away in the constellation of Cancer, may be the first of many orbiting such stars.
According to the researchers, the exoplanet now found with the help of ESO’s X-shooter orbits the white dwarf at a distance of only 10 million kilometres, or 15 times the solar radius, which would have been deep inside the red giant. The unusual position of the planet implies that at some point after the host star became a white dwarf, the planet moved closer to it. The astronomers believe that this new orbit could be the result of gravitational interactions with other planets in the system, meaning that more than one planet may have survived its host star’s violent transition.
“Until recently, very few astronomers paused to ponder the fate of planets orbiting dying stars. This discovery of a planet orbiting closely around a burnt-out stellar core forcefully demonstrates that the Universe is time and again challenging our minds to step beyond our established ideas,” concludes Gänsicke.
Location of WDJ0914+1914 in the constellation of Cancer
This chart shows the location of WDJ0914+1914 in the constellation of Cancer (The Crab). This map shows most of the stars visible to the unaided eye under good conditions, and WDJ0914+1914 itself is highlighted with a red circle on the image. This white dwarf is orbited by a Neptune-like exoplanet that is evaporating, the first ever giant planet found around a white dwarf. | 0.937256 | 3.914075 |
Friends, take out your mobiles in the name of science! Astronomers from the Harvard-Smithsonian Center for Astrophysics are trying to look for fast radio bursts in the Milky Way galaxy with “low-cost radio receivers.” And by that, they mean, your smartphones.
Galactic fast radio bursts (FRBs) have left astronomers scratching their heads. The high-energy radio flashes last about a millisecond and have only been spotted in distant galaxies, making them difficult to study with radio telescopes.
Researchers hoping to understand the origin of these radio flares are looking closer to home. Professors Dan Maoz and Avi Loeb, from Tel Aviv University and Harvard University, believe an active FRB might be right under our noses.
“If fast radio bursts originate from galaxies at cosmological distances, then their all-sky rate implies that the Milky Way may host an FRB on average once every 30 to 1,500 years. If many FRBs persistently repeat for decades or for centuries, a local giant FRB could even be active now,” Maoz and Loeb wrote in a paper accepted for the Monthly Notices of the Royal Astronomical Society.
Its signal would be approximately 1GHz and would have a flux density of 3 × 1010 Jansky – large enough to be detected by mobile phones, Wi‑Fi or GPS. The idea is to create a “Citizens-Science” app that would continuously listen for and record radio signals. Sound files would be periodically uploaded to a website, where all the data can be correlated to identify the position of possible FRBs.
“An FRB in the Milky Way, essentially in our own back yard, would wash over the entire planet at once. If thousands of cell phones picked up a radio blip at nearly the same time, that would be a good sign that we’ve found a real event," said Dan Maoz, lead author of the study.
“[Since] the size of the Milky Way is a million times smaller than the size of the Universe, a local [FRB] event would be a trillion times brighter than the most distant events. Because an FRB from the Milky Way should be so much brighter, it can be detected with a cell phone or a small electronic device that costs tens of dollars instead of a giant radio dish,” Loeb told The Register.
Another option is to employ a network of software defined radio (SDR) kits – popular among radio tinkerers – that can be purchased for as little as $10. The devices can be plugged into the USB port of a laptop or desktop, and data can be uploaded to a website.
But it may not be as straightforward as that, the researchers admitted. Cell phones and SDRs will also detect random noises that could potentially swamp the FRB signals. Little is known about these galactic flares, and if they aren’t repeated then nobody can say how common the events might be.
“A reasonable expectation is then that FRB numbers increase at decreasing luminosities. If so, lower-luminosity FRBs should be detected more frequently by the global cellular network,” the paper said.
“FRBs are extremely bright and their nature is not understood. They require coherent emission by many electrons, of the type that you get in a radio antenna or a laser,” Loeb explained.
He also said their origin was “so puzzling” that it led him to write a paper that examined if the blazes could be linked to “advanced civilizations” living far away in the cosmos. ® | 0.845904 | 3.525668 |
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In theory, two black holes orbiting each other can loose orbital energy, get closer together and eventually merge into one. It will not create any explosion but will send out a massive gravity wave across the Universe. As of June 2016, two have been discovered via Gravity Wave detectors.
Most black holes form from super-massive stars that explode (supernova) at the final stage of their lives. The outer layers explode out while the inner core compresses under gravity. As matter becomes denser, the gravitational force becomes stronger and so compresses the matter further and so on. If the density becomes high enough, then not even light travelling at 300,000km/s cannot escape. The object itself as well as a surrounding area is completely void of light - A Black Hole.
How can they be detected if space is dark too? One method is to observe light being curved around the black hole. A prediction by Einstein is that gravity will bend light around the object. In 1919, stars were photographed near the sun during a total solar eclipse. As Einstein predicted, the stars have 'moved' slightly from their normal positions due to the Sun's gravity bending their light around the sun itself. The stars haven't moved, only their images have. A black hole will distort the light even more. | 0.900268 | 3.105842 |
This has nothing to do with the Veil War, but I found it interesting. A while back, some researchers claimed that they had evidence that a comet had hit North America around 11,000 BC. Most scientists poo-pooed the idea, and went about securing government grants like good scientists.
Undeterred, the researchers went out and found more evidence.
Albert Goodyear, an archaeologist in USC’s College of Arts and Sciences, is a co-author on the study that upholds a 2007 PNAS study by Richard Firestone, a staff scientist at the Department of Energy’s Lawrence Berkeley National Laboratory.
Firestone found concentrations of spherules (micro-sized balls) of metals and nano-sized diamonds in a layer of sediment dating 12,900 years ago at 10 of 12 archaeological sites that his team examined. The mix of particles is thought to be the result of an extraterrestrial object, such as a comet or meteorite, exploding in the earth’s atmosphere. Among the sites examined was USC’s Topper, one of the most pristine U.S. sites for research on Clovis, one of the earliest ancient peoples.
“This independent study is yet another example of how the Topper site with its various interdisciplinary studies has connected ancient human archaeology with significant studies of the Pleistocene,” said Goodyear, who began excavating Clovis artifacts in 1984 at the Topper site in Allendale, S.C. “It’s both exciting and gratifying.”
Younger-Dryas is what scientists refer to as the period of extreme cooling that began around 12,900 years ago and lasted 1,300 years. While that brief ice age has been well-documented – occurring during a period of progressive solar warming after the last ice age – the reasons for it have long remained unclear. The extreme rapid cooling that took place can be likened to the 2004 sci-fi blockbuster movie “The Day After Tomorrow.”
Firestone’s team presented a provocative theory: that a major impact event – perhaps a comet – was the catalyst. His copious sampling and detailed analysis of sediments at a layer in the earth dated to 12,900 years ago, also called the Younger-Dryas Boundary (YDB), provided evidence of micro-particles, such as iron, silica, iridium and nano-diamonds. The particles are believed to be consistent with a massive impact that could have killed off the Clovis people and the large North American animals of the day. Thirty-six species, including the mastodon, mammoth and saber-toothed tiger, went extinct.
Then here’s a funny quote:
The scientific community is rarely quick to accept new theories.
And why might that be?
a 2009 study led by University of Wyoming researcher Todd Surovell failed to replicate Firestone’s findings at seven Clovis sites, slowing interest and research progress to a glacial pace. This new PNAS study refutes Surovell’s findings with its lack of reported evidence.
“Surovell’s work was in vain because he didn’t replicate the protocol. We missed it too at first. It seems easy, but unless you follow the protocol rigorously, you will fail to detect these spherules. There are so many factors that can disrupt the process. Where Surovell found no spherules, we found hundreds to thousands,” said Malcolm LeCompte, a research associate professor at Elizabeth City State University and lead author of the newly released PNAS article.
Catastrophic explanations for geological events have been out of favor for most of two centuries. Alvarez’ Dinosaur Killer asteroid was one of the first non-uniformitarian ideas to gain general acceptance, but the that happened safely in the distant past. We know that something hit Siberia just over a century ago – the idea that something larger and more devastating hit us doesn’t seem like that unreasonable of an idea.
Just imagine what that would have looked like. | 0.828264 | 3.265758 |
A comet solely simply found in December of last year has already met its demise. It did not attain perihelion or its closest method to the Sun. It did not even move inside Earth orbit. Yet Comet C/2019 Y4 (ATLAS) has now completely shattered.
In pictures taken on April 20 and April 23, the Hubble Space Telescope has captured a minimum of 30 and 25 fragments of the comet, respectively, traveling collectively in a cluster as they proceed in the direction of the interior Solar System.
The fragmentation of C/2019 Y4 (ATLAS) has fairly dashed hopes that the comet could be seen to the bare eye from Earth, even in daylight. However, though it isn’t unusual for comets to shatter as they close to the Solar, catching one within the act in such spectacular element is uncommon.
Hubble has managed to resolve particular person items of the comet – regarded as initially as much as 200 meters (650 ft) throughout – as small as the dimensions of a home, from a distance of 145 million kilometers (90 million miles).
And people chunks might present clues as to the mechanism behind the fragmentation of those peripatetic chunks of ice and rock – a course of we nonetheless do not absolutely perceive.
We predict it has to do with the sublimation of cometary ices because the comet nears and is warmed by the Sun. This outgassing produces the basic comet halo and tail. However, as these gases go away the comet, they will act as a type of jet, propelling the comet to spin.
If this spin turns into quick sufficient, centripetal forces might exceed the fabric power of the nucleus to the extent that the comet splits and fragments below the stress. | 0.85245 | 3.501858 |
Like amorphous, billowing, darkish phantoms, full-size molecular clouds of bloodless gas and dust sail through the Space among stars in our Milky Way Galaxy. In the depths of those frigid behemoths, fiery and great toddler stars are born, glowing with their newly ignited flames, as they burst into existence within these mysterious, floating stellar cradles that populate our Galaxy in abundance. In July 2014, it was announced that astronomers had captured a lovely new picture of a touch-regarded celebrity formation place referred to as Gum 15, a sparkling cloud of dust and fuel, that is the doomed cradle of a set of searing-hot, brilliantly glowing child stars. As lethal as they are beautiful, these stellar toddlers form the arrival of the nebula from which they were born–and, as they development into stellar maturity, they may sooner or later additionally ruin it.
The new image become taken as part of the European Southern Observatory’s (ESO’s) Cosmic Gems software the usage of the Wide Field Imager at the MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile. The photo suggests Gum 15, which dwells approximately three,000 light-years from Earth within the constellation Vela the Sails. The glowing nebula is a dramatic example of what is called an HII location. Giant, darkish molecular clouds are the precursors of HII regions, and those widespread clouds can exist in a solid country for extraordinarily lengthy intervals of time. However, collisions between giant molecular clouds, magnetic interactions, and supernovae can cause fall apart–after which, by manner of this disintegrate and fragmentation, child stars are born.
HII areas are well-known for creating a number of the most beautiful and breathtaking celestial gadgets astronomers can have a look at. Hydrogen (H) is the maximum abundant atomic element in the Cosmos–in addition to the lightest–and it can be discovered honestly everywhere that astronomers look. HII regions are unique, however, due to the fact they harbor huge portions of ionized hydrogen. Ionized hydrogen consists of hydrogen atoms that have had their electrons torn from them by way of excessive electricity interactions with ultraviolet photons (debris of light). As the ionized hydrogen nuclei try and snare their lost electrons, they emit mild at differing characteristic wavelengths. It is the sort of wavelengths of light that offers Gum 15 its lovely, glowing reddish colour–a shape of light that astronomers time period hydrogen alpha.
These reddish, glowing HII regions of ionizing photons originate from searing-warm toddler stars which can be cradled in the vicinity–and that is precisely what is occurring within Gum 15! One such responsible younger megastar is dubbed HD 74804, and it’s far the maximum extraordinary member of a stellar cluster called Collinder 197.
The Gum Catalog is an astronomical catalog list 84 emission nebulae that dance round inside the southern sky. The catalog changed into created by way of Colin Stanley Gum (1824-1960), who become an Australian astronomer of the Mount Stromlo Observatory. Gum evolved his catalog by way of the use of extensive area images, after which published his discoveries in 1955 in a observe entitled A take a look at of diffuse southern H-alpha nebulae. This catalog provided the eighty four nebulae–or nebular complexes.
The Gum Nebula is named for Colin Stanley Gum, who at the start dubbed it Gum 12 whilst he first spotted it, placed within the southern constellations Vela and Puppis. The nebula, now known as Gum 15, is an emission nebula that is believed to be the greatly multiplied, and nevertheless expanding, remant of a supernova that blew up about one million years ago. It carries the more youthful, smaller Vela Supernova Remnant, along with the Vela Pulsar.
Enormous molecular clouds are stellar nurseries–megastar factories that function the extraordinary cradles for glittering, hot baby stars. These colossal darkish clouds are made up in general of hydrogen gasoline, but additionally they contain tiny amounts of cosmic dust.
Astronomers examine these almost eerie, large clouds in order to gain a higher expertise of the mysterious delivery process of toddler stars. All stars are born in the secret, billowing depths of such clouds, when specially dense wallet collapse under the heavy weight in their very own merciless gravity–hence giving start to extremely good, searing-warm neonatal stars, or protostars. Within those bloodless, large clouds, fragile threads of famous person-birthing stuff intertwine–after which clump together and keep growing in length for hundreds of thousands of years. The squeeze of relentless gravity in the end causes the hydrogen atoms, which are floating around inside these very dense wallet, to suddenly fuse. This lights the toddler famous person‘s trendy, ferociously hot, glaring stellar fireplace. The bright new young star’s hearth will flame for so long as the celebrity “lives”!
The system termed nuclear fusion is what ignites a child superstar! Glittering, glowing stellar toddlers are compelled to stability very antagonistic forces so as to attain obtrusive stellar maturity. Indeed, all predominant-sequence (hydrogen burning) stars, irrespective of their age, have to always keep a precious balance among gravity and radiation strain. Gravity mercilessly seeks to pull in the surrounding nourishing gas to feed the hungry neonatal superstar, whilst radiation stress–the end result of nuclear fusion reactions–seeks to push the whole lot out and faraway from the big name, hence preserving it bouncy in opposition to the squeeze of gravity. This extraordinarily crucial and treasured stability among the continuously warring gravity and radiation stress keeps a celeb “alive”, and on the primary-series. Alas, while a star at remaining grows old, and has managed to use up its essential supply of nourishing hydrogen fuel, its middle collapses–and this heralds its inevitable dying. Small stars, like our Sun, die lightly and very superbly, puffing off their multicolored outer gaseous layers into interstellar Space. The left-over center of a small Star like our very own Sun becomes a tiny (by way of superstar-requirements) stellar relic termed a white dwarf. More large stars do not die lightly, in the cute manner of their smaller, glowing relatives. When a massive celebrity reaches the quit of that lengthy stellar street, it dies inside the fiery fury of a Type II (middle-fall apart) supernova explosion.
The Orion Nebula was the first recognized HII place to be discovered, but the Trifid Nebula is a quite higher known. The Trifid Nebula turned into first observed by way of the French astronomer Charles Messier in June 1764. Observations that had been conducted about 60 years later by way of the famous British astronomer John Herschel discovered that the cosmic cloud changed into separated into a trio of lobes, which is why it changed into named Trifid!
Once the energetic, younger stars inhabiting an HII region have end up babies, leaving their infancy behind, ferocious winds of soaring debris swim screaming faraway from these big stars, as a result shaping and hurling away the ambient gases. When the most huge of those young and very lively stars dwelling inside Gum 15 begin to attain the stop of the road, and are doomed to die, Gum 15 will die right along with them! Some stars are so huge that they will infrequently perish with merely a whimper. Instead they’ll blast themselves to smithereens within the raging wrath of a supernova conflagration–hurling away forevermore the remnant final stays of HII areas. These very deadly, huge stars, within the violence in their explosive dying throes, will depart behind them a sparkling cluster of infant stars!
Obtaining pictures of celestial items is a completely essential part of getting to know greater about our mysterious Universe. The new picture indicates Gum 15 in awesome element, and this will permit astronomers to higher apprehend the superstar-birthing area when it is studied within the future. ESO’s primary mission can be to provide present day studies centers to astronomers and astrophysicists–however the effective telescopes additionally monitor that Space may be breathtakingly lovely! | 0.90102 | 3.904003 |
Space.com reports that water ice has been discovered at the north pole of the moon. NASA announced that millions of tons of water ice exist on the moon. Scientists hope that this new finding could result in more exploration of the moon as an operational and scientific destination. This water could be used as an essential resource to produce oxygen or rocket fuel to support a future moon base.
Jason Crusan is a program executive for NASA's space operations program in Washington, D.C. As he told Space.com, "After analyzing the data, our science team determined a strong indication of water ice, a finding which will give future missions a new target to further explore and exploit." NASA further shares that more than 40 craters ranging from 1 mile to 9 miles wide were found to contain water ice. This was detected by NASA's Mini-SAR radar instrument on India's Chandrayaan-1 lunar orbiter.
Finding such large amounts of water ice on the moon is extremely exciting for scientists. The water could serve as a natural resource for astronauts, whether to drink or to be used for producing oxygen or rocket fuel. Since the ice was discovered in permanently shadowed craters at the moon's north pole, experts expect that it will remain permanently frozen. These regions are in constant darkness, so it is unlikely that water will ever melt.
Just what does all this water mean for future moon colonists? Experts report that a ship carrying people to the moon could fuel up upon landing for the return trip. This means they would not have to transport the fuel for their return or for trips beyond the moon. Further, the water could be used as a shield from cosmic radiation. Peter Schultz is a professor of geological sciences at Brown University and a consultant on a recent probe for lunar water. As he told Space.com, "We now can say ... that the possibility of living off the (lunar) land has just gone up a notch.”
NASA had planned to send astronauts to the moon in 2020 as part of the Constellation program. But last month President Obama ordered NASA to cancel Constellation and instead focus on using commercial spacecraft to launch American astronauts to orbit rather than landing on the moon. Ultimately, this was to direct NASA to send astronauts to more stable points in space, like certain asteroids or the moons of Mars. Now hopes are that the moon can be seen as a stepping stone to Mars.
In the meantime, India is prepping for more moon exploration. They launched the Chandrayaan-1 moon probe in October 2008. Chandrayaan means “moon craft” in Sanskrit. Space.com reports that the Chandrayaan-2 mission is set to launch in 2013.
For further reading: | 0.870863 | 3.090341 |
Newswise — A team of astronomers led by Michaël Gillon, of the Institut d'Astrophysique et Géophysique at the University of Liège in Belgium, have used the Belgian TRAPPIST telescope to observe the star 2MASS J23062928-0502285, now also known as TRAPPIST-1. They found that this dim and cool star faded slightly at regular intervals, indicating that several objects were passing between the star and the Earth . Detailed analysis showed that three planets with similar sizes to the Earth were present.
TRAPPIST-1 is an ultracool dwarf star -- it is much cooler and redder than the Sun and barely larger than Jupiter. Such stars are both very common in the Milky Way and very long-lived, but this is the first time that planets have been found around one of them. Despite being so close to the Earth, this star is too dim and too red to be seen with the naked eye or even visually with a large amateur telescope. It lies in the constellation of Aquarius (The Water Carrier).
Emmanuël Jehin, a co-author of the new study, is excited: "This really is a paradigm shift with regards to the planet population and the path towards finding life in the Universe. So far, the existence of such 'red worlds' orbiting ultra-cool dwarf stars was purely theoretical, butnow we have not just one lonely planet around such a faint red star but a complete system of three planets!"
Michaël Gillon, lead author of the paper presenting the discovery, explains the significance of the new findings: "Why are we trying to detect Earth-like planets around the smallest and coolest stars in the solar neighbourhood? The reason is simple: systems around these tiny stars are the only places where we can detect life on an Earth-sized exoplanet with our current technology. So if we want to find life elsewhere in the Universe, this is where we should start to look."
Astronomers will search for signs of life by studying the effect that the atmosphere of a transiting planet has on the light reaching Earth. For Earth-sized planets orbiting most stars this tiny effect is swamped by the brilliance of the starlight. Only for the case of faint red ultra-cool dwarf stars -- like TRAPPIST-1 -- is this effect big enough to be detected.
Follow-up observations with larger telescopes, including the HAWK-I instrument on ESO's 8-metre Very Large Telescope in Chile, have shown that the planets orbiting TRAPPIST-1 have sizes very similar to that of Earth. Two of the planets have orbital periods of about 1.5 days and 2.4 days respectively, and the third planet has a less well determined period in the range 4.5 to 73 days.
"With such short orbital periods, the planets are between 20 and 100 times closer to their star than the Earth to the Sun. The structure of this planetary system is much more similar in scale to the system of Jupiter's moons than to that of the Solar System," explains Michaël Gillon.
Although they orbit very close to their host dwarf star, the inner two planets only receive four times and twice, respectively, the amount of radiation received by the Earth, because their star is much fainter than the Sun. That puts them closer to the star than the habitable zone for this system, although it is still possible that they possess habitable regions on their surfaces. The third, outer, planet's orbit is not yet well known, but it probably receives less radiation than the Earth does, but maybe still enough to lie within the habitable zone.
"Thanks to several giant telescopes currently under construction, including ESO's E-ELT and the NASA/ESA/CSA James Webb Space Telescope due to launch for 2018, we will soon be able to study the atmospheric composition of these planets and to explore them first for water, then for traces of biological activity. That's a giant step in the search for life in the Universe," concludes Julien de Wit, a co-author from the Massachusetts Institute of Technology (MIT) in the USA.
This work opens up a new direction for exoplanet hunting, as around 15% of the stars near to the Sun are ultra-cool dwarf stars, and it also serves to highlight that the search for exoplanets has now entered the realm of potentially habitable cousins of the Earth. The TRAPPIST survey is a prototype for a more ambitious project called SPECULOOS that will be installed at ESO's Paranal Observatory .
TRAPPIST (the TRAnsiting Planets and PlanetesImals Small Telescope) is a Belgian robotic 0.6-metre telescope operated from the University of Liège and based at ESO's La Silla Observatory in Chile. It spends much of its time monitoring the light from around 60 of the nearest ultracool dwarf stars and brown dwarfs ("stars" which are not quite massive enough to initiate sustained nuclear fusion in their cores), looking for evidence of planetary transits.The target in this case, TRAPPIST-1, is an ultracool dwarf, with about 0.05% of the Sun's luminosity and a mass of about 8% that of the Sun.
This is one of the main methods that astronomers use to identify the presence of a planet around a star. They look at the light coming from the star, to see if some of the light is blocked as the planet passes in front of its host star on the line of sight to Earth -- transits the star, as astronomers say. As the planet orbits around its star, we expect to see regular small dips in the light coming from the star as the planet moves in front of it.
SPECULOOS is mostly funded by the European Research Council and led also by the University of Liège. Four 1-metre robotic telescopes will be installed at the Paranal Observatory to search for habitable planets around 500 ultra-cool stars over the next five years.
This research was presented in a paper entitled "Temperate Earth-sized planets transiting a nearby ultracool dwarf star", by M. Gillon et al., to appear in the journal Nature.
The team is composed of: M. Gillon (Institut d'Astrophysique et Géophysique, Université de Liège, Belgium), E. Jehin (Institut d'Astrophysique et Géophysique, Université de Liège,Belgium), S. M. Lederer (NASA Johnson Space Center, USA), L. Delrez (Institut d'Astrophysique et Géophysique, Université de Liège,Belgium), J. de Wit (Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, USA), A. Burdanov (Institut d'Astrophysique et Géophysique, Université de Liège, Belgium), V. Van Grootel (Institut d'Astrophysique et Géophysique, Université de Liège,Belgium), A. J. Burgasser (Center for Astrophysics and Space Science, University of California, San Diego, USA and Infrared Telescope Facility, operated by the University of Hawaii), C. Opitom (Institut d'Astrophysique et Géophysique, Université de Liège, Belgium), A. H. M. J. Triaud (Cavendish Laboratory, Cambridge, UK), B-O. Demory (Cavendish Laboratory, Cambridge, UK), D.K. Sahu (Indian Institute of Astrophysics, Bangalore, India), D. B. Gagliuffi (Center for Astrophysics and Space Science, University of California, San Diego, USA and Infrared Telescope Facility, operated by the University of Hawaii), P. Magain (Institut d'Astrophysique et Géophysique, Université de Liège,Belgium) and D. Queloz (Cavendish Laboratory, Cambridge, UK).
ESO is the foremost intergovernmental astronomy organisation in Europe and the world's most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world's largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become "the world's biggest eye on the sky".
* TRAPPIST is the acronym of "TRAnsiting Planets and PlanetesImals Small Telescope", more information here - http://www.eso.org/public/teles-instr/lasilla/trappist/ and at the TRAPPIST website - http://www.orca.ulg.ac.be/TRAPPIST/Trappist_main/Home.html
* SPECULOOS is the acronym of "Search for habitable Planets EClipsing ULtra-cOOl Stars". For more information, see here - http://www.orca.ulg.ac.be/SPECULOOS/Speculoos_main/Home.htmlContacts
Michaël GillonUniversity of LiegeBelgiumTel: +32 43 669 743Cell: +32 473 346 402Email: [email protected]
Julien de WitMITCambridge, Massachusetts, USAEmail: [email protected]
Richard HookESO Public Information OfficerGarching bei München, GermanyTel: +49 89 3200 6655Cell: +49 151 1537 3591Email: [email protected]
MEDIA CONTACTRegister for reporter access to contact details | 0.872914 | 3.838357 |
Using data from the Kepler space telescope, scientists have discovered a horde of six planets orbiting a sun-like star, approximately 2,000 light years from Earth. This is the largest group of planets detected so far around another star. The planets in this newly found solar system are relatively small – they range from 2.3 to 13.5 times the mass of the Earth – and are amazing mix of rock and gases. All six planets are crowded within an orbit the size of Venus’ orbit around our Sun; however, the inner five are closer to their star than any planet in our solar system.
“This is a surprisingly flat and compact system of six transiting planets,” said Jack Lissauer, co-investigator on the Kepler mission, speaking at a press conference on February 2, 2011. “The five inner planets are especially close together, something we didn’t think would happen for worlds of this size. This discovery forces us to go back and look at formation models of planets.”
Lissauer added that the close proximity of the six worlds around the star — now called Kepler 11 — also means that the planets are perturbing each others’ orbits. While having a multi-planet system makes it difficult to untangle the signals from each planet, it has the added benefit of providing more information about each of the worlds.
“In a system where the planets are tugging on one another, that means we can weigh the planets,” Lissauer said. “We have found they are low density planets; some are fluffy, sort of like marshmallows. But they are not all gas, so maybe like a marshmallow with a little hard candy at the core.”
Lissauer was incredibly enthusiastic about the discovery.
“We really were just amazed at his gift that nature has given us,” he said. “With six transiting planets, and five so close and getting the sizes and masses of five of these worlds, there is only one word that adequately describes the new finding: Supercalifragilisticexpialidocious.”
Kepler finds planets by using the transit method. The planets’ orbits are edge-on as seen from Earth, so when they pass in front of their star they block a small portion of its light. That dip in brightness is what Kepler detects.
Lissauer explained the animation (seen at the top of this article): “This is the view of Kepler, and it looks like a very special clock, one with six hands moving at six different rates, and we interpret this as six planets orbiting near the same plane. Then, you can see how it might look face on. This is the most compact system of planets every discovered by any technique anywhere.”
The time between transits provides the orbital period. To determine the planets’ masses, the scinetists analyzed slight variations in the orbital periods caused by gravitational interactions among the planets.
Lissauer said the five close inner bodies tug on one another’s orbit, and sometimes the pull can retard the transit time by 10-20 minutes.
“The timing of the transits is not perfectly periodic, and that is the signature of the planets gravitationally interacting,” said Daniel Fabrycky, a Hubble postdoctoral fellow at UC Santa Cruz, who led the orbital dynamics analysis. “By developing a model of the orbital dynamics, we worked out the masses of the planets and verified that the system can be stable on long time scales of millions of years.”
Five of the planets’ orbital periods are all less than 50 days, and the sixth planet is larger and farther out, with an orbital period of 118 days and an undetermined mass.
Finding a large multiplanet system has many people wondering when Kepler will discover an Earth-like world. The scientists on the panel today estimated it will take three years of Kepler data to find another Earth.
“No one is more eager to get to the point of an Earth-like planet than the Kepler team,” said Douglas Hudgins, Kepler program scientist. That will require at least 3 years of Kepler data and painstaking follow-up observations from ground-based before those types of discoveries will emerge from the data.”
Hudgins reminded everyone that the first 15 years of exoplanet searches from ground-based observing produced about 500 planets, and that last year the Kepler team announced 750 exoplanet candidates from just the first three months of Kepler observations. With the release of more Kepler data today, there are now more than 1,200 planet candidates.
“The key thing to remember about every planet candidate,”Hudgins said, “ is that every time we see in data evidence of a signal, there is required analysis and follow-up data and observations to determine it is actually planet and not something masquerading as a planet.”
Translation: this takes time and won’t happen overnight.
But with the release of more data, the Kepler team said they wants to harness the horsepower of the whole planetary community, as well as citizen scientists to scour through the data. The Planet Hunters program from Galaxy Zoo has been a successful project that allows anyone to contribute the science of finding extrasolar planets.
The public has made over 1.3 million classification using just the first 30 days of publicly released Kepler data,” said Debra Fischer, professor of Astronomy at Yale University who heads up the Planet Hunters project. “We are really excited and appreciative that NASA and the Kepler mission has essentially quadrupled the amount of public data with the early release of their latest data.” | 0.818551 | 3.838518 |
Mini-moon: Smallest full moon of 2011 rises tonight
Bigger isn't always better.
So tonight, why not get outside and look up at what astronomers say will be -- or rather, will appear to be -- the smallest full moon of 2011?
According to astronomy expert Joe Rao, the smallest full moon of 2011 will be 12.3% smaller than the largest full moon of 2011, which occurred in March.
The difference in perceived size is due to the moon's elliptical orbit. In March, the moon turned full just minutes away from the perigee of its orbit, or the point at which the moon is closest to Earth. Tonight's full moon will reach its fullness peak at 7:06 p.m. PDT; just a few hours later, at 5 a.m., the moon will hit the apogee of its orbit, or point at which the moon is the farthest from Earth.
The perigee and apogee of the moon's orbit change each month, but in March the moon was 221,565 miles from Earth when it appeared to be full; tonight, the moon will be 252,546 miles from Earth when it appears full.
For those who don't have a calculator handy, that's a difference of 30,981 miles.
So will we be able to notice the difference?
"I really should say no, because 12% is just not that much of a change,"said Steve Edberg, an astronomer at the Jet Propulsion Laboratory in an interview with The Times. "But to someone who was paying close attention and remembered what the moon looked like in March, there's a difference. And there is quite a noticeable difference in pictures."
The October full moon is traditionally called the hunter's moon, and like the harvest moon -- which occurred in September -- will appear to be full for longer than normal. All this light could have helped hunters in their pursuit of prey.
One thing we're wondering: What does one call the smallest full moon of the year? News outlets dubbed the largest moon of the year a super-moon. Perhaps we should call tonight's underwhelming lunar display a mini-moon.
Image: This picture of the largest full moon of 2011 was taken in March. Tonight, lunar observers can witness the smallest moon of 2011. Credit: Lawrence K. Ho / Los Angeles Times. | 0.818805 | 3.067449 |
In 1610, Galileo’s observed four satellites orbiting the distant gas giant of Jupiter. This discovery would ignite a revolution in astronomy, and encouraged further examinations of the outer Solar System to see what other mysteries it held. In the centuries that followed, astronomers not only discovered that other gas giants had similar systems of moons, but that these systems were rather extensive.
For example, Uranus has a system of 27 confirmed satellites. Of these, Oberon is the outermost satellite, as well as the second largest and second most-massive. Named in honor of a mythical king of fairies, it is also the ninth most massive moon in the Solar System.
Discovery and Naming:
Discovered in 1787 by Sir William Herschel, Oberon was one of two major satellites discovered in a single day (the other being Uranus’ moon of Titania). At the time, he reported observing four other moons; however, the Royal Astronomical Society would later determine that these were spurious. It would be almost five decades after the moons were discovered that an astronomer other than Herschel observed them.
Initially, Oberon was referred to as “the second satellite of Uranus”, and in 1848, was given the designation Uranus II by William Lassell. In 1851, Lassell discovered Uranus’ other two moons – later named Ariel and Miranda – and began numbering them based on their distance from the planet . Oberon was thus given the designation of Uranus IV.
By 1852, Herschel’s son John suggested naming the moon’s his father observed Oberon and Titania, at the request of Lassell himself. All of these names were taken from the works of William Shakespeare and Alexander Pope, with the name Oberon being derived from the King of the Fairies in A Midsummer Night’s Dream.
Size, Mass and Orbit:
With a diameter of approx. 1,523 kilometers, a surface area of 7,285,000 km², and a mass of 3.014 ± 0.075 x 10²¹ kilograms, Oberon is the second largest, and second most massive of Uranus’ moons. It is also the ninth most massive moon in the solar system.
At a distance of 584,000 km from Uranus, it is the farthest of the five major moons from Uranus. However, this distance is subject to change, as Oberon has a small orbital eccentricity and inclination relative to Uranus’ equator. It has an orbital period of about 13.5 days, coincident with its rotational period. This means that Oberon is a tidally-locked, synchronous satellite with one face always pointing toward the planet.
Since (like all of Uranus’ moons) Oberon orbits the planet around its equatorial plane, and Uranus orbits the Sun almost on its side, the moon experiences a rather extreme seasonal cycle. Essentially, both the northern and southern poles spend a period of 42 years in complete darkness or complete sunlight – with the sun rising close to the zenith over one of the poles at each solstice.
So far, the only close-up images of Oberon have been provided by the Voyager 2 probe, which photographed the moon during its flyby of Uranus in January 1986. The images cover about 40% of the surface, but only 25% of the surface was imaged with a resolution that allows geological mapping.
In addition, the time of the flyby coincided with the southern hemisphere’s summer solstice, when nearly the entire northern hemisphere was in darkness. This prevented the northern hemisphere from being studied in any detail. No other spacecraft has visited the Uranian system before or since, and no missions to the planet are currently being planned.
Oberon’s density is higher than the typical density of Uranus’ satellites, at 1.63 g/cm³. This would indicate that the moon consists of roughly equal proportions of water ice and a dense non-ice component. The latter could be made of rock and carbonaceous material including heavy organic compounds.
Spectroscopic observations have confirmed the presence of crystalline water ice in the surface of the moon. It is believed that Oberon, much like the other Uranian moons, consists of an icy mantle surrounding a rocky core. If this is true, then the radius of the core (480 km) would be equal to approx. 63% of the radius of the moon, and its mass would be around 54% of the moon’s mass.
Currently, the full composition of the icy mantle is unknown. However, it it were to contain enough ammonia or other antifreeze compounds, the moon may possess a liquid ocean layer at the core–mantle boundary. The thickness of this ocean, if it exists, would be up to 40 km and its temperature would be around 180 K.
It is unlikely that at these temperatures, such an ocean could support life. But assuming that hydrothermal vents exist in the interior, it is possible life could exist in small patches near the core. However, the internal structure of Oberon depends heavily on its thermal history, which is poorly known at present.
Oberon is the second-darkest large moon of Uranus (after Umbriel), with a surface that appears to be generally red in color – except where fresh impact deposits have left neutral or slightly blue colors. In fact, Oberon is the reddest moon amongst its peers, with a trailing hemisphere that is significantly redder than its leading hemisphere.
The reddening of the surfaces is often a result of space weathering caused by bombardment of the surface by charged particles and micrometeorites over many millions of years. However, the color asymmetry of Oberon is more likely caused by accretion of a reddish material spiraling in from outer parts of the Uranian system.
Oberon’s surface is the most heavily cratered of all the Uranian moons, which would indicate that Oberon has the most ancient surface among them. Consistent with the planet’s name, these surface features are named after characters in Shakespearean plays. The largest known crater, Hamlet, measures 206 kilometers in diameter, while the Macbeth, Romeo, and Othello craters measure 203, 159, and 114 km respectively.
Other prominent surface features are what is known as chasmata – steep-sided depressions that are comparable to rift valleys or escarpments here on Earth. The largest known chasmata on Oberon is the Mommur Chasma, which measures 537 km in diameter and takes its name from the enchanted forest in French folklore that was ruled by Oberon.
As you can plainly see, there is much that remains unknown about this satellite. Much like its peers, how they came to be, and what secrets may lurk beneath their surfaces, is still open to speculation. One can only hope that future generations will choose to mount another Voyager-like expedition to the Outer Solar System for the sake of studying the Uranian satellites.
Astronomy Cast also has a good episode on the subject. Here’s Episode 62: Uranus. | 0.844397 | 3.890949 |
Every four years (with some extremely rare exceptions), Feb. 29 is added to our calendars. It's called a leap year or a leap day.
Why is there a leap year?
It takes about 365.25 days (more specifically 365.2422 days) for Earth to make one revolution around the sun, according to NASA. To make up for the extra time, an additional day is added to the calendar at the end of February every four years.
So in short, that's a leap year.
To break it down even further, the length of a year is based on how long it takes a planet to revolve around its sun. Since Earth's days don't perfectly line up with the Earth's orbit, an extra day is added to keep time and seasons in order.
Without a leap day, the dates of annual events, like equinoxes and solstices, would slowly shift to later in the year. NASA points out that after only a century without leap days, summer wouldn't start until mid-July.
Dr. James O'Donoghue, a planetary scientist for the Japan Aerospace Exploration Agency, posted two helpful animations online which further illustrates why Leap days exist.
O'Donoghue's animation shows just how quick our seasons would be disrupted. It reveals that without leap years, December would drift into summer in 400 years.
The leap year solution gets a little trickier because the extra .2422 day is about six hours. NASA explained if the orbit was exactly 365 days and six hours, adding a single day every four years wouldn't be a problem. However, Earth takes just a little less time than that. So, rounding up and adding an extra day every four years adds about 45 minutes, or about three full days every 400 years.
Stay with me.
To correct the extra 45 minutes, years that are divisible by 100 do not have leap days unless they also can be divided by 400.
For example, the year 2000 was a leap year (it was divisible by 100 and 400), however, the years 2100, 2200, and 2300 will not have a leap year because they aren't divisible by 400.
Scientists really planned it all out. | 0.828152 | 3.072358 |
Venus is the second planet in the solar system after Mercury. Its orbit around the sun is the most circular in comparison to other planets. After sun and moon, Venus is the brightest object in the sky, historically often referred to as the "evening star" or "morning star".
Since Venus is relatively close to the sun, Venus phases, similar to the phases of the moon, are observable from Earth. These were already recognized by Galileo Galilei and were an important clue to the heliocentric worldview developed by Copernicus.
It has long been believed that Venus is a kind of sister planet to Earth, which is true in some respects: Venus is only slightly smaller than Earth (95% of the Earth's diameter). Venus and Earth have very few impact craters, suggesting a relatively young crust. In addition, the chemical composition of both planets is similar.
Even life was suspected under the dense clouds of Venus. Recent scientific data, however, prove that Venus has a hostile atmosphere. On the surface, the pressure is 90 atm, which corresponds approximately to the pressure at 1 km ocean depth.
The several kilometers thick clouds are made of sulfuric acid, the dense atmosphere creates a greenhouse effect that raises temperatures to almost 500 ° C. The wind speeds are up to 350 km / h. In contrast to Earth, Venus also has no magnetic field, and even a moon is not yet known.
This poster shows everything important to our neighbor planet, including Venus landscapes, which were modeled on the basis of Nasa radar data. | 0.825618 | 3.400716 |
By Alan Caruba
On December 22, 1554 AD, someone took note of a celestial phenomenon during which a full lunar eclipse occurred. It will occur again on Tuesday, the day that marks the winter solstice, the shortest day of the year. Today’s astronomers will tell you it is just a coincidence and, indeed, that is all it is.
1554 had not been a good year for Lady Jane Gray who was beheaded after having spent just nine days as queen of England. The Privy Council had someone else in mind for the job. There were the usual battles in England and France where such skirmishes were what passed for politics in that era, but it was not otherwise a particularly memorable year.
For centuries, however, men had been paying close attention to the skies. In Ireland, there is a huge circular stone structure estimated to be 5,000 years old. On solstice, a single shaft of sunlight reaches deep into its central chamber at dawn. It predates the pyramids and Stonehenge, the latter of which was constructed to mark the winter and summer solstices.
Solstice celebrations clearly go back thousands of years in mankind’s history. The Neolithic peoples around the world, from about 10,000 to 3,000 BC, were the first farmers and, as a result, knowledge of the seasons and the cycles of harvest was critical.
The Moon that appeared to diminish and disappear only to reappear was of great interest as it proved an excellent way of marking time. It was, however, the solstice that was regarded as the day on which the Sun was reborn. Rebirth is a common theme in myths dating far back in history.
An excellent telling of the solstice story can be found here. “Ironically, the Earth is actually nearer to the Sun in January than it is in June—by three million miles. The Earth leans slightly on its axis like a spinning top frozen in one off-kilter position. Astronomers have even pinpointed the price angle of the tilt. It is 23 degrees and 27 minutes off the perpendicular to the plane of orbit.”
Clearly, someone was paying attention in ancient times because hundreds of megalithic structures have been found throughout Europe, each oriented to the solstices and the equinoxes. Sacred sites have been found in the Americas, Asia, Indonesia, and the Middle East.
In time, both Christmas and Hanukkah would be incorporated into the winter solstice, but the event was widely celebrated well before these holidays even existed and it was regarded as a time of magic. For the ancient Romans, of course, it was a time of feasting and, reportedly, debauchery, but just about any time of the year seemed to signal “party!” for them.
What lesson can we draw from the solstice of 2010? It is, I think, that the Earth is very old, 4.5 billion years old in fact, and what passes for human civilization is rather new by comparison. For a very long time, men peered into the sky and marveled at the Sun, Moon and stars. In time they began to make some sense of the cyclical change of seasons and apply it to agriculture and other activities.
Now consider the timeline. In 1554 someone recorded the lunar eclipse that occurred on the winter solstice, but it was not until October 1608, over fifty years later, that a device called a telescope was unveiled in the Netherlands. It made Jacob Metius of Alkmaar a tidy sum of money, but it was the genius, Galileo, who would grasp the power of the telescope. He made his first one in June or July 1609.
As this winter solstice dawns, the United States of America, the greatest pioneer of outer space, no longer has a vehicle to continue manned exploration. The Russians, with whom we were locked in conflict throughout the Cold War, now provide our astronauts a ride to the Space Station. There is something profoundly wrong about that.
© Alan Caruba, 2010 | 0.85354 | 3.482274 |
1.Question: What does the "Birth of New Moon" mean, and what is conjunction?
Answer: Conjunction or birth of new moon is the same thing. "A conjunction occurs when the Moon passes between the Earth and the Sun; but because the Moon usually passes north or south of the Earth-Sun line, it specifically occurs when the Earth-Sun-Moon plane is perpendicular to the plane of Earth's orbit around the sun." This moment is called "New Moon Birth" or conjunction. At this moment the sunlight falling on the moon cannot come to the earth. In other words new moon is "No Moon". No one can see this "New Moon" even by most powerful telescopes.
2.Question: Is it possible to see the astronomical new moon (invisible moon) using telescope?
Answer: The astronomical new moon happens when the moon comes between earth and sun, and that new moon cannot be seen by the most sophisticated telescopes. It is called invisible moon, becuase its lighted portion is towards the sun and dark portion is towards the earth.
3.Question: After the Moon Birth, how much time is required for people to sight the New Moon?
Answer: Time passed after New Moon Birth is called the age of the moon. Sighting is possible at different age in different months. So, age cannot be a criterion for sighting. Why is it so? Because, the orbit of the moon is elliptical and in its orbit, the moon moves faster when it is closer to the earth, and slower when it is farther from earth. When it moves faster, the moon becomes visible at smaller age (like 17 hours), and when it moves slower, it becomes visible at larger age (like 23 hours). The main factor that makes the moon visible is the angle between moon-earth-sun. When this angle becomes about 9 degrees, the moon starts to be visible. How much time it takes to get this angle depends upon the speed of the moon in its orbit.
4.Question: Why is the moon sometimes big and orange and sometimes small and white?
Answer: The moon travels in an orbit around the earth in an oval path, so its distance from earth varies. When it is closest to the earth it looks bigger. The colors variation is due to variation in the pressure, temperature, and humidity in the atmosphere, which goves more pronounced affect for a viewer when the moon is near the horizon.
5.Question: What is "New Moon Birth" and are there any differences in calculating the timing of the new moon birth by different people or different observatories?
Answer: The definition of "New Moon Birth" also known as "Astronomical New Moon" or "Conjunction" is the moment of time when the earth, sun and moon are in the same plane. In scientific terms, the Birth of New Moon is the time when sun's ecliptic longitude and moon's ecliptic longitude are the same with reference to the center of the earth. This could happen at any moment from 0:00 hours to 23:59 hours Greenwich Mean Time (Universal Time), and at that moment the moon is dark as seen from the earth. So, you can also think of a "New Moon" as "Dark Moon" or "Invisible Moon". Some people calculate the ecliptic longitude of the moon and sun from a specific location on the surface of the earth. This may be called as topocentric new moon or topocentric conjunction. There are different algorithms to calculate astronomical new moon (conjunction) depending upon the accuracy desired. Some are more accurate than others. Less elaborate and sufficiently accurate formulae can calculate the birth of new moon with an error up to +2 or -2 minutes, and for most practical purposes this accuracy is sufficient. So, calculations of conjunction by different algorithms may disagree slightly.
6.Question: I've been told that we always see the same side of the moon. There is always a hidden side that we can never see. Is this true? If so, why is it?
Answer: Yes, it is true. The moon rotates around its own axis in about the same time as it takes to circle the earth. These two motions cause the same side of the moon turned towards earth in general. Due to some variations in these motions and some other minor phenomena (liberation and wobbling), the people from earth can only see about 59% of the moon's surface at different times and place, which is a little more than (50% of the lunar surface) one side of the moon as seen from earth.
7.Question: The moon is the closest object to the Earth, yet we do not see it for some part of the month. Where does it go? Is it because of light or darkness?
Answer: The moon is totally dark object; it does not have any light of its own. It merely reflects sunlight falling upon it. When sun is on the opposite side of the moon looking from earth, the side of the moon facing earth is completely dark, and we can not see this moon for about 36 hour every month. On all other days, the moon is at a different angle from the sun and we see different phases of the moon. It rises and sets because of the curvature of the earth as earth revolves around its own axis.
8.Question: Is it possible for the dark moon (unilluminated) to be above the horizon after sunset before it is born? When does this happen?
Answer: Yes, it is possible. The moon quite often sets 5 to 25 minutes after sunset when new moon is not born yet, that is its age is negative. The moon can set several minutes after sunset even when there are 10 hours to go before the new moon birth. It could happen in different places on the globe in different months.
Setting of sun and moon are the functions of the curvature of the earth from a particular location. New Moon is one instant of time when one spot on earth faces the line between sun and moon. At that moment other places on earth have sunrising, sun overhead, or even midnight. Same way moon can be at different situations. Moon setting after sunset is just its position relative to sun and that position is different at different times and at different latitudes in Northern and Southern hemisphere. | 0.802422 | 3.743492 |
A molecular cloud, sometimes called a stellar nursery (if star formation is occurring within), is a type of interstellar cloud, the density and size of which permit the formation of molecules, most commonly molecular hydrogen (H2). This is in contrast to other areas of the interstellar medium that contain predominantly ionized gas.
Molecular hydrogen is difficult to detect by infrared and radio observations, so the molecule most often used to determine the presence of H2 is carbon monoxide (CO). The ratio between CO luminosity and H2 mass is thought to be constant, although there are reasons to doubt this assumption in observations of some other galaxies.
Within molecular clouds are regions with higher density, where much dust and many gas cores reside, called clumps. These clumps are the beginning of star formation if gravitational forces are sufficient to cause the dust and gas to collapse.
Within the Milky Way, molecular gas clouds account for less than one percent of the volume of the interstellar medium (ISM), yet it is also the densest part of the medium, comprising roughly half of the total gas mass interior to the Sun's galactic orbit. The bulk of the molecular gas is contained in a ring between 3.5 and 7.5 kiloparsecs (11,000 and 24,000 light-years) from the center of the Milky Way (the Sun is about 8.5 kiloparsecs from the center). Large scale CO maps of the galaxy show that the position of this gas correlates with the spiral arms of the galaxy. That molecular gas occurs predominantly in the spiral arms suggests that molecular clouds must form and dissociate on a timescale shorter than 10 million years—the time it takes for material to pass through the arm region.
Vertically to the plane of the galaxy, the molecular gas inhabits the narrow midplane of the galactic disc with a characteristic scale height, Z, of approximately 50 to 75 parsecs, much thinner than the warm atomic (Z from 130 to 400 parsecs) and warm ionized (Z around 1000 parsecs) gaseous components of the ISM. The exception to the ionized-gas distribution are H II regions, which are bubbles of hot ionized gas created in molecular clouds by the intense radiation given off by young massive stars and as such they have approximately the same vertical distribution as the molecular gas.
This distribution of molecular gas is averaged out over large distances; however, the small scale distribution of the gas is highly irregular with most of it concentrated in discrete clouds and cloud complexes.
Types of molecular cloud
Giant molecular clouds
A vast assemblage of molecular gas that has more than 10 thousand times the mass of the Sun is called a giant molecular cloud (GMC). GMCs are around 15 to 600 light-years in diameter (5 to 200 parsecs) and typical masses of 10 thousand to 10 million solar masses. Whereas the average density in the solar vicinity is one particle per cubic centimetre, the average density of a GMC is a hundred to a thousand times as great. Although the Sun is much more dense than a GMC, the volume of a GMC is so great that it contains much more mass than the Sun. The substructure of a GMC is a complex pattern of filaments, sheets, bubbles, and irregular clumps.
The densest parts of the filaments and clumps are called "molecular cores", while the densest molecular cores are called "dense molecular cores" and have densities in excess of 104 to 106 particles per cubic centimeter. Observationally, typical molecular cores are traced with CO and dense molecular cores are traced with ammonia. The concentration of dust within molecular cores is normally sufficient to block light from background stars so that they appear in silhouette as dark nebulae.
GMCs are so large that "local" ones can cover a significant fraction of a constellation; thus they are often referred to by the name of that constellation, e.g. the Orion Molecular Cloud (OMC) or the Taurus Molecular Cloud (TMC). These local GMCs are arrayed in a ring in the neighborhood of the Sun coinciding with the Gould Belt. The most massive collection of molecular clouds in the galaxy forms an asymmetrical ring about the galactic center at a radius of 120 parsecs; the largest component of this ring is the Sagittarius B2 complex. The Sagittarius region is chemically rich and is often used as an exemplar by astronomers searching for new molecules in interstellar space.
Small molecular clouds
Isolated gravitationally-bound small molecular clouds with masses less than a few hundred times that of the Sun are called Bok globules. The densest parts of small molecular clouds are equivalent to the molecular cores found in GMCs and are often included in the same studies.
High-latitude diffuse molecular clouds
In 1984 IRAS identified a new type of diffuse molecular cloud. These were diffuse filamentary clouds that are visible at high galactic latitudes. These clouds have a typical density of 30 particles per cubic centimeter.
The formation of stars occurs exclusively within molecular clouds. This is a natural consequence of their low temperatures and high densities, because the gravitational force acting to collapse the cloud must exceed the internal pressures that are acting "outward" to prevent a collapse. There is observed evidence that the large, star-forming clouds are confined to a large degree by their own gravity (like stars, planets, and galaxies) rather than by external pressure. The evidence comes from the fact that the "turbulent" velocities inferred from CO linewidth scale in the same manner as the orbital velocity (a virial relation).
The physics of molecular clouds is poorly understood and much debated. Their internal motions are governed by turbulence in a cold, magnetized gas, for which the turbulent motions are highly supersonic but comparable to the speeds of magnetic disturbances. This state is thought to lose energy rapidly, requiring either an overall collapse or a steady reinjection of energy. At the same time, the clouds are known to be disrupted by some process—most likely the effects of massive stars—before a significant fraction of their mass has become stars.
Molecular clouds, and especially GMCs, are often the home of astronomical masers.
- Craig Kulesa. "Overview: Molecular Astrophysics and Star Formation". Research Projects. Retrieved September 7, 2005.
- Astronomy (PDF). Rice University. 2016. p. 761. ISBN 978-1938168284 – via Open Stax.
- Ferriere, D. (2001). "The Interstellar Environment of our Galaxy". Reviews of Modern Physics. 73 (4): 1031–1066. arXiv:astro-ph/0106359. Bibcode:2001RvMP...73.1031F. doi:10.1103/RevModPhys.73.1031.
- Dame; et al. (1987). "A composite CO survey of the entire Milky Way" (PDF). Astrophysical Journal. 322: 706–720. Bibcode:1987ApJ...322..706D. doi:10.1086/165766.
- Williams, J. P.; Blitz, L.; McKee, C. F. (2000). "The Structure and Evolution of Molecular Clouds: from Clumps to Cores to the IMF". Protostars and Planets IV. Tucson: University of Arizona Press. p. 97. arXiv:astro-ph/9902246. Bibcode:2000prpl.conf...97W.
- "Violent birth announcement from an infant star". ESA/Hubble Picture of the Week. Retrieved 27 May 2014.
- Cox, D. (2005). "The Three-Phase Interstellar Medium Revisited". Annual Review of Astronomy and Astrophysics. 43 (1): 337–385. Bibcode:2005ARA&A..43..337C. doi:10.1146/annurev.astro.43.072103.150615.
- "APEX Turns its Eye to Dark Clouds in Taurus". ESO Press Release. Retrieved 17 February 2012.
- See, e.g., Fukui, Y.; Kawamura, A. (2010). "Molecular Clouds in Nearby Galaxies". The Annual Review of Astronomy and Astrophysics. 48: 547–580. doi:10.1146/annurev-astro-081309-130854.
- Murray, N. (2011). "Star Formation Efficiencies and Lifetimes of Giant Molecular Clouds in the Milky Way". The Astrophysical Journal. 729 (2): 133. arXiv:1007.3270. Bibcode:2011ApJ...729..133M. doi:10.1088/0004-637X/729/2/133.
- Di Francesco, J.; et al. (2006). "An Observational Perspective of Low-Mass Dense Cores I: Internal Physical and Chemical Properties". Protostars and Planets V. arXiv:astro-ph/0602379. Bibcode:2007prpl.conf...17D.
- Grenier (2004). "The Gould Belt, star formation, and the local interstellar medium". The Young Universe. arXiv:astro-ph/0409096. Bibcode:2004astro.ph..9096G. Electronic preprint
- Sagittarius B2 and its Line of Sight Archived 2007-03-12 at the Wayback Machine
- "Violent Origins of Disc Galaxies Probed by ALMA". www.eso.org. European Southern Observatory. Retrieved 17 September 2014.
- Low; et al. (1984). "Infrared cirrus – New components of the extended infrared emission". Astrophysical Journal. 278: L19. Bibcode:1984ApJ...278L..19L. doi:10.1086/184213.
- Gillmon, K. & Shull, J.M. (2006). "Molecular Hydrogen in Infrared Cirrus". Astrophysical Journal. 636 (2): 908–915. arXiv:astro-ph/0507587. Bibcode:2006ApJ...636..908G. doi:10.1086/498055.
- "Chandra :: Photo Album :: Cepheus B :: August 12, 2009".
- Friesen, R. K.; Bourke, T. L.; Francesco, J. Di; Gutermuth, R.; Myers, P. C. (2016). "The Fragmentation and Stability of Hierarchical Structure in Serpens South". The Astrophysical Journal. 833 (2): 204. arXiv:1610.10066. Bibcode:2016ApJ...833..204F. doi:10.3847/1538-4357/833/2/204. ISSN 1538-4357.
|Wikimedia Commons has media related to Molecular clouds.| | 0.928956 | 4.210679 |
When it whizzes past Earth in 2013, a newly discovered asteroid is going to miss our planet – but not by much.
The 50 m space rock is expected to come closer than many satellites, highlighting the growing need to keep watch on hazards from above.
An amateur team discovered the unusual asteroid, dubbed 2012 DA14, on 22 February. Its small size and orbit meant that it was spotted only after it had flown past Earth at about seven times the distance of the Moon.
However, current predictions indicate that on its next flyby, due on 15 February 2013, it will pass Earth at just 24 000 km – closer than many commercial satellites.
“This is a safe distance, but it is still close enough to make the asteroid visible in normal binoculars,” says Detlef Koschny, responsible for near-earth objects in ESA’s Space Situational Awareness (SSA) office.
Astronomers in Spain Spot ‘Slippery Target’
The asteroid was discovered by the La Sagra Sky Survey observatory, in the southeast of Spain, near Granada, at an altitude of 1700 m, one of the darkest, least light-polluted locations on the European mainland.
“Considering its path in the morning sky, its rather fast angular motion, the quite faint and fading brightness and its orbit high above the plane of Earth’s orbit, it was a slippery target – and easily could have escaped undetected during this Earth visit,” says Jaime Nomen, one of the discoverers.
The team use several automated telescopes to scan the sky, and the discovery came somewhat serendipitously after they decided to search areas of the sky where asteroids are not usually seen.
“A preliminary orbit calculation shows that 2012 DA14 has a very Earth-like orbit with a period of 366.24 days, just one more day than our terrestrial year, and it ‘jumps’ inside and outside of the path of Earth two times per year,” says Jaime.
While an impact with Earth has been ruled out on the asteroid’s next visit, astronomers will use that close approach for more studies and calculate the Earth and Moon’s gravitational effects on it.
“We will also be keen to see the asteroid’s resulting orbit after the next close approach in order to compute any future risk of impact,” says Detlef.
Half a Million Undiscovered Objects
The La Sagra Sky Survey is operated by the Observatorio Astronomico de Mallorca and has recently joined ESA’s SSA programme. In the future it will provide observations to the asteroid data hub that ESA is developing.
Together with information on space weather and debris, its information will help European scientists and policy-makers understand and assess hazards, particularly if an Earth-threatening asteroid is ever found.
The discovery of 2012 DA14 is particularly significant for the Agency’s SSA office, because it is typical of the estimated half a million undiscovered near-Earth objects up to 30 m across.
“We are developing a system of automated optical telescopes that can detect asteroids just like this one, with the goal of being able spot them at least three weeks before closest approach to Earth,” says Detlef.
To achieve this, ESA specialists supported by European industry are planning a network of 1 m-diameter telescopes with a combined field of view large enough to image the complete sky in one night.
The work is continuing under the Agency’s Space Situational Awareness Preparatory Programme. | 0.82078 | 3.718198 |
For thousands of years, humans have been studying the heavens, seeking to find patterns and predictability in their movements. This tradition goes all the way back to prehistory, where hunter-gatherer societies assigned characteristics to asterisms and celestial bodies. And from the 2nd millennium onward, magi and astronomers began recording the movements of the constellations and the planets through the zodiac.
By classical antiquity, attempts began to create astrolabes and other devices that would allow astronomers to know where the stars and planets were at any given time. These would eventually culminate in the creation of the orrery, a mechanical device that attempts to recreate the Solar System and the movements of its planets and moons around our Sun.
Traditionally, an orrery is a mechanical model of the Solar System, or at least the major planets. This device is driven by a clockwork mechanism that simulates the motion of the planets (and, in some cases, major moons) around the Sun. This last feature is key, since most known orreries were produced during the early modern period and after, when the Heliocentric model of the Solar System came to be the accepted one.
Orreries are typically driven by a clockwork mechanism with a globe representing the Sun at the center, and with a planet at the end of each of the arms. They are usually not to scale, partly because of the difficulty of mechanically modeling the distances involved, the eccentricity of various planets’ orbits, and the planets’ massive differences in terms of size.
Though many working planetaria were created during Classical Antiquity, the first orrery of the modern era was produced in 1704 by clock makers George Graham and Thomas Tompion. The name is derived from Charles Boyle, the 4th Earl of Orrery, England, who commissioned famed instrument maker John Rowley to build one in 1713 based on the design of Graham and Tompion.
The Antikythera mechanism, which is dated to ca. 150 – 100 BCE, may be considered the first orrery that is still in existence. Discovered in the wreck of a ship in 1900 off the Greek island of Antikythera (hence the name), this device consisted of hand-driven mechanisms that represented the diurnal motions of the Sun, the Moon, and the then-known five known planets (Mercury, Venus, Earth, Mars, Jupiter).
Reflecting the cosmological view of the Greeks, the device was geocentric in nature and was used as a mechanical calculator designed to determine astronomical positions. According to Roman philosopher Cicero (106 – 43 BCE), the Syrian-born Greek philosopher Posidonius of Rhodes (ca. 135 – 51 BCE ) built a planetary model as well. With the fall of the Roman Empire, the art would not be resurrected until the late Medieval Period.
In 1348, Italian doctor and clock maker Giovanni Dondi built the first known clock-driven mechanism which displayed the position of Moon, Sun, Mercury, Venus, Mars, Jupiter and Saturn along the ecliptic – according to the Ptolemaic (geocentric) model of the Solar system. At present, only a written account survives, but it is extremely detailed in its description of the mechanisms involved.
During the 16th century, two astronomical clocks were built for the court of William IV, Langrave of Hesse-Kassel (in modern day Bavaria, Germany). These showed the motions of the Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn based on the Ptolemaic system. These clocks are now on display at the Museum of Physics and Astronomy and the Royal Cabinet of Mathematical and Physical Instruments (in Kassel and Dresden, respectively).
Thanks to Copernicus’s proposal of the Heliocentric model of the Universe, Isaac Newton’s Law of Universal Gravitation, and other discoveries that took place during the Scientific Revolution, orreries changed significantly by the early modern period. In essence, the Heliocentric model simplified the apparent orbits of the planets around the Sun, to the point that they could be represented as simple circles or ellipses.
As noted, the first modern orrery was created in 1704 in England by clock makers George Graham and Thomas Tompion. This design was given to instrument maker Jon Rowely, who then produced a copy for the Prince Eugene of Savoy and was commissioned by his patron – Charles Boyle – to build them for himself and his son John – who would go on to become the 5th Earl of Orrery (and the 5th Earl of Cork).
Between 1665 and 1681, while in Paris, Christiaan Huygens created a heliocentric planetary machine that represented a year and the cycles of the then-known planets. He would go on to publish papers describing its functions by 1703. The painting “A Philosopher giving a Lecture on the Orrery in which a lamp is put in place of the Sun”, which Jospeh Wright completed in 1766, features a brass orrery as its centerpiece.
Between 1774 and 1781, Eisinga’s Planetarium was built in Franeker, in the Netherlands by amateur Frisian astronomer Eise Eisinga. Central to the planetarium is an orrery which shows the orbits of the planets across the width of the room’s ceiling. The clockwork machine that powers it has been in almost continuous operation since it first opened.
In 1764, Benjamin Martin invented a new type of orrery that relied on three parts – the planetarium where the planets revolved around the Sun; the tellurion, which showed the inclined axis of the Earth and how it revolved around the Sun; and the lunarium which showed the eccentric rotations of the Moon around the Earth. This allowed for a more accurate representations of the Solar System, which included the planet’s inclinations, relative to the Sun.
Today, with immense amounts of low-cost computing power available, software has been developed to calculate the relative positions and motions of Solar System bodies. Examples of these “digital orreries” include a java applet used at the Department of Physics at the University of Texas at Austin, and Orrery, a Solar System Visualizer from The Geometry Center at the University of Minnesota (which relies on Unix).
There is also the Digital Orrery, a special-purpose computer designed to model the long term motions of the outer planets of the Solar System. Constructed in 1985, it was built to answer a long-standing question about the Solar System, which is whether or not it is stable (invariably, the answer was a big no). This device is now at the Smithsonian Institution in Washington, DC.
And in 2013, the first virtual orrery was created by the Cattle Point Foundation at the DARK SKY Urban Star Park, located in Oak Bay, British Columbia. The orrery is called “The Salish Sea Walk of the Planets“, and was built with Google Maps to avoid negatively impacting the park and the nearby Orca and wildlife sanctuaries. This orrery has now extended beyond the Star Park to become the world largest, covering a distance of over 8,500 km (5,300 mi).
The Sun is located in the Star Park in Oak Bay (shown above) while Pluto (the most distant “planet”) is located in Bamfield on the western side of Vancouver Island, BC. The Kuiper Belt Objects are situated north in the small towns of Ucluelet and Tofino while the farthest object within our Solar System – the Oort Cloud – is across the sea at the Canadian Embassy in Beijing, China.
Meanwhile, physical orreries still exist in many locations. For example, there’s The York Solar System Model Orrery, a special bike path constructed in 1999 and maintained by York University in the UK. Spread out along 10.3 km (6.4 miles) of the old East Coast main-line railway, this scale model of the Solar System contains all the planets of the Solar System, as well as models of the Cassini and Voyager spacecraft.
There is also the “Path of the Planets Uetliberg–Felsenegg“, which follows a hiking trail along the Albis (a chain of hills in Switzerland). The path was designed by Arnold von Rotz to be a 1:1 billion scale model of the Solar System (where 1 meter equals 1 billion km). The path runs from the towns of Uetliberg to Felsenegg (which is about 2 hours away on foot) and opened on April 26th, 1979.
Each planet is represented by a large orb that is mounted to a boulder or affixed inside one (depending on their size) and has a sign that includes the body’s place in the Solar System and their basic info (like equatorial diameter, rotational speed, etc.)
There’s also The Human Orrery, which is located at Armagh Observatory, in Northern Ireland. This orrery allows people to play the part of the planets of Mercury, Venus, Earth, Mars, Jupiter, and Saturn, as well as Ceres and two comets (1P/Halley and 2P/Encke). Due to their immense distance, and the fact the orrery is to scale, Uranus and Neptune are not included.
From our humble beginnings as hunter-gatherers who looked up at the stars and discerned patterns in their appearance, humanity has come a long way in terms of its understanding of the Universe. As we invented devices to look deeper into the night sky, and even explore space directly, our models have matured accordingly, growing in terms of accuracy and complexity.
That tradition continues, with more mission to study and explore the outer Solar System proceeding apace. Future orreries are likely to take advantage of all this, leveraging new technologies and new information to create even more detailed and interesting representations of our cosmic background!
We have written many interesting articles about the planets here at Universe Today. Here’s The Solar System Guide, What is the Geocentric Model of the Universe?, What is the Heliocentric Model of the Universe?, What is the Difference Between the Geocentric and Heliocentric model of the Solar System?, and How Many Planets are in the Solar System? | 0.83912 | 3.863122 |
On April 10, a team of researchers at the Telescope Event Horizon project showed the first ever black hole image. Indirectly, the existence of these objects, which absorb even the light, was confirmed before, but now they were first shown clearly. https://meduza.io/feature/2019/04/10/astrofiziki-vpervye-pokazali-izobrazhenie-chernoy-dyry
I asked Visiting Professor of the Laboratory of Fundamental and Applied Research of Relativistic Objects of the MIPT Universe Stanislav Babak and Head of the Laboratory Yuri Kovalev to answer common questions about black holes that were asked by young people from Europe (Germany, Czech Republic, Bulgaria).
What are black holes? What is the event horizon?
Black holes are the most compact and simplest objects in the Universe. They are described by only two parameters - mass and speed of rotation. From the point of view of astrophysics, black holes are the final stage of the evolution of stars. For example, a heavy star evolves, explodes, and its center shrinks into a black hole. The event horizon of a black hole is its conditional surface, the shell, there is no physical surface, it is just some distance from the center. This is the place where the object or the light can no longer be able to get back, because here begins a very strong gravity, which does not release objects that fall into it. This can be explained mathematically: going out of the event horizon means moving in the opposite direction in time, which is impossible from the point of view of physics.
Why are black holes so called? Can they be of some color?
One of the first names of black holes - collapsars. The name “black holes” was coined in the 20th century by journalists and taken up by one of the great scientists of the time, the American theoretical physicist John Wheeler. Why blacks? This is an object that can not emit anything, the light does not come out from there. Although this is not entirely true: black holes can emit the so-called Hawking radiation (the evaporation of black holes), but at the classical level, if the light enters them, then nothing comes out, which is why they are called “black holes” - they can not be seen . We can observe a black hole only if there is some matter around it: a gas or a nearby star, from which a black hole pulls off the shell. Thanks to gravitational waves, we can “see” two merging black holes. In fact, black holes have no color, this is a conventional name, meaning that everything falls into it and nothing comes out.
Where do black holes come from?
It depends on their mass. Black holes are small (several masses of our Sun), and can be very massive (millions of masses of the Sun). The size of black holes is proportional to their mass.
Black holes with near-solar mass could originate in the early Universe. Such a black hole can be formed by squeezing a star 20–60 times the size of our Sun, which explodes at the end of life, and what remains in the center will shrink to the size of a black hole, collapse. The masses of such black holes are limited — more than 5 solar masses, but less than 50–60 solar masses.
An example of a massive black hole was shown on April 10 thanks to the "Telescope Event Horizon", which photographed an object in the center of the galaxy M87 with a mass of billions of solar. In the center of our galaxy, too, there is a similar black hole, its mass is 4 million solar. This black hole was formed together with the Galaxy - either from a giant gas cloud that contracted and formed a black hole, or it was the first generation of heavy stars that formed the first black holes, which, in turn, merged and formed black holes the size of a thousand solar masses The main mechanism for the growth of the mass of black holes in the center of galaxies is the ingestion of gas from the environment. The more you throw into a black hole, the more it grows. Moreover, if you “throw” gas or particles into a black hole in one direction, it will still unwind.
What form are they? If everything falls into a black hole, does it have a bottom?
Black holes can be of two forms: if it almost does not rotate - spherical, and if it rotates faster - spheroidal (flattened sphere). As a rule, all black holes rotate - some faster, some slower. There is no bottom in a black hole. We do not fully understand what exactly happens in the very center where the laws of physics stop working. The general theory of relativity tells us that the curvature of space at the center of a black hole is infinite. But this only means that the theory in the center of the black hole does not work. Therefore, for example, attempts to create a quantum theory of gravity are attempts to answer what could be in the very center of a black hole. While the simplest answer is infinity, singularity. But there is nothing infinite in nature, which means that so far there is something wrong in our equation.
Why study black holes?
Quite a lot of questions about the nature of the Universe are based on the concept of black holes, so it is important for scientists to confirm experimentally this idea in order to say: “Yes, we don’t deal with nonsense, these theories are valid, our constructions are correct, and we can move on such a theoretical concept as a black hole. ” We can recall the discovery of gravitational waves - the merging of two black holes with a mass of 20-30 masses of the sun. This was also indirect evidence of the existence of black holes. The discovery of the shadow of a black hole announced on April 10 is very important because it confirms the self-consistency of our theories. The prediction was this: if in the center of the Galaxy Deva A (or Messier 87) there is a black hole weighing about 6 billion solar masses, then we will see a photon ring of light just as large as we managed to measure.
Everyone noticed that the group “Event Horizon Telescope” practically did not say a word about the center of our Galaxy. The fact is that Sagittarius A * is rather unfriendly towards us for objective physical reasons. Our central black hole has a rather small event horizon. Accordingly, the explosive processes there occur very quickly - within or less than one hour. “Telescope event horizon” is difficult to restore the picture when the black hole is changing so quickly. This can be compared with the attempts of parents to photograph their constantly spinning child - the picture is always blurry. Scientists need to learn how to restore the image in the center of our galaxy in a very short time. There are no such tools yet.
How many black holes are already open?
There are a lot of objects that behave like single black holes (they pull matter and gas on themselves). As for double black holes, according to the LIGO and VIRGO catalog, there are only 10 pairs.
Do black holes really expand endlessly, absorbing everything in their path?
Not. If you specifically throw objects into a black hole, the mass will increase, but it is very difficult to get into it. The black hole at the same time will remain very small. Stars and gas that revolve around a black hole do not threaten anything - you really need to be very close to the black hole in order for it to start absorbing them.
What happens if you get into a black hole?
When you fall into a black hole, on the one hand, you begin to flatten, on the other - very stretch. There is a well-known task: what happens to an astronaut who falls into a black hole - will he tear his head first or flatten it? The correct answer is to tear off your head at the beginning. When passing through the event horizon, space is bent, and the curvature of space quickly grows until the cosmonaut himself becomes a singularity (disappears).
Can two black holes collide? What will happen then?
Two black holes are very hard to push. To do this, they must be at a very close distance to each other. One of the ways - double stars, which both as a result of "aging" turned into black holes, then they will be close to each other from the very beginning.
For two massive black holes in colliding galaxies to be close, billions of years are needed. And they must be very close for the gravitational radiation to become such that they merge over several decades. As a result of the merging of black holes, it turns out again a black hole with a larger mass and larger in size.
I think the topic of black holes is very interesting. But young people in Europe are not particularly interested in astronomy, and in particular these issues. After all, the unknown is very interesting. For my country, a very big pride that it was Yuri Gagarin on April 12, 1961 that first flew into outer space. In Russia, it is a big holiday celebrated by youth organizations throughout Russia. Volunteers organize various events and visit the planetarium on this day. Mom told me that when she was little she wanted to become an astronaut, and this went on for almost 10 years. Now if young people in Europe want to become spontaneously, we are unlikely to hear the answer by astronauts or scientists exploring black holes. But who knows, maybe when humanity will move to Mars, thanks to Illon Mask, we can be volunteers there too). | 0.901352 | 3.946227 |
The discovery was made by the astronomer Masaya Yamada and his colleagues
Researchers from Japan have come to the conclusion that, along with the supernova remnants W44, located at a distance 10 thousand light years from Earth, can be hidden behind a cloud of interstellar gas, black hole.
The researchers used located in Chile ASTE telescope and the Japanese telescope Observatory Nobeyama.
During the study of the molecular cloud around the remnants of dead stars, researchers drew attention to the “strange” behavior of clouds of interstellar gas.
This object, called a Bullet, is moving against the rotation of our Galaxy and has tremendous kinetic energy. The velocity of the Bullet is about 120 km / h.
Scientists have proposed two hypotheses to explain the phenomenon: both are associated with the activity of a hypothetical black hole.
So, researchers believe that is located near a black hole can attract a cloud of gas that formed after the explosion of a supernova.
In this case, the mass of the black hole may reach 3.5 the mass of the sun. The second option assumes that the mysterious object moves through a gas cloud, and its weight can reach 36 solar masses.
To understand which of the hypotheses is correct, will help further research.
© 2017, paradox. All rights reserved. | 0.924549 | 3.196485 |
One of the last acts of NASA's Cassini spacecraft before it died in the Saturn's hydrogen and helium atmosphere, was to be shrouded between the planet and its rings and let them drag it around, essentially acting as a gravity probe.
Accurate measurements of Cassini's last trajectory have now given researchers the opportunity to make the first accurate estimate of the amount of material in the planet's rings, weighing them out of the strength of their gravity.
It estimates – about 40 percent of Saturn's mass Moon Mimas, which is itself 2,000 times smaller than Earth's Month – tells them that the rings are relatively recent, dating from less than 100 million years ago and perhaps recently like 1
Their young age settles down on a long-standing argument among planetary scientists. Some believed that the rings formed with the planet 4.5 billion years ago from icy wastes that remained in orbit after the formation of the solar system. Others believed that the rings were very young, and that at one point Saturn had caught an object from the Kuiper Belt or a comet and gradually reduced it to encircling rubble.
The new mass ladder is based on a measurement of how much Cassini's flight path was deflected by the gravity of the rings, as the spacecraft flew between the planet and the rings on its last set of circuits in September 2017. Initially, the deflection did not match predictions based on models of the planet and rings. At first, when the team faced too much deep wind in the atmosphere of Saturn – something impossible to observe from space – the measurements made sense so they could calculate the mass of the rings.
"The first time I looked at the data I didn't believe in because I trusted our models and it took a while to sink in that there was some effect that changed the gravity field we hadn't considered ", said Burkhard Militzer, a professor of earth and planetary science at the University of California, Berkeley, modeled on planetary interiors. "It turned out to be massive currents in the atmosphere at least 9,000 kilometers deep around the equatorial area. We provisionally believed that these clouds were like clouds on Earth that are limited to a thin layer and contain almost no mass. But on Saturn is really massive. "
They also estimated that surface clouds on Saturn's equator rotate 4 percent faster than lay 9,000 kilometers deep. The deeper layer takes 9 minutes longer to rotate than the top shoots on the equator that goes around the planet once every 10 hours, 33 minutes.
"The discovery of deeply rotating layers is a surprising revelation of the inner structure of the planet," said Cassini project researcher Linda Spilker of NASA's Jet Propulsion Laboratory in Pasadena, California. "The question is, what makes the faster rotating part of the atmosphere go so deeply, and what does it tell us about Saturn's interior."
Militzer could also expect that the world's stone core should be between 15 and 18 times the Earth's mass, which corresponds to previous estimates.
The team, led by Luciano Iess at Sapienza University in Rome, Italy, reported their results today in the journal Science .
. ] Did the rings come from the ice cold comet?
Earlier estimates of Saturn's mass – between a half and a third of Mima's mass – came from studying the density waves traveling around the rocky, icy rings. These waves are caused by the planet's 62 satellites, including Mimas, which creates the so-called Cassini division between the two largest rings, A and B. Mimas are smooth and round, 246 kilometers in diameter. It has a large battle crater that resembles Death Star from the Star Wars films.
"People didn't trust the wave measurements, because there could be particles in the rings that are massive but not participating in the waves," said militzer. "We've always suspected that there was a hidden mass that we couldn't see in the waves."
Fortunately, as Cassini approached the end of his life, NASA programmed it to perform 22 dives between the planet and the rings to probe Saturn's gravity Mark. Earth-based radio telescopes measured the spacecraft's speed within a fraction of a millimeter per square meter. Second.
The new ring mass value is in previous estimates and allows researchers to determine their age.
These age calculations, led by Philip Nicholson of Cornell University and Iess, built on a connection that scientists had previously made between the mass of the rings and their age. Lower mass points at a younger age, because the rings are first made of ice and are bright, but over time become contaminated and darkened by interplanetary waste.
"These measurements were only possible because Cassini flew so close to the surface in his final hours," said militzer. "It was a classic, spectacular way to finish the job." | 0.848583 | 4.049528 |
Issue Date: November 29, 2004
For nearly 15 years, the hubble space telescope has provided breath-taking images and other data from our solar system and beyond. It has given astronomers a view into the depths of space that hadn't been possible previously. In fact, it has been said that Hubble's impact on astronomy has been greater than that of any other instrument since Galileo's astronomical telescope.
Yet Hubble, for all its impressive results, faces an unclear future.
The renowned telescope is in need of a serious tune-up to repair and replace aging components. In the past, astronauts did this work during space shuttle missions, but the shuttle fleet is currently grounded, and the National Aeronautics & Space Administration has been forced to look for alternatives to extend the telescope's life span, including the possibility of a robotic mission.
Named for famed astronomer Edwin P. Hubble and launched in 1990 aboard the space shuttle Discovery, the Hubble mission was intended to last 15 years. Servicing missions were planned for every three to five years to replace the telescope's batteries and gyroscopic stabilizers, as needed, as well as to upgrade its scientific instruments and repair other components.
Although Hubble suffered some initial setbacks, most seriously a flawed mirror that required a shuttle repair mission in 1993 to outfit its instruments with corrective lenses, the mission has been an astounding success. The telescope, which circles Earth every 97 minutes, now has amassed a series of discoveries not even dreamed of, including the acceleration of the universe's expansion. Hubble has shown us close-ups of the early universe, black holes at the centers of galaxies, and planetary details not visible with ground-based telescopes.
With the prospect of more dazzling discoveries from Hubble, NASA decided to extend its mission lifetime by adding another shuttle servicing mission. The mission, originally scheduled for this year, would have added years to the telescope's life.
Those plans came to an abrupt halt on Feb. 1, 2003, when the space shuttle Columbia broke apart during its reentry into the atmosphere, resulting in the deaths of all seven astronauts on board (C&EN, Feb. 10, 2003, page 6). The agency immediately grounded the space shuttle fleet until it could determine the cause of the tragedy and figure out how to keep it from happening again. The group charged with this task, the Columbia Accident Investigation Board, released its report seven months after the accident (C&EN, Sept. 1, 2003, page 6).
After reviewing the report, NASA Administrator Sean O'Keefe announced in January that the scheduled Hubble shuttle servicing mission would be canceled because of safety risks. That decision meant that the telescope would have just two to three years of scientific life remaining before its components--mainly, the gyroscopes--would start to break down, leading eventually to the scope's demise.
According to Michael L. Weiss, deputy program manager for the Hubble program at Goddard Space Flight Center, Hubble has six gyroscopes but needs only three to be effectively stabilized. Now, two gyroscopes are down because of normal wear and tear. A third is predicted to fail in mid-2006.
A PLAN IS being developed to operate the telescope using two gyroscopes without significantly affecting Hubble's ability to do science. The two-gyroscope option is expected to give Hubble another nine to 12 months of scientific life, bringing it to an end sometime in late 2007, Weiss explains. A servicing mission at that point could bring the gyroscopes back up and add at least five years of scientific life to the telescope.
This potential loss of Hubble's scientific capability caused many of its supporters to cry foul. "Canceling the final servicing mission for Hubble is major surgery. It is extreme. It is irreversible," said Sen. Barbara A Mikulski (D-Md.) at a hearing following O'Keefe's announcement.
The biggest concern from the scientific community is that allowing Hubble to die before the next-generation space telescope, the James Webb Space Telescope, is launched in 2011 will result in the loss of a window into deep space. Moreover, the Webb telescope will image the infrared regions of the spectrum, whereas Hubble's instruments are tuned primarily to the visible regions. That makes Hubble unique among orbiting space telescopes.
"I don't think we have an easy replacement," says Steven Beckwith, director of the Space Telescope Science Institute (STScI), which manages Hubble's science program. "Hubble continues to provide the best angular resolution [of any telescope.] To give up that capability would be a tragic loss."
"It's always hard to see a very good, useful tool go away," says William B. Latter, an astronomer at California Institute of Technology who uses Hubble to study the late-stage evolution of stars. "It's a little difficult to accept that it could just be let go."
On the basis of an outpouring of support for Hubble's potential for continued scientific discovery, NASA reevaluated its decision to cancel the servicing mission in March and began looking at alternatives to accomplishing such a mission without the shuttle.
The agency also asked the National Academies for help in reviewing the plausibility of a shuttle servicing mission and evaluating the possibility of using robotics and other ground operation activities to extend the telescope's life. In the interim report, released in July, the committee conducting the study underscored the importance of Hubble and advised NASA to keep the option of a shuttle servicing mission on the table until robotic missions and the shuttle return-to-flight program are better assessed (C&EN, July 19, page 15).
Response by Hubble supporters to the recommendations of the interim report was optimistic. And as concerned parties await the final report--due late November or early December--the outlook remains positive. "I think saving the Hubble should be a priority, and I look forward to hearing from the National Academies and NASA as the process goes forward regarding the feasibility of a robotic servicing mission or other means to preserve the telescope's scientific missions," House Science Committee Chairman Sherwood L. Boehlert (R-N.Y.) tells C&EN.
NASA, too, is encouraged about the National Academies' support for a Hubble servicing mission, notes Michael R. Moore, program executive for Hubble. In addition to exploring the possibility of a robotic servicing mission, the agency is also keeping its options open for a shuttle mission if it's ultimately deemed safe, he says. NASA is also moving forward with a "deorbiting" mission that would bring the telescope back down to Earth in a controlled way at the end of its lifetime.
Hubble's Greatest Hits
◾ The accelerating universe: Studies of distant supernovae, which only Hubble could see, showed that the universe is expanding at an increasing rate, a result that took cosmologists completely by surprise.
◾ Supermassive black holes in the centers of galaxies: Hubble gathered definitive evidence that many galaxies are composed of stars swirling around giant black holes.
◾ Deep-field survey: Hubble spent four months imaging a dark area of the sky and found a dense collection of stars and galaxies born at the dawn of the universe. Their chaotic structure is quite different from the orderly spiral galaxies closer to us.
◾ Discovery of the first extrasolar planetary atmosphere: The number of extrasolar planets now totals over 100. Hubble was able to detect sodium in the atmosphere of one of those planets, the first ever such observation.
◾ Circumstellar disks: Astronomers had long believed that some stars could be surrounded by disks of dust, from which planets likely form. Hubble confirmed their existence.
◾ Late-stage stellar evolution: Wildly unsymmetrical clouds of gas and dust thrown off by dying stars—quite different from the spherical shapes that had long been hypothesized—have led astrophysicists to search for new models.
NASA'S MAJOR focus, however, is on determining if it can put together a robotic mission on a short timescale, Moore says. According to him, the estimated cost for such a mission is $1.3 billion, although independent estimates say this figure is closer to $2 billion. Because such a mission would have to take place by the end of 2007, this money would be needed relatively quickly.
The situation would be different if NASA decides to perform only the deorbiting mission. NASA estimates that this mission would cost $400 million to $500 million. The timescale for this mission would also be longer because the batteries--which control the vehicle life--aren't projected to expire until 2009, Moore points out. He didn't provide the cost estimates for a potential shuttle servicing mission because it is currently not an active option.
In any case, coming up with the necessary funding quickly may not be easy for NASA, because the fiscal 2005 budget is already set and does not include extra funds for a Hubble rescue mission. Moore points out, however, that NASA's lack of funds has not caused any slowdown in work on a rescue mission so far. "We will find the money somewhere in the agency to continue this work until we make a decision to go forward further or to end this particular exercise," he says.
NASA is aggressively pursuing its options. The agency has already awarded a pair of contracts for work on the project. Lockheed Martin was commissioned to develop the deorbit module, Weiss says, which will be necessary regardless of whether a servicing mission is done.
A second contract was awarded to Canada-based MD Robotics to design both a robotic arm to capture Hubble and a dexterous robot (called Dextre) to service the telescope. The joined system of the robotic components, the replacement hardware, and the deorbit module is called the Hubble Robotic Vehicle.
According to Weiss, the Hubble Robotic Vehicle will be lofted on an expendable launch vehicle and, once in space, will rendezvous with and capture Hubble. This would be the first demonstration of a robot capturing an uncontrolled spacecraft in orbit--an important capability for future space exploration objectives. At the end of the servicing mission, anything that is not needed to do the controlled reentry will be ejected, he says. The telescope will then remain in orbit until its scientific capabilities expire.
A preliminary design review is scheduled for March, Weiss says. Between now and then, he notes, those involved are continuing to refine mission designs and cost estimates.
If NASA decides to move forward with a robotic mission and finds itself short on funds, most people believe Congress will step up and fill the gap. "Hubble is an easy sell in Congress," says Alex Roland, professor of history at Duke University. "If NASA had a realistic plan and said to Congress, 'We're a billion short to save the Hubble,' I think they could probably get that money," he notes.
This current crisis is not the first hurdle that Hubble has faced. From the time the project was given the green light by Congress in 1977, this telescope has pushed the envelope. "NASA started down the path knowing that building a large telescope would be a great thing," Beckwith says. "As the agency started building the telescope, it became more difficult and more expensive than NASA had predicted, primarily because there was a lot of technology development to be done," he explains.
After several delays and at a construction cost of $1.5 billion, Hubble was ready to launch in 1986. Unfortunately, the shuttle flight that preceded its launch was the ill-fated Challenger. After an additional four-year delay, Hubble was finally launched in April 1990, having already cost taxpayers $2.5 billion, according to NASA.
Edwin P. Hubble
Like the telescope that bears his name, Edwin P. Hubble has had a major impact on astronomy. One of his most notable discoveries was that there are galaxies outside the Milky Way. Until then, it was believed that everything in the universe was part of the Milky Way.
Hubble was also responsible for proving that the universe is expanding. From his observations, he formulated Hubble's law in 1929, which says that galaxies are moving away from one another at a rate that is proportional to the distance that separates them.
Born in Missouri in 1889, Hubble studied mathematics and astronomy at the University of Chicago, earning a B.S. in 1910. He was selected as a Rhodes scholar and chose to go to Oxford University to study law. When he returned to the U.S. in 1913, he began practicing law but quickly realized that his future was in astronomy.
After receiving a Ph.D. from Yerkes Observatory at the University of Chicago in 1917 and serving in World War I, Hubble went to work at the Mount Wilson Observatory in California. He spent the rest of his career there, leaving only to serve in World War II. He died suddenly in 1953.
IN THE FEW WEEKS following Hubble's launch, all the instruments onboard were put through their paces. But when Sandra Faber, astronomy professor at the University of California, Santa Cruz, and her colleagues took a picture with Hubble's Wide Field & Planetary Camera, each star had a large, fuzzy halo. The image "was released by NASA as a great success, but privately we thought the picture didn't look right," Faber said.
A series of test images showed a fatal optical flaw. "It was an absolutely classic spherical aberration," Faber said. "At that point, we knew what was going on."
The source of the flaw was mismanufactured test optics. Faber's team designed corrections for the Wide Field & Planetary Camera using a duplicate they had in the lab. Corrective "glasses" were also made for the other three Hubble instruments. Then, astronauts aboard the space shuttle Endeavour undertook a difficult and delicate space walk, installing the new camera and a module with the other instruments' corrective mirrors.
After the repair mission, Faber's then-postdoc Jon Holtzman unveiled a crystal-clear image of a star at the American Astronomical Society's annual meeting. "It was a great moment of glory," Faber says, and "2,000 people got to their feet and roared."
Since then, Hubble has redeemed itself as one of the premier astronomical achievements of humankind. Astronomers are still lined up to use it.
The science projects that Hubble does are chosen annually via peer review. According to Beckwith, STScI gets about 1,000 proposals per year but can only afford to give time to between 150 and 200 of them.
Sometimes, the discoveries are completely unexpected. "About 50% of Hubble's major accomplishments were not predicted at the time Hubble was launched," says David Leckrone, senior project scientist for Hubble at NASA's Goddard Space Flight Center, who has worked on the telescope since 1976.
Perhaps the most startling example is the finding that the universe is expanding at an accelerating rate. Until the 1990s, scientists largely believed that the universe was decelerating. Measuring the universe's expansion rate had been one of Hubble's goals, even before launch. To that end, astronomers used both ground-based telescopes and Hubble to study a range of supernovas, or exploding stars, at different distances from Earth.
HUBBLE'S ABILITY to image supernovas extremely far away enabled astronomers to determine that the most distant supernovas are speeding away much faster than the closer ones. Hubble's law, named after the astronomer, who derived it in 1929, holds that the speed at which galaxies recede from Earth increases linearly as they become more distant. But the new Hubble telescope findings show that this speed is increasing even faster than that.
Leckrone likens it to throwing a baseball in the air and, instead of having it come down, watching it speed away.
To explain this phenomenon, cosmologists are invoking a "dark energy," an unknown repulsive force. At one point billions of years ago, the universe's expansion was actually decelerating, they believe, as gravitational attraction of the universe's mass slowed the expansion. But over time, this mysterious repulsive force began to overpower the attractive gravitational energy. The nature of this energy remains one of the biggest puzzles in cosmology, Leckrone says.
Another major accomplishment of Hubble was being the first telescope to spot the telltale signatures of supermassive black holes at the centers of galaxies. Black holes are dense collections of matter with gravitational fields so intense that light can't escape from them. Faber's team discovered the majority of black holes. Identifying black holes is very difficult, as they can't be seen directly. But they can be inferred from the behavior of nearby stars, which zip around faster than would normally be predicted. "The high resolution of Hubble allowed us to see the excess motion," Faber says.
Unencumbered by atmospheric interference, Hubble also has been able to peer farther into deep space than any other telescope. A series of surveys--intense scans of relatively unexplored regions of the sky--culminated this year in the Ultra Deep Field exposure, which pushed Hubble to the limit of optical observation. The telescope's Near Infrared Camera & Multiobject Spectrometer and its Advanced Camera for Surveys focused on a dark section of sky for a total of 1 million seconds over four months. Hundreds of objects in a chaotic jumble--galaxies that came into being when the universe was 400 million to 800 million years old--revealed themselves (C&EN, March 15, page 9).
Hubble's pioneering discovery with the deep-field survey will be followed by more surveys even further back in time. The Webb telescope will take over where Hubble leaves off, exploring deeper fields in the infrared regions of the spectrum, going back to the earliest days of the universe.
The spatial resolution of Hubble has also made possible the study of planetary nebulae, which are gas clouds expelled by dying stars. The outer envelopes of stars such as these have exhausted their nuclear fuel and are puffing out into space.
Until recently, it was believed that dying stars ejected this material in a uniform, spherical way. But Hubble has found a myriad of bizarrely shaped planetary nebulae, leading astronomers to give them colorful names, such as the "Rotten Egg Nebula" and the "Dumbbell Nebula." As a result of these discoveries, scientists are rethinking physics. "Once we had a good look, we found out it's not simple at all," Latter says. "We're scrambling to re-create a model of planetary nebula formation."
ASTRONOMERS HAVE long theorized that planets are formed from accreting disks of dust and gas orbiting a star. Hubble confirmed that prediction by directly imaging disks around young stars in the Orion nebula.
In addition to discovering more than 100 extrasolar planets, Hubble was also the first telescope to identify an atmosphere on a planet outside our solar system, detecting the spectral lines of sodium, carbon, and hydrogen around the massive planet HD209458, which is 150 light-years away.
Closer to home, the telescope has captured some of the most memorable solar system events of the decade. When the fragmented comet Shoemaker Levy crashed into Jupiter in 1994, Hubble was there to capture the bull's-eye-shaped impacts generated by the comet pieces as they plunged through Jupiter's atmosphere. "That was just so exciting--I got about two hours of sleep a night for a week, and it was worth every second," Leckrone says.
Most recently, Hubble captured a rare triple-moon eclipse on Jupiter, imaging the shadows of Io, Ganymede, and Callisto as they passed across Jupiter's face.
Astronauts have visited Hubble four times for makeovers, including the optics repair mission in 1993. During the last service mission, in 2002, astronauts installed the Advanced Camera for Surveys, an instrument that is more than 10 times more powerful than its predecessor.
Engineers purposely designed Hubble to be repeatedly refurbished. "Generally, it's very hard to build new big telescopes," Beckwith explains. "It's much easier to build smaller things, like instruments to go in existing telescopes. The pace of improvement of technology is such that you can often improve an observatory by a huge factor just by putting better instruments on an old telescope," he notes.
And that's just how Hubble has evolved. "The capabilities of the telescope now are several orders of magnitude more than when the telescope was first launched," Beckwith says, "and it's because of these refurbishing missions."
In fact, working with the telescope since the last servicing mission in 2002 was "like starting all over again," states Keith S. Noll, an astronomer at STScI who studies Kuiper Belt objects, which are icy bodies that orbit beyond Neptune. With increased resolution of four pixels for each previous one, there was "almost no comparison in quality," he says.
Hubble's serviceability is unique in the space telescope world. Other space-based observatories, like the Chandra X-ray Observatory, the Spitzer Space Telescope, and the upcoming Webb telescope, orbit much farther from Earth: Hubble's orbit is currently about 350 miles, whereas the others' orbits are orders of magnitude higher. Those telescopes have less interference from Earth's warmth and atmosphere, but it isn't possible to send a shuttle out to fix or improve them.
The Universe Is A Pretty Picture
The big thrill of the Hubble telescope is, of course, the pictures. Glowing, opulent images of stars and galaxies are tangible evidence of the astronomical wonders that Hubble is uncovering.
This steady stream of arty images provided for our enjoyment is generated largely by the Hubble Heritage Project. Headed by Keith S. Noll, astronomer at the Space Telescope Science Institute in Baltimore, the project once a month releases an image designed to elicit that 'ooh, aah' response.
'We think of ourselves as nature photographers using the world's coolest camera,' Noll says.
The project's genesis six years ago stemmed from the realization that a lot of the cutting-edge science done with Hubble, such as spectroscopy and imaging of faint objects, doesn't necessarily produce great images. So the group members, not all of whom are scientists, find exposures, most culled from an archive of Hubble data, that have potential to be great art. They then process and edit them, adding color and contrast. 'We all take turns suggesting things,' Noll says.
The group also gets a small amount of coveted time each year so they themselves can take images of objects that not only are beautiful but also can be used to do science.
SOME EXPERTS question the wisdom of a serviceable telescope. The Hubble mission has essentially been hostage to the shuttle program, so the telescope has perhaps accomplished less than it could have, some believe. "Because Hubble was designed for the shuttle, it actually made the space telescope program more vulnerable than it needed to be," Roland says.
Hubble could have been launched on an expendable launch vehicle, Roland says, and could have been placed in a better orbit and therefore have produced better science. Additionally, for the price of repairing the space telescope, NASA could have built multiple space telescopes, he says. "If one deteriorated or malfunctioned, we could simply replace it with another one more cheaply than going to repair it with the shuttle," he points out.
NASA is now looking at what procedures from the shuttle servicing mission's manifest could be done in a robotic servicing mission. Priority is given to those procedures related to the health and safety of the vehicle, according to Weiss. The next level of priority goes to items that enhance the scientific capabilities of the telescope. And finally, fixing failed or degraded components is considered.
Based on this set of priorities, the first objective would be to replace the batteries and the gyroscopes, followed by the installation of the two new scientific instruments: Wide Field Camera 3 and Cosmic Origins Spectrograph. At this point, replacing the telescope's Fine Guidance Sensors and fixing components like the Space Telescope Imaging Spectrograph, which failed in August (C&EN, Aug. 16, page 17), would be considered, Weiss explains.
"If we can pull off this robotic mission, Hubble will be even more powerful than it has been before," Leckrone says.
And that's what the folks at NASA are working toward and are optimistic will happen. "We have a team at Goddard that has pulled things off in the past that seemed to be almost impossible," Moore says. "If anyone can do it, they can," he notes.
"People really have a sense of ownership of Hubble, globally," Noll says. "So I hope that we keep this going as long as it's feasible. We've really only started to scratch the surface of what we can do."
- Chemical & Engineering News
- ISSN 0009-2347
- Copyright © American Chemical Society | 0.815536 | 3.394329 |
It has been something of a struggle over the last few centuries for exponents of the theory to convince both scientists and the public that the millions of craters that pockmark the face of the Moon are the result not of volcanic explosions but of collisions with objects from space. As long ago as the early nineteenth century, the German natural philosopher Baron von Paula Gruithuisen's declaration that the lunar craters were a consequence of 'a cosmic bombardment in past ages' was treated with contempt by 'serious' scientists. (No doubt his further claims to have uncovered evidence for the existence of humans and animals on the surface of the Moon had a little to do with this.) At the other end of the nineteenth century, the US geologist Grove Karl Gilbert tried to simulate in the laboratory the formation of the lunar craters by firing objects into powder or mud. Gilbert was perplexed, however, by the observation that only objects fired vertically produced circular craters like those that cover the lunar surface. In light of this, W. M. Smart proclaimed, in 1927, that the craters of the Moon could not be caused by impacts because 'there is no a priori reason why meteors should always fall vertically'. It was only after observing the effects of the billions of tonnes of bombs dropped in the Second World War that it began to dawn on geologists that given a violent enough explosion, a circular crater would always be formed— whatever the angle of the trajectory. In other words, the tremendous explosion generated when an object hit the Moon virtually always resulted in a circular crater. Remarkably, it took another quarter of a century for the impact origin of lunar craters to gain widespread acceptance, and even today one or two maverick scientists still support a volcanic origin in the face of overpowering evidence to the contrary. Getting any new paradigm accepted in science is a battle, and geology is no exception. Just as the proponents of the revolutionary theory of plate tectonics had initially to fight hard against reactionary forces, so those scientists who claimed that the Earth, as well as the Moon, had also taken a battering found the going difficult.
As long ago as 1905, Benjamin Tilghman proposed that Arizona's famous Barringer Crater (also now known as Meteor Crater) was the result of 'the impact of a meteor of enormous and hitherto unprecedented size'. This suggestion failed to convince, however, because a quarter of a century of excavation by Tilghman and his engineer colleague D. M. Barringer failed to find the impactor itself. We now know that this had been essentially vaporized by the enormous heat generated by the collision, but at the time the absence of a 'smoking gun' simply lent credence to those who suggested an alternative mechanism of formation.
Until well after the end of the Second World War, many Earth scientists suffered an extraordinary failure of the imagination, accepting an impact origin for the lunar craters but grabbing at any straw in order not to support an impact origin for crater structures on the surface of our own planet. Given that, due to the Earth's much greater size and stronger gravity field, it must have been struck perhaps 30 times more frequently than its nearest neighbour, this denial is even more extraordinary. Perhaps not entirely surprising, however, when we consider that the enormously dynamic nature of our planet is far from suited to the preservation of impact craters, particularly those of any great age. Because of plate tectonics, and in particular the process of subduction, through which the basaltic oceanic plates are continuously being consumed within the Earth's hot interior, some two-thirds of the Earth's surface is only a few hundred million years old. Bearing in mind that the most intense phase of bombardment occurred during the first few billion years of our planet's history, then evidence for this can now only be found in the ancient hearts of the granite continents that are immune to the subduction process. Because they have succumbed to erosion and weathering, perhaps for aeons, these craters are notoriously difficult to spot. Also, the oldest rocks, which are likely to support the most craters, are in remote areas such as Siberia, northern Canada, and Australia, and some craters are so big that their true form can only be seen from space. Today, satellites have helped in the identification of over 165 impact craters all over the world, and the idea that the Earth is susceptible to bombardment from space is now as accepted as plate tectonics.
Controversy has certainly not gone away, however, and argument continues amongst the scientific community, particularly about the frequency and regularity of impacts and— probably of most interest to the layman-about the effects of the next large impact on our civilization. The question of frequency is far from straightforward and serious disagreement exists between schools of thought that, on the one hand, support a constant flux of impactors and, on the other, advocate so-called impact clustering. Notwithstanding the very heavy bombardment of the Earth's early history, followers of impact uniformitariunism support a strike rate that is uniform and invariable. This is at variance with rival groups of scien-tistswho are promoting an alternative theory of coherentcatas-trophism, within which the Earth, for one reason or another, periodically comes under attack from increased numbers of asteroids or comets.
If we are realistically to assess the threat of future impacts to our civilization, then clearly it is vital that we resolve as soon as we can whether the number of collisions continues at its current rate or whether we have a nasty shock in store somewhere down the line. If the former proves to be correct, we can expect business as usual, meaning a collision with a 50-metre potential city-destroyer every 50 years or so, a half-kilometre small-country obliterator every ten millennia, and a 1-kilometre global impact event every 100,000 to 333,000 years—depending on whose figures you accept. Fortunately for us, gigantic extinction level events (ELEs), such as that
33 Over 165 impact craters have now been identified on Earth, many in the ancient hearts of the continents caused by the lo-kilometre monster that ended the reign of the dinosaurs 65 million years ago, appear to happen every 50 to 100 million years, so the chances of one striking the Earth soon are tiny. Based upon the above impactor strike rates, proponents of the threat from asteroids and comets come up with probabilities of dying due to an impact that really make one think. If you were able to construct a time machine and hurtled forwards to the year 1,000,2002 where you sought out and consulted the Centre for Planetary Records you would come up with a fascinating fact. The number of people killed in air (and no doubt space) crashes during the intervening million years — probably between 1 and 1.5 billion — would be less than those killed by impact events, which could total 3 billion or more, assuming two or three collisions with 1-kilometre objects. What this amounts to is that during your lifetime your chance of dying due to an asteroid or comet impact could be twice as great as being killed in an air crash; a pretty sobering thought if ever there was one. Looked at another way, if you gamble, your chance of being killed during an asteroid or comet strike is 750 times more likely than winning the UK lottery. Maybe this scares the wits out of you, but the true situation may actually be worse. If the coherent catastrophists are correct then there are certain periods in the Earth's history when our planet, or perhaps even our entire solar system, travels through a region of space containing substantially more debris than normal, resulting in a significant increase in impact events on all scales.
A number of theories lay the blame for this periodic increase in Earth-threatening space debris on the episodic disruption of the so-called Oort Cloud, a great spherical cloud of comets that envelops the entire solar system far beyond the orbit of Pluto. Typically, comets in the cloud travel along such huge orbits, which take some a quarter of the way to the nearest star, that they rarely visit the inner solar system, and then only in ones and twos. However, if some external influence were to interfere with the cloud, so the thinking goes, hundreds or thousands could have their orbits changed encouraging them to plunge Sunwards, greatly raising the threat of collision with the planets — including our own. A number of suggestions have been put forward for how the
34 The Barringer Crater (also known as Meteor Crater) in Arizona is the legacy of a collision with a small asteroid 50,000 years ago
34 The Barringer Crater (also known as Meteor Crater) in Arizona is the legacy of a collision with a small asteroid 50,000 years ago
Oort Cloud might be periodically disrupted, including due to the passage through the cloud of the mythical and much sought after planet X, which some scientists think may be orbiting far beyond frozen Pluto, or to a dark and distant stellar companion of our own Sun.
An alternative and intriguing theory, known as the Shiva hypothesis after the Hindu god of destruction and renewal, has been vigorously promoted by Mike Rampino of New York University and his colleagues, who believe that the great extinctions recognized in the Earth's geological record are the result of major impact events that happen pretty regularly every 26-30 million years. Rampino and his colleagues link this to the orbit of our solar system — including the Earth — about the centre of our Milky Way galaxy, an orbit that moves up and down in a wave-like motion. Every 30 million years or so, this undulating path takes the Sun and its offspring through the plane of our disc-like galaxy, when the gravitational pull from the huge mass of stars at the galaxy's core provides an extra tug. This, say the Rampino school, is sufficient to disturb the orbits of the Oort Cloud comets to an extent sufficient to send an influx of new comets into the heart of the solar system, dramatically raising the frequency of large impacts on the Earth. It is just a few million years now since our system last plunged through the galactic plane-could a phalanx of comets be heading for us at this very moment? By the time we find out it might very well be too late.
The Shiva hypothesis calls for a periodicity operating on truly geological timescales, and for this reason is rarely addressed in discussions of the immediate threat from impact events. Much more relevant to considerations of our own safety and survival — and that of our immediate descendants — is a proposal by UK astronomers Victor Clube and Bill Napier that the Earth is struck by clusters of objects every few thousand years, and that our planet took a serious pounding as recently as the Bronze Age—just 4,000 years ago. To find out what might cause such a worryingly recent bombardment we need to return to the Oort Cloud in deep— est space. Leaving aside disturbance of the cloud due to the passage of the solar system around the galaxy, normality sees a new comet from the cloud every now and again falling in towards the inner solar system — maybe as frequently as every 20,000 years. The newcomer is rapidly 'captured' and torn apart by the strong gravitational fields of either the Sun or Jupiter, forming a ring of debris spread out along its orbit, but concentrated particularly around the position of the ori— ginal comet itself. A large comet, broken up in this way, can 'seed' the inner solar system with perhaps a million 1-kilometre sized lumps of rock, dramatically increasing the numbers of Earth—threatening objects, and significantly rais— ing the chances of our planet being hit. Clube, Napier, and others of this particular coherent catastrophist school pro— pose that the last giant comet from the Oort Cloud entered our solar system towards the end of the last Ice Age—a mere 10,000 years or so ago— breaking up to form a mass of debris known as the Taurid Complex. Every December the Earth passes through part of this debris stream, resulting in the sometimes spectacular light show put on by the Taurid meteor storm, as small rocky fragments and gravel-sized stones burn up in the upper atmosphere. These innocuous bits and pieces only represent the tail end of the Taurid Complex, however, the heart of which contains a 5-kilometre wide Earth-crossing comet known as Encke and at least 40 accompanying asteroids any one of which would create global havoc if it struck our planet.
The distribution of debris along the Taurid Complex orbit about the Sun is rather like that of runners in a 10,000-metre race; while the majority are clustered together in a pack, the rest are dotted here and there around the track. Mostyears— according to the coherent catastrophists — the Earth's orbit crosses that of the Taurid Complex at a point where there is little debris, resulting in a pre-Christmas spectacle and little else. Every 2,500-3,000 years or so, the Earth passes through the equivalent of the runners' pack — and finds itself on the receiving end of a volley of rocky chunks perhaps up to 200-300 metres across. Benny Peiser, a social anthropologist at Liverpool's John Moores University, thinks thatjustsuch a bombardment around 4,000 years ago led to the fall of many early civilizations during the third millennium BC. He and others have interpreted contemporary accounts in terms of a succession of impacts, too small to have a global impact but quite sufficient to cause mayhem in the ancient worlds, largely through generating destructive atmospheric shock waves, earthquakes, tsunamis, and wildfires. Many urban centres in Europe, Africa, and Asia appear to have collapsed almost simultaneously around 2350 BC, and records abound of flood, fire, quake, and general chaos. These sometimes fanciful accounts are, of course, open to alternative interpretation, and hard evidence for bombardment from space around this time remains elusive. Having said this, seven impact craters in Australia, Estonia, and Argentina have been allocated ages of 4,000-5,000 years and the search goes on for others. Even more difficult to defend are propositions by some that the collapse of the Roman Empire and the onset of the Dark Ages may somehow have been triggered by increased numbers of impacts when the Earth last passed through the dense part of the Taurid Complex between 400 and 600 AD. Hard evidence for these is weak and periods of deteriorated climate attributed to impacts around this time can equallywell be explained by large volcanic explosions. In recent years there has, in fact, been a worrying tendency amongst archaeologists, anthropologists, and historians to attempt to explain every historical event in terms of a natural catastrophe of some sort-whether asteroid impact, volcanic eruption, or earthquake— many on the basis of the flimsiest of evidence. As the aim of thisvolume is to shed light on how natural catastrophes can affect us all, I would be foolish to argue that past civilizations have not suffered many times at the hands of nature. Attributing everything from the English Civil War and the French Revolution to the fall of Rome and the westward march of Genghis Khan to natural disasters only serves, however, to devalue the potentially cataclysmic effects of natural hazards and to trivialize the role of nature in shaping the course of civilization.
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This is common knowledge that disaster is everywhere. Its in the streets, its inside your campuses, and it can even be found inside your home. The question is not whether we are safe because no one is really THAT secure anymore but whether we can do something to lessen the odds of ever becoming a victim. | 0.925898 | 3.865222 |
The count now stands at 3505. And, by the time you read this, it will probably be a lot higher...
Two decades ago, the fact that other planets existed beyond your, correction, our solar system was not known for sure. The perpetual discovery of exoplanets orbiting distant stars other than our own stalwart Sun is about to sprout.
Scientists expect us to find many, many more in the coming years, and as technology improves, the number is going to shoot up. In fact, I need to almost immediately qualify myself: Nasa’s website has it at 3505 exoplanets. But, as of August 1, 2017, the wonderful sounding, Extrasolar Planets Encyclopaedia, has confirmed 3639 exoplanets. The point is that this is a rapidly expanding field – as of this summer, NASA’s Kepler mission has over 5000 candidates waiting to be welcomed into the inventory of planets.
The first exoplanet was discovered in the late 1980s by radial-velocity observations of the star Gamma Cephei. By 1992, scientifically proven discoveries began with the detection of two planets orbiting the pulsar PSR B1257+12. And while indirect methods of detection, such as radial-velocity (by which a planet’s gravitational tug on its star is measurable), and the transit method (which measures the planet’s mass by measuring how much it dims its star’s brightness), there have also been directly imaged planets, usually orbiting young stars, and whose infrared signal can be picked up.
But, what are we looking for? Why do you look at yourself in the mirror in the morning? What do you hope to see? We are looking for exoplanets because we are looking to find another “Earth”, another place to call home. We are looking for our reflection, a cosmic narcissus staring into the rippling pool of deep space.
This brings us to Trappist-1 (full designation, 2MASS J23062928-0502285), which lies in the constellation of Aquarius...
The news emanating around this solar system has led to a lot of internal excitement, for here is not only seven temperate terrestrial planets with harmoniously resonant orbits, but three of them lie in the so called habitable zone.
What this means is that, basically, these planets are more than likely similar to Earth, with water, and in the correct distance to their star so as not to be too hot, nor too cold, to support life. As we go forward, and as more data and information comes through, we will be returning more and more to this world to outline what it means exactly.
Right now, the question that is worth posing – and one that is taking on an acute relevance – is what it means exactly for humankind to discover a habitable planet much like our own, on which in fact is the trace of life itself?
This is no longer hypothetical, it is, we believe, a certainty; an inevitable outcome of this advancing and expanding field of astro science. The simple fact is – we have yet to properly talk and discuss the fallout and meaning of exoplanets.
Sure, in the U.S. there’s been one or two congressional hearings, sub-committees of outlier committees. However, there is no plan in place for not only if we discover without reasonable doubt another “Earth”, but in fact even when we are contacted by extraterrestrials. This just seems a bit short-sighted. It also, as ever, is a massive oversight in what is a valuable resource – or let’s put it this way: exoplanets might be man’s most valuable, irreducible resource discovery to date.
This century is bringing huge debates and conversations to the table between scientists, experts, and the wider civil society; never before has so much information been at hand to look at the pressing issues facing us as a species. From energy sources, disease prevention, extreme weather and geographical events and calamities, terrorism, AI, nanotechnologies, synthetic biology, GM… the list is open-ended.
We keep adding to this list, for nothing can escape what we know to be the interdependence and connectedness of living on planet Earth. Maybe the discovery of a habitable exoplanet? The conversation has only just begun. | 0.927937 | 3.679315 |
Io, satellite of Jupiter, is the most volcanically active and hottest body in the solar system.The hottest spot in the solar system is neither Mercury, Venus, nor St. Louis in the summer. Io, one of the four satellites that the Italian astronomer Galileo discovered orbiting Jupiter almost 400 years ago, takes that prize. The Voyager spacecraft discovered volcanic activity on Io over 20 years ago and subsequent observations show that Io is the most volcanically active body in the solar system. The Galileo spacecraft, named in honor of the astronomer Galileo, found volcanic hot spots with temperatures as high as 2,910 Fahrenheit (1,610 Celsius). Now computer models of volcanic eruptions on Io performed by researchers at Washington University in St. Louis show that the lavas are so hot that they are vaporizing sodium, potassium, silicon and iron and probably other gases as well into its atmosphere. | 0.834898 | 3.261722 |
The applications of nuclear technology extend beyond our planet too. Without it, space travel and exploration would be extremely difficult. It is used to generate power, but also for scientific observation purposes.
Modern space travel would be unimaginable without the power of the nucleus. Chemical energy carriers like combustible solutions do not provide the energy density required for long space missions, and the added weight for the additional fuel needed would make the mission much more difficult. Solar panels are used to power satellites but their power output depends on the distance from the sun. For longer space missions, nuclear technology offers a viable solution.
The Systems Nuclear Auxilliar Power (SNAP) program was developed by NASA to use radioisotope thermoelectric generators (RTG) for space travels. The SNAP-27 units were used to provide electricity to the Apollo Lunar Surface Experiment Packages (ALSEP) and left on the moon by several Apollo missions (Figure 1). Heat was generated through the radioactive decay of Plutonium-238 and then converted to electricity by using thermocouples, which uses the temperature difference to produce a voltage via the thermoelectric effect.
Even more modern space objects like the New Horizons probe (Figure 2) that is on a mission to leave the solar system are powered by RTGs. The heat of the RTG will also provide heat to the spacecraft while it is in the outer solar system where the radiation of the sun is too weak. The expected lifetime of the RTG will power the spacecraft up to mid to late 2030s, a decade longer than its extended mission.
Figure 1: ALSEP Apollo 14 with SNAP-27 RTG on the moon1
Figure 2: RTG of the New Horizons space prob2
In the Soviet Union, the TOPAZ nuclear reactor (Figure 3) was developed as a power source for space travels. The reactor was cooled by liquid metal and produced its electricity, other than the SNAP units with a thermionic converter. The hot electrode emits electrons thermionically to the cooler electrode. The first designs were capable of delivering electricity in the kilowatt region. The TOPAZ reactor research reached its peak with the experimental satellites Kosmos 1818 and Kosmos 1867, both powered by a TOPAZ nuclear reactor each.
Figure 3: The Topaz-1 space reactor 3
Nuclear energy gives not only power to space probes and satellites but can also be a reliable power source for robots thanks to its compact design. The “Curiosity” rover (Figure 4) , launched in November 2011, landed on Mars in August 2012 after a distance of over 600 million kilometers in space. The mission was projected to last two years of exploration on the surface of the red planet but the rover is still operating to date. The success of the rover has lead to discussions of a follow-up program under the name “Curiosity 2”.
Figure 4: Curiosity on Mars 4
3 Sputnik, A. Solomov | 0.835793 | 3.197402 |
WASHINGTON: NASA’s New Horizons mission has made surprising new discovery, and found haze and flowing ice on Pluto.
John Grunsfeld, NASA’s associate administrator for the Science Mission Directorate said that with flowing ices, exotic surface chemistry, mountain ranges, and vast haze, Pluto was showing a diversity of planetary geology that was truly thrilling.
Just seven hours after closest approach, New Horizons aimed its Long Range Reconnaissance Imager (LORRI) back at Pluto, capturing sunlight streaming through the atmosphere and revealing hazes as high as 80 miles (130 kilometers) above Pluto’s surface. A preliminary analysis of the image shows two distinct layers of haze -- one about 50 miles (80 kilometers) above the surface and the other at an altitude of about 30 miles (50 kilometers).
The hazes detected are a key element in creating the complex hydrocarbon compounds that give Pluto’s surface its reddish hue, said Michael Summers, New Horizons co-investigator at George Mason University, Virginia.
Models suggest the hazes form when ultraviolet sunlight breaks up methane gas particles -- a simple hydrocarbon in Pluto’s atmosphere. The breakdown of methane triggers the buildup of more complex hydrocarbon gases, such as ethylene and acetylene, which also were discovered in Pluto’s atmosphere by New Horizons. As these hydrocarbons fall to the lower, colder parts of the atmosphere, they condense into ice particles that create the hazes. Ultraviolent sunlight chemically converts hazes into tholins, the dark hydrocarbons that color Pluto’s surface.
The new images show fascinating details within the Texas-sized plain, informally named Sputnik Planum, which lies within the western half of Pluto’s heart-shaped feature, known as Tombaugh Regio. There, a sheet of ice clearly appears to have flowed, and may still be flowing, in a manner similar to glaciers on Earth.
Additionally, new compositional data from New Horizons’ Ralph instrument indicate the center of Sputnik Planum is rich in nitrogen, carbon monoxide, and methane ices.
At Pluto’s temperatures of minus-390 degrees Fahrenheit, these ices can flow like a glacier, said Bill McKinnon, deputy leader of the New Horizons Geology, Geophysics and Imaging team. In the southernmost region of the heart, adjacent to the dark equatorial region, it appeared that ancient, heavily-cratered terrain has been invaded by much newer icy deposits.
The New Horizons mission will continue to send data stored in its onboard recorders back to Earth through late 2016. The spacecraft currently is 12.2 million kilometers beyond Pluto, healthy and flying deeper into the Kuiper Belt. | 0.862424 | 3.886171 |
An illustration showing how Mars’s rings might look following the destruction of its moon Phobos. Image by Tushar Mittal using Celestia 2001-2010, Celestia Development Team.
While the demise of Mars’s largest moon is not anticipated for another twenty to forty million years, new research suggests Phobos will eventually be torn apart by the gravitational forces that are pulling it towards the Red Planet.
Just as Earth pulls our Moon in different directions – a force that contributes to tides on our planet – so too is Mars’s gravity pulling Phobos inwards, according to a new study.
But because Phobos is fractured and made up of porous rubble, rather than crashing into the Red Planet the moon will likely be torn apart in its atmosphere, potentially creating rings around Mars, like those around Saturn, that could last from one to one hundred million years.
Two earth scientists at the University of California, Benjamin Black and graduate student Tushar Mittal, conducted the research.
They say the largest chunks would crash into the Red Planet and create craters on the Martian surface, while much of the debris would remain in Mars’s orbit and circle the planet for millions of years before dropping to the surface in moon showers.
Mars’s other moon, Deimos, would remain.
“While our moon is moving away from Earth at a few centimetres per year, Phobos is moving toward Mars at a few centimetres per year, so it is almost inevitable that it will either crash into Mars or break apart,” Black says.
“One of our motivations for studying Phobos was as a test case to develop ideas of what processes a moon might undergo as it moves inward toward a planet.”
The researchers say this work is important in studying the planets of our early Solar System, which likely hosted many more moons that have since disintegrated into rings.
Black and Mittal examined data of fractured rocks on Earth and meteorites that have struck Earth that have a density and composition similar to Phobos.
They also looked at results from simulations of the Stickney impact crater on Phobos, which formed when a rock smashed into the Martian moon.
The crater is huge, spanning about one sixth of the lunar circumference.
The duo then modelled the predicted evolution of the ring that might form around Mars following Phobos’s demise.
“If the moon broke apart at 1.2 Mars radii, about 680 kilometres above the surface, it would form a really narrow ring comparable in density to that of one of Saturn’s most massive rings,” Mittal says.
“Over time it would spread out and get wider, reaching the top of the Martian atmosphere in a few million years, when it would start losing material because stuff would keep raining down on Mars.”
It is, however, not clear whether the rings would be visible from Earth, but they might reflect enough light to make Mars appear brighter.
“Standing on the surface of Mars a few tens of millions of years from now, it would be pretty spectacular to watch,” Black says. | 0.877448 | 3.927436 |
April Celestial Calendar by Dave Mitsky
All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)
4/1 First Quarter Moon occurs at 10:21
4/2 The Moon is 8.5 degrees south of the first-magnitude star Castor (Alpha Geminorum) at 4:00; the Moon is 4.9 degrees south of the first-magnitude star Pollux (Beta Geminorum) at 8:00; asteroid 3 Juno (magnitude +9.7) is at opposition at 20:00
4/3 The Moon is 1.3 degrees north of the bright open cluster M44 (the Beehive Cluster or Praesepe) in Cancer at 7:00; Mercury is 1.4 degrees south of Neptune at 15:00; Venus is 0.3 degree south of the bright open cluster M45 (the Pleiades or Subaru) in Taurus at 20:00
4/4 Mercury (magnitude 0.0) is 1.3 degrees south-southeast of Neptune (magnitude +8.0) at 1:00; Venus (magnitude -4.4) passes 16 arc minutes southeast of Alcyone (magnitude +2.9) at 2:00; the Moon is 3.8 degrees north-northeast of the first-magnitude star Regulus (Alpha Leonis) at 22:00
4/7 The Moon is at its closest perigee of 2020, subtending 33' 29'' from a distance of 356,907 kilometers (221,771 miles), at 18:09
4/8 The Martian northern hemisphere autumnal equinox occurs at 1:00; the Full Moon, known as the Egg or Grass Moon, occurs at 2:35; the Moon is 6.7 degrees northeast of the first magnitude star Spica (Alpha Virginis) at 12:00
4/10 Venus is at its northernmost latitude from the ecliptic plane (3.4 degrees) at 18:00
4/11 The Moon is 6.4 degrees northeast of the first magnitude star Antares (Alpha Scorpii) at 15:00
4/13 The Moon is at the descending node (longitude 271.6 degrees) at 3:00
4/14 The Moon is 1.2 degrees south of the dwarf planet Pluto, with an occultation taking place in a portion of the Antarctic peninsula, at 22:00; Last Quarter Moon occurs at 22:56; the Moon is 2 degrees south of Jupiter at 23:00
4/15 Venus is 9.9 degrees north-northwest of the first magnitude star Aldebaran (Alpha Tauri) at 2:00; the equation of time is equal to 0 at 3:00; the Moon, Jupiter, and Saturn lie within a circle with a diameter of 5.5 degrees at 7:00; the Moon is 2.4 degrees southeast of Saturn at 11:00; Jupiter is at western quadrature (90 degrees from the Sun) at 11:00
4/16 Mercury is at its southernmost latitude from the ecliptic plane (-7.0 degrees) at 11:00; the Moon is 2.0 degrees south of Mars at 5:00; the Curtiss Cross, an X-shaped clair-obscure illumination effect located between the craters Parry and Gambart, is predicted to be visible at 15:59
4/18 The Sun enters Aries (longitude 29.1 degrees on the ecliptic) at 17:00
4/19 The Moon is 3.9 degrees southeast of Neptune at 11:00; the Sun’s longitude is 30 degrees at 15:00
4/20 The Moon is at apogee, subtending 29' 24'' from a distance of 406,462 kilometers (252,564 miles), at 19:00
4/21 Saturn is at western quadrature (90 degrees from the Sun) at 7:00; the Moon is 3 degrees south of Mercury at 17:00
4/22 The peak of the Lyrid meteor shower (a zenithal hourly rate of 15 to 20 per hour) occurs at 6:00
4/23 New Moon (lunation 1204) occurs at 2:26; the Moon is 3.7 degrees southeast of Uranus at 10:00
4/24 The apparent brightness of Mars exceeds magnitude +0.5 today
4/25 Pluto is stationary in longitude, with retrograde (westward) motion to commence, at 5:00; the Moon is 6.6 degrees southeast of M45 at 10:00
4/26 Pluto is stationary in right ascension, with retrograde motion to begin, at 1:00; the Moon is 3.7 degrees north of Aldebaran at 3:00; Uranus is in conjunction with the Sun (20.811 astronomical units from the Earth, latitude -0.47 degree) at 9:00; the Moon is 0.1 degree north of asteroid 4 Vesta, with an occultation taking place in southern Japan, the Philippines, most of southeastern Asia, China, northern and central India, southern Kazakhstan, most of the Middle East, and central and northeastern Africa, at 11:00; the Moon is 5.9 degrees southeast of Venus at 18:00; the Moon is at the ascending node (longitude 90.3 degrees) at 18:00
4/27 The Moon is 0.8 degree southeast of the bright open cluster M35 in Gemini at 23:00; Venus is at greatest brilliancy (magnitude -4.7) at 18:00
4/29 The Moon is 8.3 degrees south of Castor at 10:00; the Moon is 4.6 degrees south of Pollux at 15:00
4/30 The Lunar X (also known as the Werner or Purbach Cross), an X-shaped clair-obscure illumination effect involving various rims and ridges between the craters La Caille, Blanchinus, and Purbach, is predicted to be fully formed at 2:04; the Moon is 1.6 degrees north of M44 at 14:00; First Quarter Moon occurs at 20:38
Christiaan Huygens (1629-1695) was born this month.
Charles Messier discovered the open cluster M50 in Monoceros on April 5, 1772. Charles Messier discovered the spiral galaxy M58 in Virgo on April 15, 1772. Johann Koehler discovered the elliptical galaxies M59 and M60 in Virgo on April 11, 1779. Caroline Herschel discovered C/1790 H1 (Herschel) on April 18, 1790. The first photograph of the Sun was taken on April 2, 1845. The first radar signal was bounced off of the Sun on April 7, 1959. The Hubble Space Telescope was placed in orbit on April 25, 1990. The Compton Gamma Ray Observatory achieved orbit on April 7, 1991.
The Lyrid meteor shower peaks on the night of April 22nd/April 23rd. A typical zenithal hourly rate is about 20 meteors per hour but short outbursts have occurred occasionally. Fireballs are also possible. The radiant lies between the Keystone of Hercules and Lyra. Moonlight will not compromise the 2020 Lyrids. For more on this year’s Lyrids, see the article on page 49 of the April 2020 issue of Sky & Telescope or browse https://earthsky.org...er-guide#lyrids and https://www.amsmeteo...hower-calendar/
Information on passes of the ISS, the USAF’s X-37B, the HST, Starlink, and other satellites can be found at http://www.heavens-above.com/
The Moon is 7.4 days old, is illuminated 43.8%, subtends 31.2', and is located in Gemini at 0:00 UT on April 1st. The Moon is at its greatest northern declination of +23.6 degrees on April 1st and +23.9 degrees on April 29 and its greatest southern declination of -23.8 degrees on April 14th. Longitudinal libration is at a maximum of +7.5 degrees on April 14th and a minimum of -8.0 degrees on April 2nd and -7.2 on April 30th. Latitudinal libration is at a maximum of +6.6 degrees on April 20th and a minimum of -6.5 degrees on April 7th. The Moon is at perigee on April 7th (at a distance of 55.96 Earth-radii) and at apogee on April 20th (at a distance 63.73 Earth-radii). The Moon will be at its closest to the Earth for the year on April 7th. Large tides will occur following the Full Moon on April 8th. New Moon occurs on April 22nd. The Last Quarter Moon, Jupiter, Saturn, and Mars form a 20-degree arc above the south-southeastern horizon on the morning of April 14th. The waning crescent Moon is positioned three degrees south of Saturn, with Jupiter to the upper right and Mars to the left, on the morning of April 15th. On April 26th, the waxing crescent Moon is positioned about four degrees from the third-magnitude star Zeta Tauri. The Moon occults Pluto on April 14th and asteroid 4 Vesta on April 26th from certain parts of the world. Consult http://www.lunar-occ...ota/iotandx.htm for information on occultation events. Visit https://saberdoesthe...does-the-stars/ for tips on spotting extreme crescent Moons and http://www.curtrenz.com/moon06.html for Full Moon data. Consult http://time.unitariu...moon/where.html or download http://www.ap-i.net/avl/en/start for current information on the Moon. See https://svs.gsfc.nasa.gov/4768 for a lunar phase and libration calculator and https://svs.gsfc.nasa.gov/4768 for the Lunar Reconnaissance Orbiter Camera (LROC) Quickmap. Click on https://www.calendar...ndar/2020/april for a lunar phase calendar for this month. Times and dates for the lunar crater light rays predicted to occur this month are available at http://www.lunar-occ...o/rays/rays.htm
The Sun is located in Pisces on April 1. It enters Aries on April 19th.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on April 1: Mercury (0.0, 6.6", 64% illuminated, 1.02 a.u., Aquarius), Venus (-4.5, 25.5", 47% illuminated, 0.65 a.u., Taurus), Mars (+0.8 magnitude, 6.4", 88% illuminated, 1.46 a.u., Capricornus), Jupiter (-2.1 magnitude, 37.0", 99% illuminated, 5.32 a.u., Sagittarius), Saturn (+0.7 magnitude, 16.1", 100% illuminated, 10.30 a.u., Sagittarius), Uranus (+5.9 magnitude, 3.4", 100% illuminated, 20.79 a.u. on April 16th, Aries), Neptune (+7.9 magnitude, 2.2", 100% illuminated, 30.73 a.u. on April 16th, Aquarius), and Pluto (+14.3 magnitude, 0.1", 100% illuminated, 33.98 a.u. on April 16th, Sagittarius).
Venus and Uranus are located in the west in the evening. Mercury and Neptune can be found in the east, and Mars, Jupiter, and Saturn in the southeast in the morning sky.
Mercury brightens from magnitude 0.0 to magnitude -1.2 this month as it decreases in angular (apparent) size from 6.6 arc seconds to 5.1 arc seconds but increases in illumination from 64% to 98%. Mercury has a close conjunction with Neptune on April 3rd. The speediest planet shines at magnitude -0.2 by April 10th and is at its greatest heliocentric latitude south on April 16th. The Moon passes three degrees south of Mercury on April 16th. Observers in the southern hemisphere are favored during the current morning apparition of Mercury.
Brilliant Venus is in one of the very best months of its eight-year cycle of recurring apparitions. During April, Venus grows in brightness to magnitude -4.7 and in angular size to 38.2 arc seconds but drops in illumination from 47% to 26%. On the first day of April, the brightest planet sets approximately four hours after the Sun. On April 3rd, Venus passes one quarter degree southeast of the third-magnitude star Alcyone (Eta Tauri), the brightest star in M45 (the Pleiades). On that day eight years later, Venus will come exceptionally close to the fourth-magnitude star Merope (23 Tauri). The waning gibbous Moon passes six degrees to the south of Venus on April 26th. Venus reaches its greatest illuminated extent, which is the optimum combination of angular size and phase angle, on the evening of April 27th.
Mars increases in brightness from magnitude +0.8 to magnitude +0.4 and grows in angular size from 6.4 arc seconds to 7.6 arc seconds by the end of April. The Red Planet is one degree southeast of Saturn on the morning of April 1st. On April 16th, a waning crescent Moon lies two degrees south of Mars. By the end of the month, Mars is 2.7 degrees due west of the third-magnitude star Deneb Algedi (Delta Capricorni) and rises about three hours before the Sun.
Jupiter increases in brightness to magnitude -2.3 and in apparent diameter from 37.0 to 40.6 arc seconds during April. A very faint Pluto is 45 arc minutes south of Jupiter on April 6th. As the month begins, Jupiter rises just before 1:30 a.m. local daylight time. A waning gibbous Moon passes within two degrees of Jupiter on the morning of April 23rd. The Galilean satellite Ganymede undergoes a shadow transit that ends at 5:52 a.m. EDT (9:52 UT) on April 15th, Europa transits Jupiter starting at 5:17 a.m. EDT (9:17 UT) on April 19th, Io’s shadow crosses Jupiter beginning at 4:43 a.m. EDT (8:43 UT) on April 20th, and Ganymede reappears from occultation shortly after the shadow of Europa begins to transit the planet at 5:18 a.m. EDT (9:18 UT) on April 26th. Data on other Galilean satellite events is available at http://www.skyandtel...watching-tools/ and page 51 of the April 2020 issue of Sky & Telescope. For information on transits of Jupiter’s central meridian by the Great Red Spot, consult https://www.projectp...eve_grs.htm#apr or page 50 of the April 2020 issue of Sky & Telescope.
Saturn rises with Mars at approximately 4:00 a.m. local daylight time on April 1st. As April progresses, Jupiter moves closer to Saturn from the west while Mars heads away from Saturn to the east. The three planets are equally spaced, with Saturn approximately 5.5 degrees from Jupiter and Mars, on April 9th. The Ringed Planet rises before 2:00 a.m. local daylight time, brightens to magnitude +0.6, and subtends 16.9 arc seconds by the end of the month. At midmonth, its rings span 37 arc seconds and are inclined by about 21 degrees. Saturn is two degrees north of the Last Quarter Moon on April 15th. Saturn is at western quadrature on April 21st. Titan, Saturn’s brightest satellite at eighth magnitude, will most likely be the only Saturnian satellite visible in early April due to Saturn’s meager altitude, only some 15 degrees, at the start of morning twilight. Browse http://www.skyandtel...watching-tools/ for information on Saturn’s satellites.
Uranus is in conjunction with the Sun on April 26th and consequently is not visible after the first few days of this month.
Eighth-magnitude Neptune is very low in the east at dawn in late April.
The dwarf planet Pluto is fairly high in the sky in northwestern Sagittarius during morning twilight.
For more on the planets and how to locate them, browse http://www.nakedeyeplanets.com/
Asteroid 4 Vesta shines at magnitude +8.5 as it travels northeastward through Taurus this month. On April 7th, the main belt asteroid passes 3.7 degrees north of the fourth-magnitude star Prima Hyadum (Gamma Tauri) in Melotte 25 (the Hyades); on April 12th, it passes 30 arc minutes north of the fourth-magnitude star Ain (Epsilon Tauri), another member of the Hyades. Four days later it lies several degrees north of the first-magnitude star Aldebaran (Alpha Tauri). Vesta passes somewhat less than two degrees north of the open cluster NGC 1647 on April 23rd. Asteroid 3 Juno (magnitude +9.5) is at opposition in Virgo on April 2nd. It passes one half degree south of the third-magnitude star Minelauva (Delta Virginis) on the nights of April 9th and 10th. A finder chart can be found on page 50 of the April 2020 issue of Sky & Telescope. Asteroids brighter than magnitude +11.0 reaching opposition this month include 6 Hebe (magnitude +10.1) on April 4th, 40 Harmonia (magnitude +9.8) on April 23rd, and 23 Thalia (magnitude +10.0) on April 24th. Click on http://www.asteroido.../2020_04_si.htm for information on asteroid occultations taking place this month. See https://www.curtrenz.../asteroids.html for additional current information on a number of asteroids.
Comet C/2019 Y4 (ATLAS) is the brightest comet visible this month. It can be found in Camelopardalis. See http://www.cometwatc...eye-brightness/ and https://skyandtelesc...ked-eye-object/ for more on this comet, which could brighten to naked-eye visibility by May. Comet C/2017 T2 (PanSTARRS) travels northeastward through Camelopardalis. The eighth-magnitude comet passes several degrees north of the spiral galaxy IC 342 on April 9th. Visit http://cometchasing.skyhound.com/ and http://www.aerith.ne...ly/current.html for information on this month’s comets.
A wealth of current information on solar system celestial bodies is posted at http://www.curtrenz.com/astronomy.html and http://nineplanets.org/
Information on the celestial events transpiring each week can be found at http://astronomy.com/skythisweek and http://www.skyandtel...ky-at-a-glance/
Free star maps for April can be downloaded at http://www.skymaps.com/downloads.html and https://www.telescop...thly-Star-Chart
The fifth-magnitude G-type main-sequence star 61 Virginis - http://www.solstatio...rs/61vir2co.jpg - is a sun-like star at a distance of 28 light years. It hosts three exoplanets and is visible to the naked-eye.
The famous eclipsing variable star Algol (Beta Persei) is at a minimum, decreasing in magnitude from 2.1 to 3.4, on April 3rd, 6th, 9th, 12th, 15th, 17th, 20th, 23rd, 26th, and 29th. Favorable dates for observing Algol at mid-eclipse from the eastern United States occur on April 12th at 12:14 a.m. EDT (4:14 UT) and April 14th at 9:03 p.m. EDT (1:03 UT on April 15th). Consult http://www.skyandtel...watching-tools/ and page 49 of the April 2020 issue of Sky & Telescope for the times of the eclipses. For more on Algol, see http://stars.astro.i.../sow/Algol.html and http://www.solstatio...ars2/algol3.htm
Data on current supernovae can be found at http://www.rochester...y.org/snimages/
Finder charts for the Messier objects and other deep-sky objects are posted at https://freestarcharts.com/messier and https://freestarcharts.com/ngc-ic and http://www.cambridge..._april-june.htm
Telrad finder charts for the Messier Catalog and the SAC’s 110 Best of the NGC are posted at http://www.astro-tom...charts/map1.pdf and http://www.saguaroas...o110BestNGC.pdf respectively.
Information pertaining to observing some of the more prominent Messier galaxies can be found at http://www.cloudynig...ur-astronomers/
Stellarium and Cartes du Ciel are two excellent freeware planetarium programs that are available at http://stellarium.org/ and https://www.ap-i.net/skychart/en/start
Deep-sky object list generators can be found at http://www.virtualcolony.com/sac/ and http://tonightssky.com/MainPage.php
Freeware sky atlases can be downloaded at http://www.deepskywa...-atlas-full.pdf and http://astro.mxd120....ee-star-atlases
Seventy-five binary and multiple stars for April: h4481 (Corvus); Aitken 1774, Gamma Crateris, Jacob 16, Struve 3072, h4456, Burnham 1078 (Crater); h4311, Burnham 219, N Hydrae, h4455, h4465 (Hydra); 31 Leonis, Alpha Leonis (Regulus), h2520, Struve 1417, 39 Leonis, Struve 1421, Gamma Leonis (Algieba), Otto Struve 216, 45 Leonis, Struve 1442, Struve 1447, 49 Leonis, Struve 1482, 54 Leonis, Struve 1506, Chi Leonis, 65 Leonis, Struve 1521, Struve 1527, Struve 1529, Iota Leonis, 81 Leonis, 83 Leonis, Tau Leonis, 88 Leonis, 90 Leonis, Struve 1565, Struve 1566, 93 Leonis, h1201, S Leonis (Leo); h2517, Struve 1405, Struve 1432, 33 Leo Minoris, Struve 1459, 40 Leo Minoris, Struve 1492 (Leo Minor); Struve 1401, Struve 1441, Struve 1456, Struve 1464, 35 Sextantis, 40 Sextantis, 41 Sextantis (Sextans); Struve 1402, Struve 1415, Struve 1427, Struve 1462, Struve 1486, Struve 1495, Struve 1510, Struve 1520, Xi Ursae Majoris, Nu Ursae Majoris, Struve 1541, 57 Ursae Majoris, Struve 1544, Struve 1553, Struve 1561, Struve 1563, 65 Ursae Majoris, Otto Struve 241 (Ursa Major)
Notable carbon star for April: V Hydrae (Hydra)
One hundred deep-sky objects for April: NGC 4024, NGC 4027 (Corvus); NGC 3511, NGC 3513, NGC 3672, NGC 3887, NGC 3892, NGC 3955, NGC 3962, NGC 3981 (Crater); NGC 3091, NGC 3109, NGC 3145, NGC 3203, NGC 3242, NGC 3309, NGC 3585, NGC 3621, NGC 3717, NGC 3904, NGC 3936 (Hydra); M65, M66, M95, M96, M105, NGC 3098, NGC 3162, NGC 3177, NGC 3185, NGC 3190, NGC 3226, NGC 3227, NGC 3300, NGC 3346, NGC 3367, NGC 3377, NGC 3384, NGC 3389, NGC 3412, NGC 3437, NGC 3489, NGC 3495, NGC 3507, NGC 3521, NGC 3593, NGC 3607, NGC 3608, NGC 3626, NGC 3628, NGC 3630, NGC 3640, NGC 3646, NGC 3655, NGC 3681, NGC 3684, NGC 3686, NGC 3691, NGC 3810, NGC 3842, NGC 3872, NGC 3900, NGC 4008 (Leo); NGC 3245, NGC 3254, NGC 3277, NGC 3294, NGC 3344, NGC 3414, NGC 3432, NGC 3486, NGC 3504 (Leo Minor); NGC 2990, NGC 3044, NGC 3055, NGC 3115, NGC 3156, NGC 3166, NGC 3169, NGC 3246, NGC 3423 (Sextans); IC 750, M97, M108, M109, NGC 3079, NGC 3184, NGC 3198, NGC 3310, NGC 3359, NGC 3610, NGC 3665, NGC 3675, NGC 3738, NGC 3877, NGC 3898, NGC 3941, NGC 3953, NGC 3998, NGC 4026 (Ursa Major)
Top ten deep-sky objects for April: M65, M66, M95, M96, M97, M105, M108, NGC 3115, NGC 3242, NGC 3628
Top ten binocular deep-sky objects for April: M65, M66, M95, M96, M97, M105, M108, M109, NGC 3115, NGC 3242
Challenge deep-sky object for April: Leo I (Leo)
The objects listed above are located between 10:00 and 12:00 hours of right ascension. | 0.920281 | 3.376052 |
Harold Klein was a long-time exobiology researcher, and a champion for the field of astrobiology at NASA Ames Research Center. Klein's initial interest in exobiology was sparked at Berkeley, when one of his graduate students regaled him with glowing reports on a series of talks by astronomer Carl Sagan on the prospects for extraterrestrial life. After moving to Brandeis University, Klein researched the possible biochemical processes that might be displayed by life on other planets. Informed by a colleague that Ames was looking for someone to head its new Exobiology division, Klein decided to take the post. He continued such as Cyril Ponnamperuma, who synthesized organic molecules under conditions simulating primitive Earth. About a year after he joined Ames, Klein was promoted by Smith DeFrance to lead the Life Sciences Division.
In 1985, Klein attended the Woods Hole Conference on the scientific aspects of exploring Mars. At Woods Hole, Klein and his fellow exobiologists devised a strong case for sending a spacecraft to investigate the prospects for life, either current or ancient, on the Red Planet. The biologists' enthusiasm for such a mission coincided neatly with the Mars exploration proposals of NASA planetary scientists, and in 1969 the Viking project was approved by Congress. Klein was soon named Biology Team Leader for the Viking project and placed in charge of hammering out a consensus among the many possible and conflicting proposals for detecting life on Mars; finding the best compromise between the project engineers who wanted to keep the spacecraft as lightweight and simple as possible, and the scientists who were loath to exclude any of their experimental instruments from Viking and hence lose a possible chance for finding life; and serving as media spokesperson on Viking's biological objectives.
The first Viking lander touched down in Chryse Planitia, Mars on July 20, 1976. Although the preliminary results returned by the biology experiments were tantalizing, they were far from conclusive, much to the disappointment of the press and the public. Ever the careful scientist, however, Klein resisted the extreme media pressure to make some kind of definitive pronouncement about the question of life on Mars, maintaining that the Viking results were more likely due to chemical rather than biological activity. It was not what people wanted to hear, but scientific truth was more important to Klein than pleasing the media. In fact, he was rather disappointed that the press and public seemed to disregard the "miracle," as he put it, of landing such a complex craft on such a distant planet to obtain such important data. But Klein certainly appreciated Viking's significance, and was a major factor in the mission's success. Many of Klein's fellow scientists maintain that without his energetic and creative management of Viking's biology team, there would have been no mission at all.
The Viking mission is only the most publicly prominent example of Dr. Klein's contributions to science and to NASA Ames. Throughout his career, he was the primary force that established Ames' reputation as the key NASA institution for the study of astrobiology in all its various facets, including exobiology, gravitational biology, and biomedicine (with the initiation of Space Shuttle experiments in these areas), and recruited a brilliant staff of scientists for the Life Sciences Division. More than any other individual, Harold Klein is the man who build the foundation upon which rests Ames' current leadership in astrobiology. For this, he was inducted into the NASA Ames Hall of Fame. He passed away in 2001. | 0.883419 | 3.009862 |
While orbiting Saturn for the last six years, NASA’s Cassini spacecraft has kept a close eye on the collisions and disturbances in the gas giant’s rings. They provide the only nearby natural laboratory for scientists to see the processes that must have occurred in our early solar system, as planets and moons coalesced out of disks of debris.
New images from Cassini show icy particles in Saturn’s F ring clumping into giant snowballs as the moon Prometheus makes multiple swings by the ring. The gravitational pull of the moon sloshes ring material around, creating wake channels that trigger the formation of objects as large as 20 kilometers (12 miles) in diameter.
“Scientists have never seen objects actually form before,” said Carl Murray, a Cassini imaging team member based at Queen Mary, University of London. “We now have direct evidence of that process and the rowdy dance between the moons and bits of space debris.”
Murray discussed the findings today (July 20, 2010) at the Committee on Space Research meeting in Bremen, Germany, and they are published online by the journal Astrophysical Journal Letters on July 14, 2010. A new animation based on imaging data shows how one of the moons interacts with the F ring and creates dense, sticky areas of ring material.
Saturn's thin, kinky F ring was discovered by NASA’s Pioneer 11 spacecraft in 1979. Prometheus and Pandora, the small “shepherding” moons on either side of the F ring, were discovered a year later by NASA’s Voyager 1. In the years since, the F ring has rarely looked the same twice, and scientists have been watching the impish behavior of the two shepherding moons for clues.
Prometheus, the larger and closer to Saturn of the two moons, appears to be the primary source of the disturbances. At its longest, the potato-shaped moon is 148 kilometers (92 miles) across. It cruises around Saturn at a speed slightly greater than the speed of the much smaller F ring particles, but in an orbit that is just offset. As a result of its faster motion, Prometheus laps the F ring particles and stirs up particles in the same segment once in about every 68 days.
“Some of these objects will get ripped apart the next time Prometheus whips around,” Murray said. “But some escape. Every time they survive an encounter, they can grow and become more and more stable.”
Cassini scientists using the ultraviolet imaging spectrograph previously detected thickened blobs near the F ring by noting when starlight was partially blocked. These objects may be related to the clumps seen by Murray and colleagues.
The newly-found F ring objects appear dense enough to have what scientists call “self-gravity.” That means they can attract more particles to themselves and snowball in size as ring particles bounce around in Prometheus’s wake, Murray said. The objects could be about as dense as Prometheus, though only about one-fourteenth as dense as Earth.
What gives the F ring snowballs a particularly good chance of survival is their special location in the Saturn system. The F ring resides at a balancing point between the tidal force of Saturn trying to break objects apart and self-gravity pulling objects together. One current theory suggests that the F ring may be only a million years old, but gets replenished every few million years by moonlets drifting outward from the main rings. However, the giant snowballs that form and break up probably have lifetimes of only a few months.
The new findings could also help explain the origin of a mysterious object about 5 to 10 kilometers (3 to 6 miles) in diameter that Cassini scientists spotted in 2004 and have provisionally dubbed S/2004 S 6. This object occasionally bumps into the F ring and produces jets of debris.
“The new analysis fills in some blanks in our solar system’s history, giving us clues about how it transformed from floating bits of dust to dense bodies,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “The F ring peels back some of the mystery and continues to surprise us.”
The late Kevin Beurle was made the honorary first author on this paper because of his contributions in developing software and designing observation sequences for this research. He died in 2009.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.
Jia-Rui C. Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
Joe Mason 720-974-5859
Space Science Institute, Boulder, Colo.
Simon Levey 011-44-20-7882-7454
Queen Mary, University of London | 0.80646 | 3.966898 |
PNG images: Star
A star is a luminous sphere of plasma held together by its own gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye from Earth during the night, appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth. Historically, the most prominent stars were grouped into constellations and asterisms, the brightest of which gained proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. However, most of the stars in the Universe, including all stars outside our galaxy, the Milky Way, are invisible to the naked eye from Earth. Indeed, most are invisible from Earth even through the most powerful telescopes.
Star PNG images
Did you know
For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen into helium in its core, releasing energy that traverses the star's interior and then radiates into outer space. Almost all naturally occurring elements heavier than helium are created by stellar nucleosynthesis during the star's lifetime, and for some stars by supernova nucleosynthesis when it explodes. Near the end of its life, a star can also contain degenerate matter. Astronomers can determine the mass, age, metallicity (chemical composition), and many other properties of a star by observing its motion through space, its luminosity, and spectrum respectively. The total mass of a star is the main factor that determines its evolution and eventual fate. Other characteristics of a star, including diameter and temperature, change over its life, while the star's environment affects its rotation and movement. A plot of the temperature of many stars against their luminosities produces a plot known as a Hertzsprung–Russell diagram (H–R diagram). Plotting a particular star on that diagram allows the age and evolutionary state of that star to be determined.
A star's life begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. When the stellar core is sufficiently dense, hydrogen becomes steadily converted into helium through nuclear fusion, releasing energy in the process. The remainder of the star's interior carries energy away from the core through a combination of radiative and convective heat transfer processes. The star's internal pressure prevents it from collapsing further under its own gravity. A star with mass greater than 0.4 times the Sun's will expand to become a red giant when the hydrogen fuel in its core is exhausted. In some cases, it will fuse heavier elements at the core or in shells around the core. As the star expands it throws a part of its mass, enriched with those heavier elements, into the interstellar environment, to be recycled later as new stars. Meanwhile, the core becomes a stellar remnant: a white dwarf, a neutron star, or if it is sufficiently massive a black hole.
Binary and multi-star systems consist of two or more stars that are gravitationally bound and generally move around each other in stable orbits. When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution. Stars can form part of a much larger gravitationally bound structure, such as a star cluster or a galaxy. | 0.884151 | 3.868437 |
Our unique program blends course work with analysis alternatives and supplies college students access to professional-quality telescopes, instrumentation and computers. Most of those stars will not be visible from Earth Virtually every thing that we will see in the sky belongs to the Milky Manner Galaxy. Both the Milky Method and one in all our nearest galaxy neighbors, the Andromeda Galaxy , are spiral galaxies. College students that graduate with a level at this stage can typically find assistant researcher roles inside astronomy software departments, telescope operations and observatories.
Life Beyond the Earth This chapter covers: life zones (liveable zones), kinds of stars to deal with within the search for suitable planets, traits of life, evolution by pure choice, working definitions of life, the kind of planet the place we predict life would doubtless come up, bio-markers in exoplanet spectra, and at last the frequencies we use in the Seek for Further-Terrestrial Intelligence (S.E.T.I.).
The basic telescopes normally are available in reflecting and refracting sorts but reflecting types are less costly and permit you to view galaxies. The examine of astronomy typically begins with an curiosity within the constellations which are seen within the night time sky.
Astronomy is often (not all the time) about very concrete, observable issues, whereas cosmology usually involves giant-scale properties of the universe and esoteric, invisible and generally purely theoretical things like string theory, dark matter and dark energy, and the notion of multiple universes.
Perhaps one of the oldest sciences, we’ve got record of people finding out astronomy as far back as Historical Mesopotamia Later civilizations such because the Greeks, Romans, and Mayans also studied astronomy. The Geminids meteor shower peaks on the mornings of December 13 and 14, 2018 – however if you search for any time there’s a clear night time sky up till December 17, you may simply catch a glimpse of a Geminid meteor.
Our solar system consists of the sun, planets, dwarf planets (or plutoids), moons, an asteroid belt, comets, meteors, and different objects. But the variety of constellations and stars we’re in a position to see each year is actually a very small number out of the plethora of stars in the sky.
In that distant time Humankind perceived within the sky the presence of gods and tried to breed on earth the house of those gods. There are different smaller object that orbit the Solar, together with asteroids , comets , meteoroids and dwarf planets. The Sun and Stellar Construction This chapter covers: The Sun, interiors of stars, and nuclear fusion, neutrinos, the solar neutrino downside, and helioseismology. | 0.925949 | 3.188166 |
The astronomer and mathematician Johannes Kepler was born on December 27, 1571 in Weil (Germany) and died on November 15, 1630 in Regensburg. Having changed schools several times for various reasons, he began to study at the Swabian university in Tübingen in 1589, where his main teacher was the mathematician and astronomer Michael Mästlin, who introduced him to the Copernican heliocentric idea of the universe.
In August 1591 Kepler received his master's degree. Subsequently he studied theology more intensively, which he had been introduced to by the polemic Stephan Gerlach and the exegete Matthias Hafenreffer. When he was in his third year of reading theology, Kepler was called to the university of Graz, where he taught from March 1594. In 1595 to 1599 he produced 5 calendars alongside his teaching career, the production of which was one of his main tasks as Mathematicus. His apt predictions for 1594 (cold winter, invasion of the Turks) soon turned Johannes Kepler into a famous astrologist.
In 1596 he published his "Mysterium cosmographicum", which combined the Copernican system with five platonic bodies in a spectacular way. Tycho Brahe, who had become aware of him because of this piece, brought him to Prague in 1600 under Kaiser Rudolph II. In the fall of 1604 he published "Silvae chronologicae" in Prague, in 1605 "De Stella nova in pede Serpentarii" ("On the New Star in Ophiuchus's Foot") and in 1607 a text on a comet that appeared that year.
"Astronomia nova", which includes Kepler's first and second law of planetary motion, formed the essence of his work. In it he was the first to present a focal point equation for conic section. In 1618 Johannes Kepler formed his third law of planetary motion, in which he discovered the interdependence between orbital period and the mean distance of planets from the sun. This third law can be found in "Harmonices mundi" (1619). In his book "De stella martis" (1609), Johannes Kepler dealt with the gravitational force working between earth and moon and proved the influence of the moon on the tides.
In 1611 Kepler invented an astronomical telescope, named the Kepler-telescope in his honor. In this context he also introduced terms like "prism", "lens" and "meniscus".
More on this issue can be found in his "Dioptrice", which deals with geometrical optics. It is furthermore worth mentioning, that Kepler outlined a comprehensive and correct theory on the benefits of spectacles and studied the passage of light through refractive media.
Johannes Kepler determined the astronomical refraction of rays and calculated a formula for it, which was completed geometrically by J. D. Cassini in 1661. In 1627, after a long delay in printing, his "Tabulae Rudolphinae" were published.
From 1601 Kepler had already worked on the design of tables containing solar, lunar and planetary locations. Thanks to the logarithms, newly discovered by Napier in 1614, he finally managed to execute the complicated calculations for his "Tabulae", which formed the basis of numerous astronomical calculations during the next 200 years. His contribution to the development of modern infinitesimal calculus is based on his most important piece on mathematics, "Nova stereometria doliorum vinariorum" (1615), in which he calculated areas and volumes with the help of indivisibles (his so-called "Keplersche Fassregel").
In 1628 he entered into the service of A. von Wallenstein as a mathematician and moved to Sagan (Silesia). His last work "Somnium seu astronomia lunaris" (1634) is an utopic description of the life of lunar creatures. | 0.840383 | 3.607144 |
An exoplanet is confirmed for the first time using an instrument built by the Calar Alto Observatory, Almería, Spain. It is the first planet orbiting a giant star whose confirmation is beyond any doubt.
The planetary nature of an object orbiting the giant star KIC 8219268 has been confirmed by using the radial velocity technique and the Calar Alto Fiber-fed Echelle spectrograph (CAFE), the first instrument built by the Spanish-German Astronomical Center, in Almería, Spain. Researchers from the Center of Astrobiology (CAB, INTA-CSIC), the Max-Planck Institut für Astronomy (MPIA, MPG), Centro de Astrofisica e Departamento de Física e Astronomia (Universidade do Porto), Instituto de Astronomía (UNAM) and from Calar Alto (CAHA), in Spain, Germany, Portugal and Mexico have applied this well understood methodology and have obtained a mass similar to Jupiter. The planet, named Kepler-91b, is located extremely close to the star. This is the first planet ever confirmed based on data acquired from Calar Alto Observatory.
The star KIC 8219268 was identified by the satellite Kepler and identified as potentially harboring a planet with a orbital period of 6.246580 days, due to small periodical dims in the Kepler light curve. As a planet host candidate, it was named Kepler Object of Interest 2133. By analyzing the exquisite data, our team inferred the presence of a planet with a mass slightly lighter than Jupiter, orbiting very nearby the central star, at about 2.32 stellar radii. This was achieved by analyzing the light curve modulations due to the presence of a planet, the transit dim provoked by the tiny stellar occultation by the planet, and asteroseismic signals due to the oscillations in the star itself. Thus, the Kepler team assigned the name Kepler-91b for the planet.
We concluded that Kepler-91b could be the previous stage of the planet engulfment, and it would be the closest planet to a giant star. With a slightly elliptical orbit, the central star should subtend an angle of 48 degrees at the closest approach, covering around 10% of the sky as seen from the planet. In addition, the planetary atmosphere seems to be inflated probably due to the high stellar irradiation.
Quasi-simultaneous works rejected the planetary nature of Kepler-91b, based on the Kepler light curve analysis and its self-luminous property. Thus, two different groups claimed that is was just an eclipsing binary with another star nearby, which might or might not be physically connected to the first two stars.
The light curve for Kepler-91, derived from the Kepler data. The solid green line shows our solution based on the effect of the planet. The mass of the planet, among other parameters, is derived from the data and the modeling
To solve this dichotomy in the interpretation, which leads to totally opposed conclusions, we have collected high-resolution spectroscopy with the Calar Alto Fiber-fed Echelle spectrograph (CAFE). It has been the first instrument ever built at the observatory and it works with the 2.2m telescope under very strict and controlled conditions. The radial velocity technique was used to detect a planet for the first time in 1995 and since then 573 planets in 429 planetary systems have been confirmed using this method, making it the reference in the exoplanetary studies. Our data independently confirm the presence of a planet with a mass of 1.09 Jupiter masses, a value fully compatible with our previous estimate based on the light curve modulations. Thus, a spin-off result is the validation of the light curve modulation as a bona-fide planetary confirmation technique. The paper describing these results, led by Jorge Lillo-Box and David Barrado, has been accepted by Astronomy & Astrophysics Letters.
A Spanish-German consortium is building a new state-of-the-art optical and near-infrared spectrograph, called CARMENES. Its goal is to hunt for rocky planets orbiting around cool stars. It is expected to see first light in late 2015 and it will work at the CAHA 3.5m telescope. CAFE at the 2.2m telescope has become a stepping stone for the techniques and observing strategies which will be applied to CARMENES, bridges the gaps during these months until CARMENES arrives and also is covering a unique niche in the complex ecology of exoplanets.
J. Lillo-Box (Astrophysics Department, Center of Astrobiology, CSIC-INTA, Spain); D. Barrado (Astrophysics Department, Center of Astrobiology, CSIC-INTA, Spain); T. Henning (Max Planck Institut für Astronomie, Germany); L. Mancini (Max Planck Institut für Astronomie, Germany); C. Ciceri (Max Planck Institut für Astronomie, Germany); P. Figueira (Instituto de Astronomia e Ciências do Espaço/Centro de Astrofísica, Universidade do Porto, Portugal); N.C. Santos (Instituto de Astronomia e Ciências do Espaço/Centro de Astrofísica, Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Portugal); J. Aceituno (Centro Astronómico Hispano-Alemán, Calar Alto Observatory, Spain); and S. Sánchez (Instituto de Astronomía,Universidad Nacional Autonóma, México) | 0.87834 | 3.940009 |
Lisbon/Leiden – There are clusters of red-and-dead members of galaxies that used to be stars in the past, and have disintegrated or died. Lately, astronomers – David Sobral, at the University of Lisbon and Andra Stroe hailing from Leiden Observatory, observed that cosmic tsunamis can add life to dormant, inactive or dead galaxies in this universe.
The duo have come together and conducted a detailed research on the concepts pertaining to cosmic tsunamis. The study was published in the monthly version of Royal Astronomical Society journal.
This phenomenon has been in vogue for billions of years. Clusters of galaxies grow, expand substantially and merge with another. When two such galaxy clusters collide, loads of energy is generated massively. It leads to the birth of new-found stars, besides giving new life to a myriad of dormant galaxies. This concept is a cosmic tsunami, which went unnoticed till date.
Modes of observations
The duo researchers have come across merging galaxy clusters in outer space – CIZA J2242.8+5301, dubbed as “Sausage”, at a distance of 2.3 billion light-years, from the surface of the earth. The cosmic shock waves resulted in the formation of ‘alive’ stars.
Issac Newton Telescopes and William Herschel Telescopes present in La Palma and the Keck and Subaru Telescopes present in Hawaii were used to view the phenomenon.
In a statement, Stroe mentioned that previously, there was a common belief that galaxies don’t have many roles to play. He added that galaxies played the leading roles.
How did the star get reawakened?
Once-dead Sausage cluster are on the verge of becoming ‘alive’ at a tremendous pace. The collision happened such that the galaxies came close at 9 million kilometers for every hour.
There was turbulence in prevalent galactic gas. The galaxies witnessed an avalanche breakdown; cold and dense gas got formed, and thus ‘Sausage’ got reawakened. | 0.868621 | 3.476491 |
This is an image of Venus.
Click on image for full size
The Cooling of Venus
The following may be the history of Venus.
- Venus formed about 4 Billion Years ago.
- at the conclusion of forming it continued to be bombarded with leftover material. Many planets still bear the remains of this activity by showing many craters on the surface. Activity on the surface can act to change the craters.
- Venus warmed from inside, and separated into layers. Because Venus is close to the sun, the atmosphere formed differently than did the Earth's, as sugggested by the Goldilocks idea.
- After that, Venus started cooling down. The crust began to thicken, just like jello hardens when it is being made. The hardening crust prevented continental drift. This also prevented the recycling of the atmosphere.
- Despite the thick crust, surface activity, including volcanism, may continue to this day as Venus continues to cool.
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A new estimate of Saturn’s rotation rate reveals days on the gas giant are five minutes shorter than previously believed — and that Saturn’s atmosphere has much in common with that of its planetary neighbor, Jupiter.
The new results appear today in the journal Nature.
(Image caption: Saturn as photographed by Cassini-Huygens. Credit: NASA)
For planets with solid surfaces, the spin rate can simply be determined by tracking the motion of landforms as they rotate across the surface.
Like the rocky planets, gas giant planets such as Jupiter and Saturn spin on their axes with well defined rotation periods. But, with no solid surface features to track, measuring the rotation period of a gas giant is a challenge. The approach that has worked for Jupiter, Uranus and Neptune — using the rotation of the planet’s magnetic field to infer its bulk rotation — gives results for Saturn that change with time, and implies a pattern of atmospheric winds that is very different from that seen on Jupiter.
Peter Read, of the University of Oxford in the UK, and his colleagues used atmospheric dynamics on Saturn to derive a rotation rate that is slightly faster than those inferred from magnetic measurements. When Saturn’s atmospheric winds are viewed relative to this new interior reference frame, they show a pattern of alternating eastward and westward jets similar to the pattern seen on Jupiter.
“This shifted reference frame is consistent with a pattern of alternating jets on Saturn that is more symmetrical between eastward and westward flow,”Read and his co-authors write. “This suggests that Saturn’s winds are much more like those of Jupiter than hitherto believed.”
The authors propose a new rotation rate of 10 hours and 34 minutes, as opposed to the previous estimate of 10 hours 39 minutes. The new rate also sheds light on Saturn’s interior structure, including its density and the mass of a possible rocky core. And it bears on the latitudinal gradient of temperatures below the clouds.
In a related editorial, Adam Showman of the University of Arizona in Tucson writes that there remain key differences between the atmospheres of Saturn and Jupiter: “Saturn’s winds are stronger than Jupiter’s, its banded cloud patterns and populations of hurricane-like vortices differ considerably, and its magnetic field, which is almost symmetrical about its axis — a puzzle in its own right — contrasts with Jupiter’s tilted dipole,” he notes. “These contrasts indicate that the planets are cousins rather than twins, whose intriguing mix of similarities as well as differences will keep planetary scientists engaged for years to come.”
Second image caption: An image of Saturn from NASA’s Cassini spacecraft, clearly showing the ‘geographic’ South Pole of the planet (at the center of the circle of clouds, lower left). The bulk rotation of the planet is around an axis passing through the South Pole and Saturn’s clouds (of ammonia ice) are organized into dark ‘belts’ and light ‘zones’ that are generally aligned with lines of latitude, indicating the influence of the planet’s rotation on its meteorology. | 0.847348 | 3.983455 |
In a novel application of space-based atmospheric measurements, Atmospheric and Environmental Research (AER) of Lexington, Massachusetts, in collaboration with GeoOptics of Pasadena, CA, is investigating the use of radio occultation (RO) measurements to improve severe weather forecasting. Pairing state-of-the-art, high-fidelity weather models with the rapidly evolving technology of miniaturized satellites in a scientific investigation is unique and new. So, the results of AER's study are not only intriguing from a science/discovery point of view, but compelling also, with the very distinct possibility of becoming a reality in the next few years.
The challenges of severe weather forecasting
Detailed severe weather forecasting continues to be a vexing problem for meteorologists. There are simply not enough measurements of atmospheric temperature, moisture and pressure to start up, or initialize, today's detailed weather models accurately. The start-up problem for such models is "underdetermined", in mathematical terms.
Applying established techniques in a new, unique way
Radio occultation is a well-established technique today for measuring planetary atmospheres, first used in the 1960's to probe the atmosphere of Venus from Earth. The technique involves two orbiting satellites exchanging radio signals along a straight line that passes through the edge, or limb, of Earth's atmosphere. The signals that pass from one to the other are called "signals of opportunity", because they already exist as part of the Global Navigation Satellite System (GNSS). As the two satellites move with respect to each other, the straight line between them either cuts down further into the atmosphere (known as a "setting occultation") or moves from Earth's surface up and out of the top of the atmosphere (known as a "rising occultation"). The Earth occludes or blocks the two satellites from seeing one another at the beginning or end of an observing sequence, so these measurements are referred to as "occultations". Subtle changes are induced in the radio signals passed between the two satellites by that portion of the atmosphere through which the signals pass. Those signal changes contain markers for atmospheric temperature and water vapor. In the last decade, a partnership between US and Taiwan space agencies has flown a 6-satellite constellation to measure Earth's atmosphere using radio occultations, the COSMIC/FORMOSAT-6 mission. Measurements made by the COSMIC mission have proven to be invaluable to meteorologists world-wide. The six orbiting COSMIC satellites currently gather about 1,400 vertical occultation profiles every day globally. The COSMIC follow-on constellation of radio occultation satellites, COSMIC-2, when fully deployed (12 satellites) will produce 8,000 - 10,000 global profiles/day.
Over the next few years, GeoOptics expects to launch a constellation of miniature radio occultation satellites that will yield about 50,000 vertical occultation profiles every day globally, the front end of their CICERO constellation. This significant increase over COSMIC and COSMIC-2 observation yields should produce measurable improvements in global weather forecast models, but perhaps only very modest improvements in small-scale regional weather models where the sampling requirements in space and time are much more stringent.
In AER's study, we are considering the potential impact of constellations of radio occultation satellites on weather forecasting that are very much larger than COSMIC, COSMIC-2 or the initial CICERO deployment, comprised of hundreds to a thousand orbiting/measuring units instead of six, twelve or twenty-four. The CICERO constellations AER is investigating can yield up to 2.5 million vertical occultation profiles every day globally. For comparison purposes, the COSMIC mission gathers about 1 vertical radio occultation profile over the state of Oklahoma every other day. A future constellation that yields 2.5 million vertical profiles globally means 35-50 vertical profiles over the state of Oklahoma every hour.
Because these are potential future satellite constellations, actual observations from these constellations don't exist for testing. So we conduct our study "in simulation", using a scientific method known as Observing System Simulation Experiments, or OSSEs. In an OSSE, the true atmospheric state is calculated by a high-fidelity weather model, and experiments using simulated observations employ a lower resolution model. The experiments fuse simulated observations with a best guess atmosphere in a repeated cycle every hour. We use a data fusion technique that relies on an ensemble of forecasts to get the best estimate of uncertainty in our first guess, or a priori, atmospheric states. To test the impact of the new observations, a "Control" data assimilation experiment is generated. A Control experiment is a baseline result, without any of the new observation type — radio occultations in our case. Further experiments that add varying amounts of the new observation type to the control set of observations provide a way to gauge the impact as more and more of the new observation type are used.
Significant results, plus more studies planned
In our OSSE, we chose a severe weather case in Oklahoma that produced an EF3 tornado and flash flooding in the Oklahoma City metro area, late in the afternoon and early evening of May 31, 2013.
Figures 1-3 show snapshots of a key ingredient for severe weather, water vapor in the lower part of the troposphere, from different treatments in our OSSE. All are valid at the same time, about 12 noon local time, May 31, 2013 (i.e., 4-5 hours before severe weather impacted Oklahoma City), and at the same level in the atmosphere, about 4,000 feet above ground level. Figure 1 shows water vapor from the Nature Run (high-fidelity; our OSSE's "truth"). Figures 2 & 3 compare the effects of using conventional weather observations versus conventional weather observations plus CICERO radio occultation profiles. The data fusion experiment that includes the CICERO observations (Fig. 3) produces a water vapor analysis that is very much closer to the Nature Run snapshot (Fig. 1) than the data fusion experiment that uses only conventional weather observations (Fig. 2). These results show that CICERO data has significant potential to produce more accurate analyses in severe weather environments, and therefore, better characterize the environment for severe weather convective initiation. More accurate 3D analyses of temperature, water vapor and pressure in the lower troposphere is critical to improved severe weather forecasts. But the proof awaits in the forecasts started from these analyses.
Our severe weather OSSE study will continue to measure the effects of CICERO data on subsequent severe weather forecasts. We are using updraft helicity (UH) and accumulated precipitation to verify the forecasts against the Nature Run. Also, by examining the effects over a range of constellation sizes, 15,000 - 2,500,000 global profiles/day, we can perhaps find an inflection point in the impact of these data. That is, is there a point at which the cost of adding more orbiting satellites does not produce a correspondingly valuable improvement in severe weather forecasts?
Figure 1. "Nature Run" atmospheric water vapor at about 4,000 feet above the ground. The yellow-to-red color scale (bottom of figure) indicates how much water vapor is present, i.e., yellow is dry and red is moist. This realization of atmosphere moisture during an Oklahoma severe weather outbreak in May 2013 is the yardstick against which our assimilation experiments are compared for realism. It has a horizontal resolving power of about 1 1/4 mile (i.e., 2 km).
Figure 2. Atmospheric water vapor analysis using conventional observing system. Valid time, vertical level and color scale are the same as in Figure 1. Note that the data fusion experiments use a bigger grid than the Nature Run (Figure 1) with a horizontal resolving power of about 11 miles (i.e., 18 km).
Figure 3. Atmospheric water vapor analysis using conventional observing system + CICERO radio occultation observations. The distribution of water vapor in this analysis is much closer to the Nature Run (Fig. 1) in pattern and magnitude than the Control result (Fig. 2). | 0.869773 | 3.935299 |
The explosion likely occurred within a dense shell of matter shed by a companion star.
The supernova SN 2006gy was the brightest and most energetic stellar explosion ever recorded when it was discovered in 2006. At top, an artist’s illustration shows how SN 2006gy may have appeared at a close distance. The bottom left panel is an infrared image by the Lick Observatory of NGC 1260, the galaxy containing SN 2006gy. The panel to the right shows an X-ray image of the same field of view captured by NASA’s Chandra X-ray Observatory.(Image: © X-ray: NASA/CXC/UC Berkeley/N.Smith et al.; IR: Lick/UC Berkeley/J.Bloom & C.Hansen)
One of the most luminous stellar explosions ever detected may now be explained. It came from the detonation of a dead star within the dense shell of matter ejected from that sun’s companion star, a new study suggests.
Supernovas are explosions that can happen when stars die, either after the stars burn all their fuel or gain a sudden influx of new fuel. These outbursts can briefly outshine all of the other suns in these stars’ galaxies, making them visible from halfway across the universe.ADVERTISING
Recently, scientists discovered a rare class of exploding star known as superluminous supernovas. These explosions are up to 100 times brighter than regular supernovas but account for less than 0.1% of all supernovas.
Much remains unknown about what powers superluminous supernovas; they release far more energy than any standard mechanism for powering supernovas can explain. To learn more about what drives these extraordinary explosions, scientists focused on SN 2006gy, one of the first known superluminous supernovas. SN 2006gy occurred in a galaxy 240 million light-years away and was the brightest and most energetic supernova ever recorded when it was discovered, in 2006.
A little more than a year after SN 2006gy was spotted, researchers detected an unusual spectrum of light from the supernova. Now, scientists have deduced that this light came from an envelope of iron around the supernova, revealing clues as to what might have caused the explosion.
The researchers developed computer models of what kind of light would be generated by envelopes of iron with various masses, temperatures, clumping patterns and other properties. They found that the wavelengths and energies of light seen from SN 2006gy likely came from a huge amount of iron — “over a third of the sun’s mass” — expanding at about 3,355 mph (5,400 km/h), study lead author Anders Jerkstrand, an astrophysicist at the Max Planck Institute for Astrophysics in Garching, Germany, told Space.com.
Initial analysis of SN 2006gy suggested that the supernova happened after a giant star ran out of fuel, with the star’s core then collapsing under its own weight into an extraordinarily dense nugget in a fraction of a second and rebounding with a giant blast outward. However, such a “core-collapse” supernova likely would not have generated an iron envelope with the kind of mass and expansion rate that the new study calculated.
Instead, a scenario consistent with the new findings suggests that SN 2006gy was a so-called Type Ia supernova, which occurs when one star pours enough fuel onto a dead star known as a white dwarf to trigger an extraordinary nuclear explosion. (White dwarfs are the superdense, Earth-size cores of stars that exhausted all their fuel and shed their outer layers without catastrophic explosions.)
Specifically, the scenario called for a white dwarf in a close binary orbit with a hydrogen-rich companion star. “Such systems are in fact well known and common — the so-called cataclysmic variables, of which we know of several hundred,” Jerkstrand said.Click here for more Space.com videos…‘We Don’t Planet’ Episode 12: Type-1a SupernovaeVolume 0% PLAY SOUND
When such a companion star gets old, it swells, trapping the white dwarf in its expanding shell. The resulting friction “causes the white dwarf to spiral towards the center, and at the same time, the envelope material is ejected,” Jerkstrand said.
Normally in such binary systems, the white dwarf may spend millions or billions of years spiraling toward the center of its companion before exploding as a Type Ia supernova, Jerkstrand said. However, with SN 2006gy, the researchers suspected that the white dwarf may have exploded “within only about a century since the initiation of the inspiral phase,” he said.
This supernova then slammed into the dense shell of material ejected from the white dwarf’s companion star, which was still relatively nearby. Striking this envelope would have been “like hitting a brick wall, and most of the motion energy of the supernova was transformed into light in this collision,” explaining why SN 2006gy was so bright, Jerkstrand said.
A few other superluminous supernovas share similar properties with SN 2006gy. That similarity suggests that these supernovas also share the same underlying mechanics, the researchers said.
Future research can investigate how binary systems that might give rise to such superluminous supernovas may form. Researchers could also look into what exactly might trigger a Type Ia supernova from white dwarfs in such systems only a century or so after they spiral toward the centers of their companions.
“Did the supernova occur as the inspiraling white dwarf encountered another compact object
at the center of the companion, or did it accrete matter until it became too massive and exploded?” Jerkstrand said.
The scientists detailed their findings in the Jan. 24 issue of the journal Science. | 0.806892 | 4.067835 |
It was on the first day of the new year that the announcement was made, almost simultaneously from three observatories, that the motion of the planet Neptune, the outermost of all the planets that wheel about the sun, had become very erratic. Ogilvy had already called attention to a suspected retardation in its velocity in December. Such a piece of news was scarcely calculated to interest a world the greater portion of whose inhabitants were unaware of the existence of the planet Neptune, nor outside the astronomical profession did the subsequent discovery of a faint remote speck of light in the region of the perturbed planet cause any very great excitement. Scientific people, however, found the intelligence remarkable enough, even before it became known that the new body was rapidly growing larger and brighter, that its motion was quite different from the orderly progress of the planets, and that the deflection of Neptune and its satellite was becoming now of an unprecedented kind.
Few people without a training in science can realise the huge isolation of the solar system. The sun with its specks of planets, its dust of planetoids, and its impalpable comets, swims in a vacant immensity that almost defeats the imagination. Beyond the orbit of Neptune there is space, vacant so far as human observation has penetrated, without warmth or light or sound, blank emptiness, for twenty million times a million miles. That is the smallest estimate of the distance to be traversed before the very nearest of the stars is attained. And, saving a few comets more unsubstantial than the thinnest flame, no matter had ever to human knowledge crossed this gulf of space, until early in the twentieth century this strange wanderer appeared. A vast mass of matter it was, bulky, heavy, rushing without warning out of the black mystery of the sky into the radiance of the sun. By the second day it was clearly visible to any decent instrument, as a speck with a barely sensible diameter, in the constellation Leo near Regulus. In a little while an opera glass could attain it.
On the third day of the new year the newspaper readers of two hemispheres were made aware for the first time of the real importance of this unusual apparition in the heavens. "A Planetary Collision," one London paper headed the news, and proclaimed Duchaine's opinion that this strange new planet would probably collide with Neptune. The leader writers enlarged upon the topic. So that in most of the capitals of the world, on January 3rd, there was an expectation, however vague of some imminent phenomenon in the sky; and as the night followed the sunset round the globe, thousands of men turned their eyes skyward to see—the old familiar stars just as they had always been.
Until it was dawn in London and Pollux setting and the stars overhead grown pale. The Winter's dawn it was, a sickly filtering accumulation of daylight, and the light of gas and candles shone yellow in the windows to show where people were astir. But the yawning policeman saw the thing, the busy crowds in the markets stopped agape, workmen going to their work betimes, milkmen, the drivers of news-carts, dissipation going home jaded and pale, homeless wanderers, sentinels on their beats, and in the country, labourers trudging afield, poachers slinking home, all over the dusky quickening country it could be seen—and out at sea by seamen watching for the day—a great white star, come suddenly into the westward sky!
Brighter it was than any star in our skies; brighter than the evening star at its brightest. It still glowed out white and large, no mere twinkling spot of light, but a small round clear shining disc, an hour after the day had come. And where science has not reached, men stared and feared, telling one another of the wars and pestilences that are foreshadowed by these fiery signs in the Heavens. Sturdy Boers, dusky Hottentots, Gold Coast negroes, Frenchmen, Spaniards, Portuguese, stood in the warmth of the sunrise watching the setting of this strange new star.
And in a hundred observatories there had been suppressed excitement, rising almost to shouting pitch, as the two remote bodies had rushed together, and a hurrying to and fro, to gather photographic apparatus and spectroscope, and this appliance and that, to record this novel astonishing sight, the destruction of a world. For it was a world, a sister planet of our earth, far greater than our earth indeed, that had so suddenly flashed into flaming death. Neptune it was, had been struck, fairly and squarely, by the strange planet from outer space and the heat of the concussion had incontinently turned two solid globes into one vast mass of incandescence. Round the world that day, two hours before the dawn, went the pallid great white star, fading only as it sank westward and the sun mounted above it. Everywhere men marvelled at it, but of all those who saw it none could have marvelled more than those sailors, habitual watchers of the stars, who far away at sea had heard nothing of its advent and saw it now rise like a pigmy moon and climb zenithward and hang overhead and sink westward with the passing of the night.
And when next it rose over Europe everywhere were crowds of watchers on hilly slopes, on house-roofs, in open spaces, staring eastward for the rising of the great new star. It rose with a white glow in front of it, like the glare of a white fire, and those who had seen it come into existence the night before cried out at the sight of it. "It is larger," they cried. "It is brighter!" And, indeed the moon a quarter full and sinking in the west was in its apparent size beyond comparison, but scarcely in all its breadth had it as much brightness now as the little circle of the strange new star.
"It is brighter!" cried the people clustering in the streets. But in the dim observatories the watchers held their breath and peered at one another. "It is nearer," they said. "Nearer!"
And voice after voice repeated, "It is nearer," and the clicking telegraph took that up, and it trembled along telephone wires, and in a thousand cities grimy compositors fingered the type. "It is nearer." Men writing in offices, struck with a strange realisation, flung down their pens, men talking in a thousand places suddenly came upon a grotesque possibility in those words, "It is nearer." It hurried along awakening streets, it was shouted down the frost-stilled ways of quiet villages, men who had read these things from the throbbing tape stood in yellow-lit doorways shouting the news to the passers-by. "It is nearer." Pretty women, flushed and glittering, heard the news told jestingly between the dances, and feigned an intelligent interest they did not feel. "Nearer! Indeed. How curious! How very, very clever people must be to find out things like that!"
Lonely tramps faring through the wintry night murmured those words to comfort themselves—looking skyward. "It has need to be nearer, for the night's as cold as charity. Don't seem much warmth from it if it is nearer, all the same."
"What is a new star to me?" cried the weeping woman kneeling beside her dead.
The schoolboy, rising early for his examination work, puzzled it out for himself—with the great white star, shining broad and bright through the frost-flowers of his window. "Centrifugal, centripetal," he said, with his chin on his fist. "Stop a planet in its flight, rob it of its centrifugal force, what then? Centripetal has it, and down it falls into the sun! And this—!"
"Do we come in the way? I wonder—"
The light of that day went the way of its brethren, and with the later watches of the frosty darkness rose the strange star again. And it was now so bright that the waxing moon seemed but a pale yellow ghost of itself, hanging huge in the sunset. In a South African city a great man had married, and the streets were alight to welcome his return with his bride. "Even the skies have illuminated," said the flatterer. Under Capricorn, two negro lovers, daring the wild beasts and evil spirits, for love of one another, crouched together in a cane brake where the fire-flies hovered. "That is our star," they whispered, and felt strangely comforted by the sweet brilliance of its light.
The master mathematician sat in his private room and pushed the papers from him. His calculations were already finished. In a small white phial there still remained a little of the drug that had kept him awake and active for four long nights. Each day, serene, explicit, patient as ever, he had given his lecture to his students, and then had come back at once to this momentous calculation. His face was grave, a little drawn and hectic from his drugged activity. For some time he seemed lost in thought. Then he went to the window, and the blind went up with a click. Half way up the sky, over the clustering roofs, chimneys and steeples of the city, hung the star.
He looked at it as one might look into the eyes of a brave enemy. "You may kill me," he said after a silence. "But I can hold you—and all the universe for that matter—in the grip of this little brain. I would not change. Even now."
He looked at the little phial. "There will be no need of sleep again," he said. The next day at noon, punctual to the minute, he entered his lecture theatre, put his hat on the end of the table as his habit was, and carefully selected a large piece of chalk. It was a joke among his students that he could not lecture without that piece of chalk to fumble in his fingers, and once he had been stricken to impotence by their hiding his supply. He came and looked under his grey eyebrows at the rising tiers of young fresh faces, and spoke with his accustomed studied commonness of phrasing. "Circumstances have arisen—circumstances beyond my control," he said and paused, "which will debar me from completing the course I had designed. It would seem, gentlemen, if I may put the thing clearly and briefly, that—Man has lived in vain."
The students glanced at one another. Had they heard aright? Mad? Raised eyebrows and grinning lips there were, but one or two faces remained intent upon his calm grey-fringed face. "It will be interesting," he was saying, "to devote this morning to an exposition, so far as I can make it clear to you, of the calculations that have led me to this conclusion. Let us assume—"
He turned towards the blackboard, meditating a diagram in the way that was usual to him. "What was that about 'lived in vain?'" whispered one student to another. "Listen," said the other, nodding towards the lecturer.
And presently they began to understand.
That night the star rose later, for its proper eastward motion had carried it some way across Leo towards Virgo, and its brightness was so great that the sky became a luminous blue as it rose, and every star was hidden in its turn, save only Jupiter near the zenith, Capella, Aldebaran, Sirius and the pointers of the Bear. It was very white and beautiful. In many parts of the world that night a pallid halo encircled it about. It was perceptibly larger; in the clear refractive sky of the tropics it seemed as if it were nearly a quarter the size of the moon. The frost was still on the ground in England, but the world was as brightly lit as if it were midsummer moonlight. One could see to read quite ordinary print by that cold clear light, and in the cities the lamps burnt yellow and wan.
And everywhere the world was awake that night, and throughout Christendom a sombre murmur hung in the keen air over the countryside like the belling of bees in the heather, and this murmurous tumult grew to a clangour in the cities. It was the tolling of the bells in a million belfry towers and steeples, summoning the people to sleep no more, to sin no more, but to gather in their churches and pray. And overhead, growing larger and brighter, as the earth rolled on its way and the night passed, rose the dazzling star.
And the streets and houses were alight in all the cities, the shipyards glared, and whatever roads led to high country were lit and crowded all night long. And in all the seas about the civilised lands, ships with throbbing engines, and ships with bellying sails, crowded with men and living creatures, were standing out to ocean and the north. For already the warning of the master mathematician had been telegraphed all over the world, and translated into a hundred tongues. The new planet and Neptune, locked in a fiery embrace, were whirling headlong, ever faster and faster towards the sun. Already every second this blazing mass flew a hundred miles, and every second its terrific velocity increased. As it flew now, indeed, it must pass a hundred million of miles wide of the earth and scarcely affect it. But near its destined path, as yet only slightly perturbed, spun the mighty planet Jupiter and his moons sweeping splendid round the sun. Every moment now the attraction between the fiery star and the greatest of the planets grew stronger. And the result of that attraction? Inevitably Jupiter would be deflected from its orbit into an elliptical path, and the burning star, swung by his attraction wide of its sunward rush, would "describe a curved path" and perhaps collide with, and certainly pass very close to, our earth. "Earthquakes, volcanic outbreaks, cyclones, sea waves, floods, and a steady rise in temperature to I know not what limit"—so prophesied the master mathematician.
And overhead, to carry out his words, lonely and cold and livid, blazed the star of the coming doom.
To many who stared at it that night until their eyes ached, it seemed that it was visibly approaching. And that night, too, the weather changed, and the frost that had gripped all Central Europe and France and England softened towards a thaw.
But you must not imagine because I have spoken of people praying through the night and people going aboard ships and people fleeing towards mountainous country that the whole world was already in a terror because of the star. As a matter of fact, use and wont still ruled the world, and save for the talk of idle moments and the splendour of the night, nine human beings out of ten were still busy at their common occupations. In all the cities the shops, save one here and there, opened and closed at their proper hours, the doctor and the undertaker plied their trades, the workers gathered in the factories, soldiers drilled, scholars studied, lovers sought one another, thieves lurked and fled, politicians planned their schemes. The presses of the newspapers roared through the nights, and many a priest of this church and that would not open his holy building to further what he considered a foolish panic. The newspapers insisted on the lesson of the year 1000—for then, too, people had anticipated the end. The star was no star—mere gas—a comet; and were it a star it could not possibly strike the earth. There was no precedent for such a thing. Common sense was sturdy everywhere, scornful, jesting, a little inclined to persecute the obdurate fearful. That night, at seven-fifteen by Greenwich time, the star would be at its nearest to Jupiter. Then the world would see the turn things would take. The master mathematician's grim warnings were treated by many as so much mere elaborate self-advertisement. Common sense at last, a little heated by argument, signified its unalterable convictions by going to bed. So, too, barbarism and savagery, already tired of the novelty, went about their nightly business, and save for a howling dog here and there, the beast world left the star unheeded.
And yet, when at last the watchers in the European States saw the star rise, an hour later it is true, but no larger than it had been the night before, there were still plenty awake to laugh at the master mathematician—to take the danger as if it had passed.
But hereafter the laughter ceased. The star grew—it grew with a terrible steadiness hour after hour, a little larger each hour, a little nearer the midnight zenith, and brighter and brighter, until it had turned night into a second day. Had it come straight to the earth instead of in a curved path, had it lost no velocity to Jupiter, it must have leapt the intervening gulf in a day, but as it was it took five days altogether to come by our planet. The next night it had become a third the size of the moon before it set to English eyes, and the thaw was assured. It rose over America near the size of the moon, but blinding white to look at, and hot; and a breath of hot wind blew now with its rising and gathering strength, and in Virginia, and Brazil, and down the St. Lawrence valley, it shone intermittently through a driving reek of thunder-clouds, flickering violet lightning, and hail unprecedented. In Manitoba was a thaw and devastating floods. And upon all the mountains of the earth the snow and ice began to melt that night, and all the rivers coming out of high country flowed thick and turbid, and soon—in their upper reaches—with swirling trees and the bodies of beasts and men. They rose steadily, steadily in the ghostly brilliance, and came trickling over their banks at last, behind the flying population of their valleys.
And along the coast of Argentina and up the South Atlantic the tides were higher than had ever been in the memory of man, and the storms drove the waters in many cases scores of miles inland, drowning whole cities. And so great grew the heat during the night that the rising of the sun was like the coming of a shadow. The earthquakes began and grew until all down America from the Arctic Circle to Cape Horn, hillsides were sliding, fissures were opening, and houses and walls crumbling to destruction. The whole side of Cotopaxi slipped out in one vast convulsion, and a tumult of lava poured out so high and broad and swift and liquid that in one day it reached the sea.
So the star, with the wan moon in its wake, marched across the Pacific, trailed the thunderstorms like the hem of a robe, and the growing tidal wave that toiled behind it, frothing and eager, poured over island and island and swept them clear of men. Until that wave came at last—in a blinding light and with the breath of a furnace, swift and terrible it came—a wall of water, fifty feet high, roaring hungrily, upon the long coasts of Asia, and swept inland across the plains of China. For a space the star, hotter now and larger and brighter than the sun in its strength, showed with pitiless brilliance the wide and populous country; towns and villages with their pagodas and trees, roads, wide cultivated fields, millions of sleepless people staring in helpless terror at the incandescent sky; and then, low and growing, came the murmur of the flood. And thus it was with millions of men that night—a flight nowhither, with limbs heavy with heat and breath fierce and scant, and the flood like a wall swift and white behind. And then death.
China was lit glowing white, but over Japan and Java and all the islands of Eastern Asia the great star was a ball of dull red fire because of the steam and smoke and ashes the volcanoes were spouting forth to salute its coming. Above was the lava, hot gases and ash, and below the seething floods, and the whole earth swayed and rumbled with the earthquake shocks. Soon the immemorial snows of Thibet and the Himalaya were melting and pouring down by ten million deepening converging channels upon the plains of Burmah and Hindostan. The tangled summits of the Indian jungles were aflame in a thousand places, and below the hurrying waters around the stems were dark objects that still struggled feebly and reflected the blood-red tongues of fire. And in a rudderless confusion a multitude of men and women fled down the broad river-ways to that one last hope of men—the open sea.
Larger grew the star, and larger, hotter, and brighter with a terrible swiftness now. The tropical ocean had lost its phosphorescence, and the whirling steam rose in ghostly wreaths from the black waves that plunged incessantly, speckled with storm-tossed ships.
And then came a wonder. It seemed to those who in Europe watched for the rising of the star that the world must have ceased its rotation. In a thousand open spaces of down and upland the people who had fled thither from the floods and the falling houses and sliding slopes of hill watched for that rising in vain. Hour followed hour through a terrible suspense, and the star rose not. Once again men set their eyes upon the old constellations they had counted lost to them forever. In England it was hot and clear overhead, though the ground quivered perpetually, but in the tropics, Sirius and Capella and Aldebaran showed through a veil of steam. And when at last the great star rose near ten hours late, the sun rose close upon it, and in the centre of its white heart was a disc of black.
Over Asia it was the star had begun to fall behind the movement of the sky, and then suddenly, as it hung over India, its light had been veiled. All the plain of India from the mouth of the Indus to the mouths of the Ganges was a shallow waste of shining water that night, out of which rose temples and palaces, mounds and hills, black with people. Every minaret was a clustering mass of people, who fell one by one into the turbid waters, as heat and terror overcame them. The whole land seemed a-wailing, and suddenly there swept a shadow across that furnace of despair, and a breath of cold wind, and a gathering of clouds, out of the cooling air. Men looking up, near blinded, at the star, saw that a black disc was creeping across the light. It was the moon, coming between the star and the earth. And even as men cried to God at this respite, out of the East with a strange inexplicable swiftness sprang the sun. And then star, sun and moon rushed together across the heavens.
So it was that presently, to the European watchers, star and sun rose close upon each other, drove headlong for a space and then slower, and at last came to rest, star and sun merged into one glare of flame at the zenith of the sky. The moon no longer eclipsed the star but was lost to sight in the brilliance of the sky. And though those who were still alive regarded it for the most part with that dull stupidity that hunger, fatigue, heat and despair engender, there were still men who could perceive the meaning of these signs. Star and earth had been at their nearest, had swung about one another, and the star had passed. Already it was receding, swifter and swifter, in the last stage of its headlong journey downward into the sun.
And then the clouds gathered, blotting out the vision of the sky, the thunder and lightning wove a garment round the world; all over the earth was such a downpour of rain as men had never before seen, and where the volcanoes flared red against the cloud canopy there descended torrents of mud. Everywhere the waters were pouring off the land, leaving mud-silted ruins, and the earth littered like a storm-worn beach with all that had floated, and the dead bodies of the men and brutes, its children. For days the water streamed off the land, sweeping away soil and trees and houses in the way, and piling huge dykes and scooping out Titanic gullies over the country side. Those were the days of darkness that followed the star and the heat. All through them, and for many weeks and months, the earthquakes continued.
But the star had passed, and men, hunger-driven and gathering courage only slowly, might creep back to their ruined cities, buried granaries, and sodden fields. Such few ships as had escaped the storms of that time came stunned and shattered and sounding their way cautiously through the new marks and shoals of once familiar ports. And as the storms subsided men perceived that everywhere the days were hotter than of yore, and the sun larger, and the moon, shrunk to a third of its former size, took now fourscore days between its new and new.
But of the new brotherhood that grew presently among men, of the saving of laws and books and machines, of the strange change that had come over Iceland and Greenland and the shores of Baffin's Bay, so that the sailors coming there presently found them green and gracious, and could scarce believe their eyes, this story does not tell. Nor of the movement of mankind now that the earth was hotter, northward and southward towards the poles of the earth. It concerns itself only with the coming and the passing of the Star.
The Martian astronomers—for there are astronomers on Mars, although they are very different beings from men—were naturally profoundly interested by these things. They saw them from their own standpoint of course. "Considering the mass and temperature of the missile that was flung through our solar system into the sun," one wrote, "it is astonishing what a little damage the earth, which it missed so narrowly, has sustained. All the familiar continental markings and the masses of the seas remain intact, and indeed the only difference seems to be a shrinkage of the white discolouration (supposed to be frozen water) round either pole." Which only shows how small the vastest of human catastrophes may seem, at a distance of a few million miles.
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Of the five matter states, the Bose-Einstein condensate has always been the most elusive. Bose-Einstein condensates are clouds of atoms cooled to near absolute zero and, although predicted by Satyendra Nath Bose and Albert Einstein in 1924-25, they were only proven to exist in 1995 in research that was later awarded a Nobel Prize.
Now, researchers at NASA in charge of the Cold Atom Laboratory (CAL) are planning to create these mysterious condensates in space on the International Space Station (ISS). The reason behind this rather strange location for an experiment lies in physics.
Due to Earth’s gravity pull, so far scientists on land have only gotten these tricky condensates to exist for fractions of a second before being disrupted. NASA hopes that the microgravity of the ISS will allow the condensates to last for an impressive 10 seconds.
The Lab is set to provide scientists with 6.5 hours per day of research time and will be operated remotely by physicists on Earth. The facility is also designed for use by several scientific investigators and can be upgraded and maintained while in orbit.
CAL was developed by NASA's Jet Propulsion Laboratory in Pasadena, California on behalf of NASA’s Space Life and Physical Sciences Research and Applications (SLPSRA) Division, in the Human Exploration and Operations Mission Directorate. The Lab consists of an ice chest-sized box equipped with lasers, a vacuum chamber and an electromagnetic "knife."
According to its mission overview, CAL's aim is to "enable research in a temperature regime and force free environment that is inaccessible to terrestrial laboratories." NASA's Physical Science Research Program is currently funding seven proposals to conduct physics research in CAL.
Detecting dark energy
NASA believes that these experiments could lead to improved technologies such as sensors and quantum computers. Most importantly, the research can lead to applications related to the detection of dark energy, currently estimated to comprise 68% of the universe.
"Studying these hyper-cold atoms could reshape our understanding of matter and the fundamental nature of gravity."
"Studying these hyper-cold atoms could reshape our understanding of matter and the fundamental nature of gravity," said CAL Project Scientist Robert Thompson in a statement. "The experiments we'll do with the Cold Atom Lab will give us insight into gravity and dark energy -- some of the most pervasive forces in the universe."
CAL deputy project manager Kamal Oudrhiri explained that even with all of today's advanced technologies its is possible that we are "blind to 95% of the universe" due to our lack of knowledge in dark energy. "Like a new lens in Galileo's first telescope, the ultra-sensitive cold atoms in the Cold Atom Lab have the potential to unlock many mysteries beyond the frontiers of known physics," Oudrhiri added.
CAL launched aboard a Cygnus spacecraft to the ISS on Monday May 21. The Lab will operate on the station for a period of three years that could be extended depending on outcomes.
NASA's researchers have very high hopes for future applications resulting from CAL. “CAL will be a pathfinder for many future space-based cold atom and laser cooling experiments and technology. It could open the door to a new quantum world,” said Anita Sengupta of JPL, Cold Atom Lab project manager. | 0.828699 | 3.461377 |
Daphnis was discovered by the Cassini mission team on 1 May 2005. Prior to its discovery, scientists posited the existence of a moon in Daphnis' position due to the ripples observed along the edge of the Keeler Gap.
Daphnis has a mean radius of 2.4 miles (3.8 km) and orbits 85,000 miles (136,500 km) from Saturn, completing one orbit in 14 hours.
The gravitational pull of tiny inner Saturnian moon Daphnis perturbs the orbits of particles of Saturn's A ring—and sculpting the edge of the Keeler Gap into waves. Material on the inner edge of the gap orbits faster than the moon, so the waves there lead the moon in its orbit. Material on the outer edge moves slower than the moon, so waves there trail the moon. The waves Daphnis causes cast shadows on Saturn during its equinox when the sun is in line with the plane of the rings.
How Daphnis Got its Name
Formerly known as S/2005 S1, Daphnis is named for a shepherd, and pipes player who is a pastoral poet in Greek mythology. Daphnis was the son of Hermes, the brother of Pan and a descendent of the Titans. | 0.847335 | 3.372774 |
Springtime on Earth can be a riotous affair, as plants come back to life and creatures large and small get ready to mate. Nothing like that happens on Mars, of course. But even on a cold world like Mars, springtime brings changes, though you have to look a little more closely to see them.
Lucky for us, there are spacecraft orbiting Mars with high-resolution cameras, and we can track the onset of Martian springtime through images.
We’ve subsisted for months on morsels of information coming from ESA’s mission to Comet 67P/Churyumov-Gerasimenko. Now, a series of scientific papers in journal Science offers a much more complete, if preliminary, look at Rosetta’s comet. And what a wonderful and complex world it is.
Each of the papers describes a different aspect of the comet from the size and density of dust particles jetting from the nucleus, organic materials found on its surface and the diverse geology of its bizarre landscapes. Surprises include finding no firm evidence yet of ice on the comet’s nucleus. There’s no question water and other ices compose much of 67P’s 10 billion ton mass, but much of it’s buried under a thick layer of dust.
It was just about three months ago that the astronomy world watched in awe as the recently-discovered comet Lovejoy plummeted toward the Sun on what was expected to be its final voyage, only to reappear on the other side seemingly unscathed! Surviving its solar visit, Lovejoy headed back out into the solar system, displaying a brand-new tail for skywatchers in southern parts of the world (and for a few select viewers above the world as well.)
How did a loosely-packed ball of ice and rock manage to withstand such a close pass through the Sun’s blazing corona, when all expectations were that it would disintegrate and fizzle away? A few researchers from Germany have an idea.
Scientists from the Max Planck Institute for Extraterrestrial Physics and the Braunschweig University of Technology have hypothesized that Comet Lovejoy managed to hold itself together through the very process that, to most people, defines a comet: the outgassing of sublimated icy material.
As a comet near the Sun, the increased heating from solar radiation causes the frozen materials within the nucleus to sublimate — go directly and suddenly from solid to gas, skipping the liquid middle stage — and, in doing so, burst through the surface of the comet and create the long, hazy reflective tail that is so often associated with them.
In the case of Lovejoy, which was on a direct path toward the Sun, the sublimation itself may have provided enough outward force across its surface to literally keep it together, according to the team’s research.
“The reaction force caused by the strong outgassing (sublimation) of the nucleus near the Sun acts to keep the nucleus together and to overcome the tidal disruption,” the paper claims.
In addition, the team states that the size of the comet’s nucleus can be derived using an equation that takes into consideration the combined forces of outgassing, the material composition of the comet’s nucleus, the comet’s own gravity and the tidal forces exerted by the comet’s close proximity to the Sun (i.e., the Roche limit).
Using that equation, the team concluded that the diameter of Comet Lovejoy’s nucleus is anywhere between 0.2 km and 11 km (.125 miles and 6.8 miles). Any smaller and it would have lost too much material during its pass (and had too little gravity); any larger and it would have been too thick for outgassing to provide enough counterbalancing force.
If this hypothesis is correct, taking a trip around the Sun may not mean the end for all comets… at least not those of a certain size!
Watch the video of Lovejoy’s Dec. 15 solar swing below:
The paper was submitted to the journal Icarus on March 8, 2012 by Bastian Gundlach. See the full text here. | 0.841418 | 3.936107 |
November 2012 Highlights * Leonid meteor shower peaks on the morning of November 17 though rates will be low * Jupiter and the Moon pair up on the evenings of the 1st and 28th * Venus and Saturn pair up on the morning of the 26th-27th * Venus, Mercury and Saturn are all visible in a line at the end of the month Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <[email protected]>.
Mercury – Mercury starts the month very low in the southwest after dusk. It is probably too low for most observers. Luckily it appears in the morning at the end of the month.
Mars – Mars glows at a rather meager +1.2 magnitude this month low in the southwest after dusk. It is only visible for anout an hour after sunset as it continues its slow descent towards the horizon. Use the Moon to find Mars on the evenings of the 15th and 16th.
Jupiter – Jupiter is heading towards its December 2nd opposition. At the start of the month it rises in the northeast around 7:30 to 8:00 pm. On the evening of the first, it makes a spectacular pair with the Moon between the horns of Taurus. The two pair up again on the evening of the 28th. At magnitude -2.6 to -2.7 it is the brightest “star” in the sky with the exception of early morning Venus.
Venus – Venus rises about 2 hours before the Sun this month. In a telescope the planet will appear more than half-illuminated (about 80%). At magnitude – 4.1, Venus is by far the brightest ‘star’ in the morning sky. This November Venus makes a close pairing with the star Theta Virginis on the 12th and 13th, a more distant pairing with 1st magnitude Spica on the 17th and a rather close pairing with Saturn on the 26th and 27th. The Moon also passes to the south of Venus on the morning of the 11th. During the last week of November, Venus, Saturn and Mercury
Saturn – Saturn is an early morning object. Venus passes very close to Saturn on the mornings of the 26th and 27th.
Mercury – The innermost planet pops above the southeast horizon just before dawn during the last week of the month. It is the lower left planet in a line made up of Saturn-Venus-Mercury.
The year is usually split in 2 with January through June having low rates with few major showers while July through December have high rates with many major showers. Meteor activity is still near an annual this month.
Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During November mornings, 10 or so Sporadic meteors can be observed per hour from a dark moonless sky.
Major Meteor Showers
Leonids (LEO) [Max Date = Nov. 17, Max ZHR = ~10-15 per hour]
The Leonids are the result of dust released by Comet Tempel-Tuttle. The comet resides on an orbit that spans from just inside the orbit of the Earth (0.98 AU) to slightly beyond the orbit of Uranus (19.7 AU). It takes the comet ~33 years to orbit the Sun. The the comet last passed perihelion (closest distance to the Sun) in 1998 and was well observed at that time.
The first recorded appearance of the Leonids was in 902 AD when the shower was seen from Italy and Egypt. For the next few centuries, impressive Leonid displays were observed every 33 to 200 years or so.
Two Leonid storms stand out from all the others. On 1833 November 13, the entire eastern United States was awaken to a sight very few had every seen. The sky appeared to be filled with meteors. Modern researchers now know the cause of this outburst. It is estimated that a rate of up to ~70,000 meteors per hour was observed. That works out to ~20 meteor per second.
The 1833 storm marks the dawning of the modern age of meteor science. It was due to observations of this storm that astronomers first recognized that meteors originate in space. About 30 years later, after the discovery of Comets Swift-Tuttle (parent of the Perseids) and Tempel-Tuttle (the parent of the Leonids), the connection between comets and meteor showers was made.
The 1833 storm ranks as one of the 2 best meteor displays in recorded history. 133 years after the 1833 storm, the Leonids once again set the skies ablaze. On the night of 1966 November 17, the western United States experienced a storm just as strong as the 1833 storm.
When the comet returned in 1998, there were many predictions for spectacular Leonid activity. Though meteor rates never got close to that seen in 1833 or 1966, rates as high as a few thousand meteors per hour were observed in multiple years. The best meteor shower I have ever seen was the 1998 Leonid fireball display. Though I would observe Leonid displays with much higher rates of meteors, the sheer number of extremely bright meteors in 1998 was breathtaking.
Unfortunately no major display is forecast for 2012. Rather rates should be a meager 10-15 per hour for observers under dark skies.
The Leonids appear to come from an area in the “sickle” of Leo. This area, called the radiant, rises around midnight local time. It is best to wait till the radiant is high in the sky before looking for meteors (say 2am). The radiant is highest around the start of dawn. Meteors can appear anywhere in the sky so you don’t have to look at the radiant.
Minor Meteor Showers
Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Info on many minor showers are provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.
Additional information on these showers and other minor showers not included here can be found at the International Meteor Organization’s 2012 Meteor Shower Calendar.
Naked Eye Comets (V < 6.0)
None this month.
Binocular Comets (V = 6.0 – 8.0)
None this month
Small Telescope Comets (V = 8.0 – 10.0)
The surprise comet of the year, little 168P was only expected to brighten to magnitude 15 or so this apparition even though it passed within 0.42 AU of the Earth and 1.41 AU of the Sun in late October/early November. A number of outbursts and splitting events resulted in 168P brightening up to 9th magnitude. Recent large telescope observations have detected a secondary nucleus which split off from the main nucleus during on of the outbursts.
As of the 1st of the month, 168P is probably a little fainter than 10th magnitude as it slowly fades after its last outburst. Hopefully another outburst will occur and push the comet back into the realm of small telescope observation. | 0.846971 | 3.170518 |
A sednoid is a trans-Neptunian object with a perihelion greater than 50 AU and a semi-major axis greater than 150 AU. Only three objects are known from this population: 90377 Sedna, 2012 VP113, 2015 TG387, but it is suspected that there are many more. All of them have perihelia greater than 64 AU; these objects lie outside an nearly empty gap in the Solar System starting at about 50 AU, have no significant interaction with the planets. They are grouped with the detached objects; some astronomers, such as Scott Sheppard, consider the sednoids to be inner Oort cloud objects, though the inner Oort cloud, or Hills cloud, was predicted to lie beyond 2,000 AU, beyond the aphelia of the three known sednoids. This definition applies for 2013 SY99 which has a perihelion at 50.02 AU, far beyond the Kuiper cliff, but it is thought not to belong to the Sednoids, but to the same dynamical class as 2004 VN112, 2014 SR349 and 2010 GB174. With these high eccentricities > 0.8 they can be distinguished from the high-perihelion objects with moderate eccentricities which are in a stable resonance with Neptune, 2015 KQ174, 2015 FJ345, 2004 XR190, 2014 FC72 and 2014 FZ71.
The sednoids' orbits cannot be explained by perturbations from the giant planets, nor by interaction with the galactic tides. If they formed in their current locations, their orbits must have been circular, their present elliptical orbits can be explained by several hypotheses: These objects could have had their orbits and perihelion distances "lifted" by the passage of a nearby star when the Sun was still embedded in its birth star cluster. Their orbits could have been disrupted by an as-yet-unknown planet-sized body beyond the Kuiper belt such as the hypothesized Planet Nine, they could have been captured from around passing stars, most in the Sun's birth cluster. The three published sednoids, like all of the more extreme detached objects, have a similar orientation of ≈ 0°; this is not due to an observational bias and is unexpected, because interaction with the giant planets should have randomized their arguments of perihelion, with precession periods between 40 Myr and 650 Myr and 1.5 Gyr for Sedna.
This suggests that more undiscovered massive perturbers may exist in the outer Solar System. A super-Earth at 250 AU would cause these objects to librate around ω = 0°±60° for billions of years. There are multiple possible configurations and a low-albedo super-Earth at that distance would have an apparent magnitude below the current all-sky-survey detection limits; this hypothetical super-Earth has been dubbed Planet Nine. Larger, more-distant perturbers would be too faint to be detected; as of 2016, 27 known objects have a semi-major axis greater than 150 AU, a perihelion beyond Neptune, an argument of perihelion of 340°±55°, an observation arc of more than 1 year. 2013 SY99 is not considered a sednoid. On 1 October 2018, 2015 TG387 was announced with perihelion of 65 AU and a semimajor axis of 1094 AU. With an aphelion of 2123 AU, it brings the object further out than Sedna. In late 2015, V774104 was announced at the Division for Planetary Science conference as a further candidate sednoid, but its observation arc was too short to know whether its perihelion was outside Neptune's influence.
The talk about V774104 was meant to refer to 2015 TG387 though V774104 is the internal designation for non-Sednoid 2015 TH367. Sednoids might constitute a proper dynamical class; each of the proposed mechanisms for Sedna's extreme orbit would leave a distinct mark on the structure and dynamics of any wider population. If a trans-Neptunian planet were responsible, all such objects would share the same perihelion. If Sedna had been captured from another planetary system that rotated in the same direction as the Solar System all of its population would have orbits on low inclinations and have semi-major axes ranging from 100–500 AU. If it rotated in the opposite direction two populations would form, one with low and one with high inclinations; the perturbations from passing stars would produce a wide variety of perihelia and inclinations, each dependent on the number and angle of such encounters. Acquiring a larger sample of such objects would therefore help in determining which scenario is most likely.
"I call Sedna a fossil record of the earliest Solar System", said Brown in 2006. "Eventually, when other fossil records are found, Sedna will help tell us how the Sun formed and the number of stars that were close to the Sun when it formed." A 2007–2008 survey by Brown and Schwamb attempted to locate another member of Sedna's hypothetical population. Although the survey was sensitive to movement out to 1,000 AU and discovered the dwarf planet Gonggong, it detected no new sednoids. Subsequent simulations incorporating the new data suggested about 40 Sedna-sized objects exist in this region, with the brightest being about Eris's magnitude. Following the discovery of 2015 TG387, Sheppard et al. concluded that it implies a population of about 2 million Inner Oort Cloud objects larger than 40 km, with a total mass in the range of 1×1022 kg. New icy body hints at planet lurkin
Temnospondyli is a diverse order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carboniferous and Triassic periods. A few species continued into the Cretaceous. Fossils have been found on every continent. During about 210 million years of evolutionary history, they adapted to a wide range of habitats, including fresh water and coastal marine environments, their life history is well understood, with fossils known from the larval stage and maturity. Most temnospondyls were semiaquatic, although some were fully terrestrial, returning to the water only to breed; these temnospondyls were some of the first vertebrates adapted to life on land. Although temnospondyls are considered amphibians, many had characteristics, such as scales and armour-like bony plates, that distinguish them from modern amphibians. Temnospondyls have been known since the early 19th century, were thought to be reptiles, they were described at various times as batrachians and labyrinthodonts, although these names are now used.
Animals now grouped in Temnospondyli were spread out among several amphibian groups until the early 20th century, when they were found to belong to a distinct taxon based on the structure of their vertebrae. Temnospondyli means "cut vertebrae". Experts disagree over whether temnospondyls were ancestral to modern amphibians, or whether the whole group died out without leaving any descendants. Different hypotheses have placed modern amphibians as the descendants of temnospondyls, another group of early tetrapods called lepospondyls, or as descendants of both groups. Recent studies place a family of temnospondyls called the amphibamids as the closest relatives of modern amphibians. Similarities in teeth and hearing structures link the two groups. Many temnospondyls are much larger than living amphibians, superficially resemble crocodiles. Others resemble salamanders. Most have flat heads that are either blunt or elongated; the skulls are rounded or triangular in shape when viewed from above, are covered in pits and ridges.
The rugged surfaces of bones may have supported blood vessels, which could transfer carbon dioxide to the bones to neutralize acidic build up in the blood. Many temnospondyls have canal-like grooves in their skulls called sensory sulci; the sulci, which run around the nostrils and eye sockets, are part of a lateral line system used to detect vibrations in water. As semiaquatic animals, all known temnospondyls have small limbs with no more than four toes on each front foot and five on each hind foot. Terrestrial temnospondyls have larger, thicker limbs, some have claws. One unusual terrestrial temnospondyl, has long limbs for its body, lived as an active runner able to chase prey. Homologues of most of the bones of temnospondyls are seen in other early tetrapods, aside from a few bones in the skull, such as interfrontals and interparietals, that have developed in some temnospondyl taxa. Most temnospondyls have tabular horns in the backs of their skulls, rounded projections of bone separated from the rest of the skull by indentations called otic notches.
Among the most distinguishing features of temnospondyls are the interpterygoid vacuities, two large holes in the back of the palate. Another pair of holes, are present in front of these vacuities, connect the nasal passage with the mouth. Temnospondyls have teeth on their palates, as well as in their jaws; some of these teeth are so large, they are referred to as tusks. In some temnospondyls, such as Nigerpeton, tusks in the lower jaw pierce the palate and emerge through openings in the top of the skull. Little is known of the soft tissue of temnospondyls. A block of sandstone, described in 2007 from the Early Carboniferous Mauch Chunk Formation of Pennsylvania, included impressions of the bodies of three temnospondyls; these impressions show, when alive, they had smooth skin, robust limbs with webbed feet, a ridge of skin on their undersides. Trackways referable to small temnospondyls have been found in Carboniferous and Permian rocks; the trackways, called batrachichni, are found in strata deposited around freshwater environments, suggesting the animals had some ties to the water.
Unlike modern amphibians, many temnospondyls are covered in small packed scales. The undersides of most temnospondyls are covered in rows of large ventral plates. During early stages of development, they first have only rounded scales. Fossils show, as the animals grew, the scales on the undersides of their bodies developed into large, wide ventral plates; the plates overlap each other in a way. Semiaquatic temnospondyls, such as trematosaurs and capitosaurs, have no evidence of scales, they may have lost scales to make movement easier under water or to allow cutaneous respiration, the absorption of oxygen through the skin. Several groups of temnospondyls have large bony plates on their backs. One temnospondyl, has armour-like plating that covers both its back and underside; the temnospondyl Laidleria has ex
Paul John Kern became President and Chief Operating Officer of AM General LLC on August 1, 2008. Kern is a former United States Army officer. From October 2001 to November 2004, he served as Commanding General of the United States Army Materiel Command. Kern served as the Commander, 4th Infantry Division, he was the senior military assistant to the Secretary of Defense and Deputy Secretary of Defense. Kern served as Team Chief, Light Combat Vehicle Team, Office of the Deputy Chief of Staff for Research and Acquisition, as the Program Branch Chief, Bradley Fighting Vehicle Systems, Michigan, he taught weapon systems and automotive engineering at the United States Military Academy and was the department's research officer. Kern served two tours in Vietnam with the 11th Armored Cavalry Regiment as a platoon leader and troop commander, was a battalion operations officer with the 3rd Armored Division in Germany, he commanded the 5th Battalion, 32nd Armor, 24th Infantry Division at Fort Stewart, Georgia.
Kern is a native of West Orange, New Jersey, attended West Orange High School in his hometown. He was commissioned in 1967 as an Armor officer following graduation from the United States Military Academy. In 1973 he earned master's degrees in both mechanical and civil engineering from the University of Michigan. In June 2004 Kern was chosen to head the internal military investigation of the Abu Ghraib torture scandal referred to as the Fay Report, his awards and decorations include the Defense Distinguished Service Medal, Army Distinguished Service Medal, Silver Star, Defense Superior Service Medal, Legion of Merit, Bronze Star, Bronze Star Medal, Purple Heart, Meritorious Service Medal, Army Commendation Medal, Parachutist Badge, Ranger Tab. Defense Distinguished Service Medal Army Distinguished Service Medal Silver Star Defense Superior Service Medal Legion of Merit with oak leaf cluster Bronze Star with Valor Device and oak leaf cluster, Bronze Star with two oak leaf clusters Purple Heart with two oak leaf clusters Meritorious Service Medal with four oak leaf clusters Army Commendation Medal Parachutist Badge Ranger Tab After retirement in January 2005, Kern joined the Board of Directors of EDO Corporation and iRobot Corporation, is a member of the External Advisory Board of the University of Michigan Department of Mechanical Engineering, a Senior Counselor of The Cohen Group.
Kern now serves as the Chair of Advanced Technology in the Department of Civil and Mechanical Engineering at the United States Military Academy. This article incorporates public domain material from the United States Government document "" | 0.859237 | 3.949418 |
Cosmic inflation: 'Spectacular' discovery hailed
Scientists say they have extraordinary new evidence to support a Big Bang Theory for the origin of the Universe.
Researchers believe they have found the signal left in the sky by the super-rapid expansion of space that must have occurred just fractions of a second after everything came into being.
It takes the form of a distinctive twist in the oldest light detectable with telescopes.
The work will be scrutinised carefully, but already there is talk of a Nobel.
"This is spectacular," commented Prof Marc Kamionkowski, from Johns Hopkins University.
"I've seen the research; the arguments are persuasive, and the scientists involved are among the most careful and conservative people I know," he told BBC News.
The breakthrough was announced by an American team working on a project known as BICEP2.
This has been using a telescope at the South Pole to make detailed observations of a small patch of sky.
The aim has been to try to find a residual marker for "inflation" - the idea that the cosmos experienced an exponential growth spurt in its first trillionth, of a trillionth of a trillionth of a second.
Theory holds that this would have taken the infant Universe from something unimaginably small to something about the size of a marble. Space has continued to expand for the nearly 14 billion years since.
Inflation was first proposed in the early 1980s to explain some aspects of Big Bang Theory that appeared to not quite add up, such as why deep space looks broadly the same on all sides of the sky. The contention was that a very rapid expansion early on could have smoothed out any unevenness.
But inflation came with a very specific prediction - that it would be associated with waves of gravitational energy, and that these ripples in the fabric of space would leave an indelible mark on the oldest light in the sky - the famous Cosmic Microwave Background.
The BICEP2 team says it has now identified that signal. Scientists call it B-mode polarisation. It is a characteristic twist in the directional properties of the CMB. Only the gravitational waves moving through the Universe in its inflationary phase could have produced such a marker. It is a true "smoking gun".
Speaking at the press conference to announce the results, Prof John Kovac of the Harvard-Smithsonian Center for Astrophysics, and a leader of the BICEP2 collaboration, said: "This is opening a window on what we believe to be a new regime of physics - the physics of what happened in the first unbelievably tiny fraction of a second in the Universe."
The signal is reported to be quite a bit stronger than many scientists had dared hope. This simplifies matters, say experts. It means the more exotic models for how inflation worked are no longer tenable.
The results also constrain the energies involved - at 10,000 trillion gigaelectronvolts. This is consistent with ideas for what is termed Grand Unified Theory, the realm where particle physicists believe three of the four fundamental forces in nature can be tied together.
But by associating gravitational waves with an epoch when quantum effects were so dominant, scientists are improving their prospects of one day pulling the fourth force - gravity itself - into a Theory of Everything.
The sensational nature of the discovery means the BICEP2 data will be subjected to intense peer review.
It is possible for the interaction of CMB light with dust in our galaxy to produce a similar effect, but the BICEP2 group says it has carefully checked its data over the past three years to rule out such a possibility.
Other experiments will now race to try to replicate the findings.
Prof Andrew Jaffe from Imperial College London, UK, works on a rival telescope called POLARBEAR. He commented: "A lot of this is technology driven. And the next generation of experiments, like the next generation of POLARBEAR, SPIDER and EBEX, and things like that, will have far more detectors and will go after this signal and hopefully drag out much more detail."
Assuming the BICEP2 results are confirmed, a Nobel Prize seems assured.
Who this would go to is difficult to say, but leading figures on the BICEP2 project and the people who first formulated inflationary theory would be in the running.
One of those pioneers, Prof Alan Guth from the Massachusetts Institute of Technology, told the BBC: "I have been completely astounded. I never believed when we started that anybody would ever measure the non-uniformities of the CMB, let alone the polarisation, which is now what we are seeing.
"I think it is absolutely amazing that it can be measured and also absolutely amazing that it can agree so well with inflation and also the simplest models of inflation - nature did not have to be so kind and the theory didn't have to be right."
British scientist Dr Jo Dunkley, who has been searching through data from the European Planck space telescope for a B-mode signal, commented: "I can't tell you how exciting this is. Inflation sounds like a crazy idea, but everything that is important, everything we see today - the galaxies, the stars, the planets - was imprinted at that moment, in less than a trillionth of a second. If this is confirmed, it's huge."
[email protected] and follow me on Twitter: @BBCAmos | 0.87066 | 3.626376 |
Sculpting the population of planets formed via disc fragmentation
Fragment-fragment interactions can play a key role in sculpting the population of planets formed via direct collapse in gravitationally unstable protostellar discs
It is well known that young protostars are surrounded by a circumstellar disc that may, at very early times, be massive enough to develop a gravitational instability. This instability could lead to gravitational collapse in some parts of the discs, results in the direct formation of gaseous, planetary-mass bodies. This fragmentation, however, is only likely to happen in the outer parts of these discs. It is, therefore, possible that this process may explain some of the wide-orbit planets that have been directly imaged. However, it's also been suggested that some of these objects may spiral inwards, lose mass, and ultimately form part of the closer-in exoplanet population.
In an earlier paper, we generated synthetic populations of objects formed via direct gravitational collapse, and showed that these objects predominantly remain massive and on wide-orbit and that, therefore, are unlikely to contribute to the formation of the close-in exoplanet population. In a recent paper, we've updated this earlier work and considered some processes that were not intially considered. In particular, we included the interaction between fragments in the same disc. This can lead to gaseous objects being scattered onto orbits that are prohibited if fragment-fragment scattering is ignored.
The figure on the right shows the results from this work. The left-hand panel is for the case in which fragment-fragment interactions are ignored, while the right-hand panel shows the outcome if they are included. With fragment-fragment interactions included, we still find that the population is dominated by massive objects on wide orbits. However, there is an increase in the number of objects on closer orbits, and a slight increase in the number of objects that may lose enough mass to become close-in, rocky objects (although their survival is unclear). We also find that many objects are ejected, suggesting that this may be an efficient way to generate free-floating planetary mass bodies. A particular prediction of this work is that we expect most of these systems to only have a few objects that survive on bound orbits, suggesting that direct imaging surveys will probably find few systems in which there are multiple wide orbit companions. | 0.901609 | 3.943838 |
There are several points of evidence that the Oort Cloud exists, though it is indeed still a hypothesis and lacks direct observation.
The first is indirectly observational, as proposed by Ernst Öpik back in 1932 as the source of long-period comets. This was revised by Jan Oort in 1950. All you need to determine an orbit is three observations of the object, separated in time. The greater the separation in time and the more observations, the more certainty we have in its orbit. Comets with periods longer than Pluto's must, by definition, have come from beyond Pluto. Pluto's orbit basically loosely defines the extent of the Kuiper Belt (30-50 AU).
So there needs to be a source for these bound objects, and interstellar ones don't cut it because if they're interstellar, then they should not be on bound orbits.
The second is theoretical: Solar system formation models predict that the formation of the giant planets would have scattered small icy objects into the outer solar system. While some would be given enough energy to completely escape the solar system, others would be scattered out to the hypothetical Oort Cloud.
Third, we've seen Kuiper Belts around other star systems, and it's likely that the Oort Cloud is a continuation of the Kuiper Belt, so this may be evidence for Oort Clouds as well.
So if we need a source for long-period comets and the orbits work out to this cloud beyond the Kuiper Belt, dynamical models predict that the bodies would exist there, and we see similar dynamical structures around other stars, then that's fairly compelling evidence it exists.
But, you are correct that, at present, it is not technologically possible to view comets that are members of the Oort Cloud that are still in the Oort Cloud. Viewing a chunk of ice 1/4 of the way to the nearest star is simply not possible ... yet. | 0.853457 | 3.706182 |
Since it was launched in 1973, NASA’s Pioneer 10 space probe has traveled over thirteen billion miles, and is now hurtling through a region of asteroids and comets known as the Kuiper Belt. Its last radio contact, barely detectable given the probe’s diminishing power levels, was received on 23 January 2003, about thirty-one years after it left the Earth.
During it’s long journey through the universe, should any intelligent beings come across Pioneer 10 (or Pioneer 11, which carries a copy of the same plaque), they’ll be greeted with a pictorial engraving from humanity in the form of a 6 by 9-inch gold anodized plaque bolted to the spacecraft’s frame. The plaque design attempts to convey as much data about humans and the Earth as possible using simple line diagrams, in the hope that whatever beings may find it can learn whence and from where the probe originated.
Among other things, it depicts a naked man and woman, with the right hand of the man raised as a sign of good will. It also indicates the layout of our solar system, as well as our sun’s position relative to a number of pulsars, so that our location can be triangulated from fixed points in space.
When the plaque’s design was revealed to the general public, a number of people were upset about it for various reasons. Because it depicts nudity, there was a huge uproar about NASA “wasting” taxpayer money to send “obscenities” into space. Clearly, the people voicing such pseudo-moral objections were “morons.” Or rather, they had the unfortunate character flaw of being unable to separate an obscene image from a benign, scientifically useful drawing.
There were also many who criticized the complexity of the message, indicating that it would not be immediately understandable to a completely alien civilization. This is certainly true, but the plaque’s designers did not intend for the message to be instantly detectable, only for it to be precise and informative. If found, its discoverers can spend as much time as necessary to decode its message, even if it takes generations.
Still other critics warned that showing a map to the probe’s planet of origin may invite a hostile race to find and attack the Earth. This risk does exist, but even in the extremely unlikely event that the first star a Pioneer probe encounters (two million years from now) is home to a hostile race bent on our destruction, they must first A) detect the fast-moving piece of space debris, B) capture it, C) decode the plaque’s message, D) locate our planet, and E) traverse the distance. This means that at the soonest, such aggressors would be arriving in about three million years.
In point of fact, the chances of the probe ever being discovered by any civilization— hostile or otherwise— are virtually non-existent, even if the universe is teeming with life. Something so tiny is just lost against the enormity of space. So why even bother including message? It seems that it was motivated by pure, unadulterated optimism. On the off chance that the someone, somewhere ever stumbles across our humble probe, it can’t hurt to tell them a little about ourselves.
NASA’s next attempt at making contact with aliens arrived in 1974, when the Arecibo radio telescope was remodeled. To mark the occasion, a high-powered message was beamed towards globular star cluster M13, some 25,100 light years away. This target was selected because it contains such a large number of stars, which might increase the message’s likelihood of being detected by intelligent races—were it not for the fact that M13 will no longer be there when the signal arrives. Be that as it may, the transmission will continue on its course through outer space indefinitely, one day encountering distant galaxies, so something or someone could conceivably receive it.
The graphic representation of the message (pictured) has color added to indicate the different sections. It was originally transmitted in binary, using prime digits to give clues on how to arrange the pixels.
Among other things, it attempts to depict a human, the structure of DNA, and our solar system, but clearly it can’t represent any of those things very clearly in the given space. However, if the message is ever received and decoded, it will certainly be clear to the recipients that it originated from an intelligent source. If nothing else, aliens should be able to deduce the existence of the Atari 2600 game console. If they have a reply, we can expect to receive it in about 50,200 years, assuming we’re still able to listen for it.
But the most ambitious information payloads that we’ve blasted into the cosmos are those attached to the sides of the Voyager 1 and 2 probes, launched in 1977. Each probe has a copy of the same gold gramophone record, which is encoded with sounds and images intended to portray the diversity of life and culture on Earth. The probes also provide a cartridge and a needle for use in reading the records’ contents.
Each record’s data includes images, sounds from nature, recorded greetings in 55 languages, and a selection of music from around the world. Among the encoded photographs, it was originally planned to include a picture of a nude man and a nude pregnant woman, but after the uproar over the nude engravings on the Pioneer plaques, NASA decided against it.
Pictured is the gold-plated protective cover, which is engraved with diagrams describing how to extract the data from the disk, and the same pulsar diagram from the Pioneer probes indicating the record’s place of origin. NASA also had the cover electroplated with Uranium 238, so an advanced race might determine the record’s age by measuring the amount of radioactive decay.
President Carter included a spoken greeting on the record, which included the following:
“We cast this message into the cosmos . . . Of the 200 billion stars in the Milky Way galaxy, some – – perhaps many – – may have inhabited planets and space faring civilizations. If one such civilization intercepts Voyager and can understand these recorded contents, here is our message: We are trying to survive our time so we may live into yours. We hope some day, having solved the problems we face, to join a community of Galactic Civilizations. This record represents our hope and our determination and our goodwill in a vast and awesome universe.”
Of course it is unlikely that any intelligent race will ever stumble across one of our derelict spacecraft, and even if they do, the time scales and distances involved are staggering. Moreover, it’s doubtful that a completely alien intelligence can discern the whole meaning of the diagrams for lack of a common frame of reference. But there would be little doubt that the object is the product of an intelligent race of people, which is perhaps the most important message to convey.
So it seems that the act of including these messages from humanity is really a symbolic statement rather than a serious attempt to communicate with other civilizations. But long after humanity has died off, and the Earth is burned to a crisp by her dying sun, these tiny messengers will continue to tote little pieces of our history throughout the universe. And maybe after drifting for millions of years, one of our messages-in-a-bottle will be discovered, and possibly mark the most exciting event in another civilization’s history. | 0.890657 | 3.012039 |
Crescent ♊ Gemini
Moon phase on 10 May 2070 Saturday is New Moon, less than 1 day young Moon is in Taurus.Share this page: twitter facebook linkedin
Moon rises at sunrise and sets at sunset. It's part facing the Earth is completely in shadow.
Moon is passing about ∠21° of ♉ Taurus tropical zodiac sector.
Lunar disc is not visible from Earth. Moon and Sun apparent angular diameters are ∠1969" and ∠1900".
Next Full Moon is the Flower Moon of May 2070 after 14 days on 25 May 2070 at 01:37.
There is high New Moon ocean tide on this date. Combined Sun and Moon gravitational tidal force working on Earth is strong, because of the Sun-Moon-Earth syzygy alignment.
At 11:08 on this date the Moon completes the old and enters a new synodic month with lunation 870 of Meeus index or 1823 from Brown series.
29 days, 7 hours and 16 minutes is the length of new lunation 870. It is 26 minutes longer than next lunation 871 length.
Length of current synodic month is 5 hours and 28 minutes shorter than the mean length of synodic month, but it is still 41 minutes longer, compared to 21st century shortest.
This New Moon true anomaly is ∠350.2°. At beginning of next synodic month true anomaly will be ∠5.3°. The length of upcoming synodic months will keep increasing since the true anomaly gets closer to the value of New Moon at point of apogee (∠180°).
12 days after point of apogee on 28 April 2070 at 06:11 in ♐ Sagittarius. The lunar orbit is getting closer, while the Moon is moving inward the Earth. It will keep this direction for the next day, until it get to the point of next perigee on 11 May 2070 at 01:00 in ♉ Taurus.
Moon is 363 987 km (226 171 mi) away from Earth on this date. Moon moves closer next day until perigee, when Earth-Moon distance will reach 357 790 km (222 320 mi).
1 day after its descending node on 8 May 2070 at 19:39 in ♈ Aries, the Moon is following the southern part of its orbit for the next 11 days, until it will cross the ecliptic from South to North in ascending node on 21 May 2070 at 18:54 in ♎ Libra.
15 days after beginning of current draconic month in ♎ Libra, the Moon is moving from the second to the final part of it.
11 days after previous South standstill on 29 April 2070 at 10:16 in ♐ Sagittarius, when Moon has reached southern declination of ∠-18.761°. Next 2 days the lunar orbit moves northward to face North declination of ∠18.793° in the next northern standstill on 12 May 2070 at 15:52 in ♊ Gemini.
The Moon is in New Moon geocentric conjunction with the Sun on this date and this alignment forms Sun-Moon-Earth syzygy. | 0.837327 | 3.084901 |
Quasars are fascinating astronomical phenomena. Image Credit: CC BY 4.0 ESO / S. Brunier
Originating deep in the universe, the radio blast is from a quasar - the luminous active nucleus of a distant galaxy.
Scientists believe that this intense burst of energy came from a quasar situated 13 billion light years away - meaning that the emission originated at a time when the universe was much younger.
By analysing the burst, it will be possible to learn more about the history of the cosmos.
"We are seeing P352-15 as it was when the universe was less than a billion years old, or only about 7 percent of its current age," said Chris Carilli of the National Radio Astronomy Observatory (NRAO).
"This is near the end of a period when the first stars and galaxies were re-ionizing the neutral hydrogen atoms that pervaded intergalactic space."
"Further observations may allow us to use this quasar as a background 'lamp' to measure the amount of neutral hydrogen remaining at that time." | 0.827321 | 3.289499 |
Planet Earth has been unknowingly and knowingly beaming radio transmissions into space since the development of radio technology. While science fiction often portrays alien civilizations learning about life on Earth by picking up on our errant transmissions, the speed at which these waves travel means they likely haven’t gotten very far yet; wireless transmission has only been around for around 150 years after all. However, the nearest solar system, Alpha Centauri, is only just four light years away. That means if alien civilizations happen to be found in Alpha Centauri, the transmissions they are currently receiving from Earth are only about four years behind our current time. Hope they like Lady Gaga.
While we’ve so far turned up no concrete evidence of other civilizations in our search for deep space transmissions, more and more evidence is being discovered of so-called “fast radio bursts” (FRB). In particular, a group of FRBs coming from a source known as FRB 121102 has been an increasing subject of astronomical research. This mysterious source still remains unknown and lies close to 3 billion light-years away in the constellation Auriga.
FRB 121102 was first detected in 2012 by the Arecibo Observatory in Puerto Rico and has since been also observed by the Green Bank Telescope in West Virginia. In all, 17 radio bursts have been detected from this mysterious source.
According to a new study of FRB 121102 published in The Astrophysical Journal, the consistent position and strength of of the bursts indicate that the radio waves are not created by a man-made satellite nor could they be ruled out as background radiation:
The underlying origin and timescales of this behavior remains uncertain […] The spectra of those bursts are also not well described by a typical power law and vary significantly from burst to burst.
While many of us would love that to mean that these radio transmissions are being beamed from an alien civilization’s television antennae, the researchers speculate a more natural source is behind these radio anomalies:
The nearly certain extragalactic distance and repeating nature of FRB 121102 lead us to favor an origin for the bursts that invokes a young extragalactic neutron star. Supergiant pulses from young pulsars or magnetars or radio counterparts to magnetar X-ray bursts remain plausible models.
Sigh. Neutron stars. It’s always neutron stars. However, with more and more fast radio bursts being detected all the time, astronomers still believe these anomalous radio signals to be our best bet of finding life elsewhere in the universe. Just this year, the world’s largest radio telescope was constructed in China to aid in the search for possible alien civilizations. Keep those fingers crossed. | 0.865512 | 3.379885 |
Visual astronomy is the practice of pushing our built in optical detectors to the limits of performance. Our eyes are surprisingly good optical instruments, and until the advent of film about a century ago were the only means we had of observing the universe. Even now, in the age of sensitive electronic detectors there are those who appreciate the view of the heavens through our own eyes.
This does not keep some from trying other ways to improve the view. Night vision technology, devices pioneered by the military that amplify the available light, offer intriguing possibilities. Available in compact packages these amplifier image tubes have been incorporated into an eyepiece sized package that can replace a standard eyepiece and offer an amplified image.
The image tube operates by charging a grid to a high voltage inside a small vacuum tube. Incoming light (photons) strike this grid and create a shower of electrons that continue onwards to strike a phosphor screen at the rear of the tube. A single photon can create a shower of hundreds of electrons, a very large signal gain. The phosphor screen glows where struck by photons, creating a image of the amplified signal.
A bright image is seen on the screen of the object, hundreds of times brighter than the original. The image is green, as result of the phosphor, this amplification is a monochromatic process. There is some noise in the image, random “sparkles” called scintillation that result when electrons leave the charged grid in a random fashion.
The images shown here are taken with the Collins I3 eyepiece or I3piece. The device is a very nicely built unit that is about the same size as a modern high quality eyepiece. Actually it is much smaller than some of the large designer eyepieces seen on some telescopes. An internal battery means there are no cables resulting in a neat package. The intensifier has a standard 1.25″ or 2″ nose piece threaded to accept standard astronomy filters.
The image intensifier is not a panacea, there are some objects where the intensifier works well, and others where it does not perform. Globular clusters and planetary nebulae are quite dramatically represented in the intensified view. It is faint, low surface brightness objects like galaxies and extended nebulae that are often better appreciated with a normal eyepiece. Switching back and forth is generally a poor idea as using the intensifier decreases dark adaptation.
During personal observations of galaxy views in two large telescopes side by side, I noted more detail in the un-amplified images compared to those using the intensifier, particularly where subtle detail was concerned. I have had opportunity to observe the same galaxy in my 18″ f/4.5 followed by the view in a 24″ with the intensifier. The images in the intensifier were much brighter, but the contrast range seem compressed, such that HII regions and similar low contrast details disappeared.
One place where the value of the intensifier is undeniable is in public outreach. The live views of bright galaxies show far more detail to the inexperienced observer that they would otherwise have missed in the eyepiece view. A spiral galaxy is clearly a spiral galaxy, even to a first time observer. In addition the intensifier can be used to provide views of faint objects under less that ideal conditions. Addition of a narrowband filter can increase the signal to noise and allow viewing of emission nebulae even with substantial light pollution from natural (e.g. the Moon) or artificial sources.
Unfortunately the Collins intensified eyepieces are no longer available from the manufacturer, though the website still appears functional. There is an equivalent product from BIPH which uses the same technology. At nearly four thousand dollars these devices are not for everyone. they can be used to good effect under the right conditions. | 0.816189 | 3.548145 |
For thirty years or more the expressions “Correlation of the Physical Forces” and “The Conservation of Energy” have been common, yet few persons have taken the necessary pains to think out clearly what mechanical changes take place when one form of energy is transformed into another.
Since Tyndall gave us his book called Heat as a Mode of Motion neither lecturers nor text-books have attempted to explain how all phenomena are the necessary outcome of the various forms of motion. In general, phenomena have been attributed to forces—a metaphysical term, which explains nothing and is merely a stop-gap, and is really not at all needful in these days, seeing that transformable modes of motion, easily perceived and understood, may be substituted in all cases for forces.
In December 1895 the author gave a lecture before the Franklin Institute of Philadelphia, on “Mechanical Conceptions of Electrical Phenomena,” in which he undertook to make clear what happens when electrical phenomena appear. The publication of this lecture in The Journal of the Franklin Institute and in Nature brought an urgent request that it should be enlarged somewhat and published in a form more convenient for the public. The enlargement consists in the addition of a chapter on the “Contrasted Properties of Matter and the Ether,” a chapter containing something which the author believes to be of philosophical importance in these days when electricity is so generally described as a phenomenon of the ether.
Ideas of phenomena ancient and modern, metaphysical and mechanical—Imponderables—Forces, invented and discarded—Explanations—Energy, its factors, Kinetic and Potential—Motions, kinds and transformations of—Mechanical, molecular, and atomic—Invention of Ethers, Faraday's conceptions p. 7
Properties of Matter and Ether compared—Discontinuity versus Continuity—Size of atoms—Astronomical distances—Number of atoms in the universe—Ether unlimited—Kinds of Matter, permanent qualities of—Atomic structure; vortex-rings, their properties—Ether structureless—Matter gravitative, Ether not—Friction in Matter, Ether frictionless—Chemical properties—Energy in Matter and in Ether—Matter as a transformer of Energy—Elasticity—Vibratory rates and waves—Density—Heat—Indestructibility of Matter—Inertia in Matter and in Ether—Matter not inert—Magnetism and Ether waves—States of Matter—Cohesion and chemism affected by temperature—Shearing stress in Solids and in Ether—Ether pressure—Sensation dependent upon Matter—Nervous system not affected by Ether states—Other stresses in Ether—Transformations of Motion—Terminology p. 24
Antecedents of Electricity—Nature of what is transformed—Series of transformations for the production of light—Positive and negative Electricity—Positive and negative twists—Rotations about a wire—Rotation of an arc—Ether a non-conductor—Electro-magnetic waves—Induction and inductive action—Ether stress and atomic position—Nature of an electric current—Electricity a condition, not an entity p. 94
Ideas of phenomena ancient and modern, metaphysical and mechanical—Imponderables—Forces, invented and discarded—Explanations—Energy, its factors, Kinetic and Potential—Motions, kinds and transformations of—Mechanical, molecular, and atomic—Invention of Ethers, Faraday's conceptions.
‘And now we might add something concerning a most subtle spirit which pervades and lies hid in all gross bodies, by the force and action of which spirit the particles of bodies attract each other at near distances, and cohere if contiguous, and electric bodies operate at greater distances, as well repelling as attracting neighbouring corpuscles, and light is emitted, reflected, inflected, and heats bodies, and all sensation is excited, and members of animal bodies move at the command of the will.’—Newton, Principia.
In Newton's day the whole field of nature was practically lying fallow. No fundamental principles were known until the law of gravitation was discovered. This law was behind all the work of Copernicus, Kepler, and Galileo, and what they had done needed interpretation. It was quite natural [Pg 8] that the most obvious and mechanical phenomena should first be reduced, and so the Principia was concerned with mechanical principles applied to astronomical problems. To us, who have grown up familiar with the principles and conceptions underlying them, all varieties of mechanical phenomena seem so obvious, that it is difficult for us to understand how any one could be obtuse to them; but the records of Newton's time, and immediately after this, show that they were not so easy of apprehension. It may be remembered that they were not adopted in France till long after Newton's day. In spite of what is thought to be reasonable, it really requires something more than complete demonstration to convince most of us of the truth of an idea, should the truth happen to be of a kind not familiar, or should it chance to be opposed to our more or less well-defined notions of what it is or ought to be. If those who labour for and attain what they think to be the truth about any matter, were a little better informed concerning mental processes and the conditions under which ideas grow and displace others, they would be more patient with mankind; teachers of every rank might then discover that what is often called stupidity may be nothing else than mental inertia, which can no more be made active by simply willing than can the movement of a cannon ball [Pg 9] by a like effort. We grow into our beliefs and opinions upon all matters, and scientific ideas are no exceptions.
Whewell, in his History of the Inductive Sciences, says that the Greeks made no headway in physical science because they lacked appropriate ideas. The evidence is overwhelming that they were as observing, as acute, as reasonable as any who live to-day. With this view, it would appear that the great discoverers must have been men who started out with appropriate ideas: were looking for what they found. If, then, one reflects upon the exceeding great difficulty there is in discovering one new truth, and the immense amount of work needed to disentangle it, it would appear as if even the most successful have but indistinct ideas of what is really appropriate, and that their mechanical conceptions become clarified by doing their work. This is not always the fact. In the statement of Newton quoted at the head of this chapter, he speaks of a spirit which lies hid in all gross bodies, etc., by means of which all kinds of phenomena are to be explained; but he deliberately abandons that idea when he comes to the study of light, for he assumes the existence and activity of light corpuscles, for which he has no experimental evidence; and the probability is that he did this because the latter conception was one which he [Pg 10] could handle mathematically, while he saw no way for thus dealing with the other. His mechanical instincts were more to be trusted than his carefully calculated results; for, as all know, what he called “spirits,” is what to-day we call the ether, and the corpuscular theory of light has now no more than a historic interest. The corpuscular theory was a mechanical conception, but each such corpuscle was ideally endowed with qualities which were out of all relation with the ordinary matter with which it was classed.
Until the middle of the present century the reigning physical philosophy held to the existence of what were called imponderables. The phenomena of heat were explained as due to an imponderable substance called “caloric,” which ordinary matter could absorb and emit. A hot body was one which had absorbed an imponderable substance. It was, therefore, no heavier than before, but it possessed ability to do work proportional to the amount absorbed. Carnot's ideal engine was described by him in terms that imply the materiality of heat. Light was another imponderable substance, the existence of which was maintained by Sir David Brewster as long as he lived. Electricity and magnetism were imponderable fluids, which, when allied with ordinary matter, endowed the latter with their peculiar qualities. The conceptions [Pg 11] in each case were properly mechanical ones part (but not all) of the time; for when the immaterial substances were dissociated from matter, where they had manifested themselves, no one concerned himself to inquire as to their whereabouts. They were simply off duty, but could be summoned, like the genii in the story of Aladdin's Lamp. Now, a mechanical conception of any phenomenon, or a mechanical explanation of any kind of action, must be mechanical all the time, in the antecedents as well as the consequents. Nothing else will do except a miracle.
During the fifty years, from about 1820 to 1870, a somewhat different kind of explanation of physical events grew up. The interest that was aroused by the discoveries in all the fields of physical science—in heat, electricity, magnetism and chemistry—by Faraday, Joule, Helmholtz, and others, compelled a change of conceptions; for it was noticed that each special kind of phenomenon was preceded by some other definite and known kind; as, for instance, that chemical action preceded electrical currents, that mechanical or electrical activity resulted from changing magnetism, and so on. As each kind of action was believed to be due to a special force, there were invented such terms as mechanical force, electrical force, magnetic, chemical and vital forces, and these were discovered to be [Pg 12] convertible into one another, and the “doctrine of the correlation of the physical forces” became a common expression in philosophies of all sorts. By “convertible into one another,” was meant, that whenever any given force appeared, it was at the expense of some other force; thus, in a battery chemical force was changed into electrical force; in a magnet, electrical force was changed into magnetic force, and so on. The idea here was the transformation of forces, and forces were not so clearly defined that one could have a mechanical idea of just what had happened. That part of the philosophy was no clearer than that of the imponderables, which had largely dropped out of mind. The terminology represented an advance in knowledge, but was lacking in lucidity, for no one knew what a force of any kind was.
The first to discover this and to repudiate the prevailing terminology were the physiologists, who early announced their disbelief in a vital force, and their belief that all physiological activities were of purely physical and chemical origin, and that there was no need to assume any such thing as a vital force. Then came the discovery that chemical force, or affinity, had only an adventitious existence, and that, at absolute zero, there was no such activity. The discovery of, or rather the appreciation of, what is implied by the term absolute zero, and [Pg 13] especially of the nature of heat itself, as expressed in the statement that heat is a mode of motion, dismissed another of the so-called forces as being a metaphysical agency having no real existence, though standing for phenomena needing further attention and explanation; and by explanation is meant the presentation of the mechanical antecedents for a phenomenon, in so complete a way that no supplementary or unknown factors are necessary. The train moves because the engine pulls it; the engine pulls because the steam pushes it. There is no more necessity for assuming a steam force between the steam and the engine, than for assuming an engine force between the engine and the train. All the processes are mechanical, and have to do only with ordinary matter and its conditions, from the coal-pile to the moving freight, though there are many transformations of the forms of motion and of energy between the two extremes.
During the past thirty years there has come into common use another term, unknown in any technical sense before that time, namely, energy. What was once called the conservation of force is now called the conservation of energy, and we now often hear of forms of energy. Thus, heat is said to be a form of energy, and the forms of energy are convertible into one another, as the so-called forces were formerly supposed to be transformable into one another. [Pg 14] We are asked to consider gravitative energy, heat energy, mechanical energy, chemical energy, and electrical energy. When we inquire what is meant by energy, we are informed that it means ability to do work, and that work is measurable as a pressure into a distance, and is specified as foot-pounds. A mass of matter moves because energy has been spent upon it, and has acquired energy equal to the work done on it, and this is believed to hold true, no matter what the kind of energy was that moved it. If a body moves, it moves because another body has exerted pressure upon it, and its energy is called kinetic energy; but a body may be subject to pressure and not move appreciably, and then the body is said to possess potential energy. Thus, a bent spring and a raised weight are said to possess potential energy. In either case, an energized body receives its energy by pressure, and has ability to produce pressure on another body. Whether or not it does work on another body depends on the rigidity of the body it acts upon. In any case, it is simply a mechanical action—body A pushes upon body B (Fig. 1). There is no need to assume anything more mysterious than mechanical action. Whether body B moves this way or that depends upon the direction of the push, the point of its application. Whether the body be a mass as large as the earth or as small as a molecule, makes no difference in [Pg 15] that particular. Suppose, then, that a (Fig. 2) spends its energy on b, b on c, c on d, and so on. The energy of a gives translatory motion to b, b sets c vibrating, and c makes d spin on some axis. Each of these has had energy spent on it, and each has some form of energy different from the other, but no new factor has been introduced between a and d, and the only factor that has gone from a to d has been motion—motion that has had its direction and quality changed, but not its nature. If we agree that energy is neither created nor annihilated, by any physical process, and if we assume that a gave to b all its energy, that is, all its motion; that b likewise gave its all to c, and so on; then the succession of phenomena [Pg 16] from a to d has been simply the transference of a definite amount of motion, and therefore of energy, from the one to the other; for motion has been the only variable factor. If, furthermore, we should agree to call the translatory motion α, the vibratory motion β, the rotary γ, then we should have had a conversion of α into β, of β into γ. If we should consider the amount of transfer motion instead of the kind of motion, we should have to say that the α energy had been transformed into β and the β into γ.
What a given amount of energy will do depends only upon its form, that is, the kind of motion that embodies it.
The energy spent upon a stone thrown into the air, giving it translatory motion, would, if spent upon a tuning fork, make it sound, but not move it from its place; while if spent upon a top, would enable the latter to stand upon its point as easily as a person stands on his two feet, and to do other surprising things, which otherwise it could not do. One can, without difficulty, form a mechanical conception of the whole series without assuming imponderables, or fluids or forces. Mechanical motion only, by pressure, has been transferred in certain directions at certain rates. Suppose now that some one should suddenly come upon a spinning top (Fig. 3) while it was standing upon its point, [Pg 17] and, as its motion might not be visible, should cautiously touch it. It would bound away with surprising promptness, and, if he were not instructed in the mechanical principles involved, he might fairly well draw the conclusion that it was actuated by other than simple mechanical principles, and, for that reason, it would be difficult to persuade him that there was nothing essentially different in the body that appeared and acted thus, than in a stone thrown into the air; nevertheless, that statement would be the simple truth.
All our experience, without a single exception, enforces the proposition that no body moves in any direction, or in any way, except when some other body in contact with it presses upon it. The action is direct. In Newton's letter to his friend [Pg 18] Bentley, he says—“That one body should act upon another through empty space, without the mediation of anything else by and through which their action and pressure may be conveyed from one to another, is to me so great an absurdity that I believe no man who has in philosophical matters a competent faculty of thinking can ever fall into it.”
For mathematical purposes, it has sometimes been convenient to treat a problem as if one body could act upon another without any physical medium between them; but such a conception has no degree of rationality, and I know of no one who believes in it as a fact. If this be granted, then our philosophy agrees with our experience, and every body moves because it is pushed, and the mechanical antecedent of every kind of phenomenon is to be looked for in some adjacent body possessing energy—that is, the ability to push or produce pressure.
It must not be forgotten that energy is not a simple factor, but is always a product of two factors—a mass with a velocity, a mass with a temperature, a quantity of electricity into a pressure, and so on. One may sometimes meet the statement that matter and energy are the two realities; both are spoken of as entities. It is much more philosophical to speak of matter and motion, for in the absence of motion there is no energy, and the [Pg 19] energy varies with the amount of motion; and furthermore, to understand any manifestation of energy one must inquire what kind of motion is involved. This we do when we speak of mechanical energy as the energy involved in a body having a translatory motion; also, when we speak of heat as a vibratory, and of light as a wave motion. To speak of energy without stating or implying these distinctions, is to speak loosely and to keep far within the bounds of actual knowledge. To speak thus of a body possessing energy, or expending energy, is to imply that the body possesses some kind of motion, and produces pressure upon another body because it has motion. Tait and others have pointed out the fact, that what is called potential energy must, in its nature, be kinetic. Tait says—“Now it is impossible to conceive of a truly dormant form of energy, whose magnitude should depend, in any way, upon the unit of time; and we are forced to conclude that potential energy, like kinetic energy, depends (even if unexplained or unimagined) upon motion.” All this means that it is now too late to stop with energy as a final factor in any phenomenon, that the form of motion which embodies the energy is the factor that determines what happens, as distinguished from how much happens. Here, then, are to be found the distinctions which have heretofore been [Pg 20] called forces; here is embodied the proof that direct pressure of one body upon another is what causes the latter to move, and that the direction of movement depends on the point of application, with reference to the centre of mass.
It is needful now to look at the other term in the product we call energy, namely, the substance moving, sometimes called matter or mass. It has been mentioned that the idea of a medium filling space was present to Newton, but his gravitation problem did not require that he should consider other factors than masses and distances. The law of gravitation as considered by him was—Every particle of matter attracts every other particle of matter with a stress which is proportional to the product of their masses, and inversely to the squares of the distance between them. Here we are concerned only with the statement that every particle of matter attracts every other particle of matter. Everything then that possesses gravitative attraction is matter in the sense in which that term is used in this law. If there be any other substance in the universe that is not thus subject to gravitation, then it is improper to call it matter, otherwise the law should read, “Some particles of matter attract,” etc., which will never do.
We are now assured that there is something else in the universe which has no gravitative property [Pg 21] at all, namely, the ether. It was first imagined in order to account for the phenomena of light, which was observed to take about eight minutes to come from the sun to the earth. Then Young applied the wave theory to the explanation of polarization and other phenomena; and in 1851 Foucault proved experimentally that the velocity of light was less in water than in air, as it should be if the wave theory be true, and this has been considered a crucial experiment which took away the last hope for the corpuscular theory, and demonstrated the existence of the ether as a space-filling medium capable of transmitting light-waves known to have a velocity of 186,000 miles per second. It was called the luminiferous ether, to distinguish it from other ethers which had also been imagined, such as electric ether for electrical phenomena, magnetic ether for magnetic phenomena, and so on—as many ethers, in fact, as there were different kinds of phenomena to be explained.
It was Faraday who put a stop to the invention of ethers, by suggesting that the so-called luminiferous ether might be the one concerned in all the different phenomena, and who pointed out that the arrangement of iron filings about a magnet was indicative of the direction of the stresses in the ether. This suggestion did not meet the approval of the mathematical physicists of his day, for it necessitated [Pg 22] the abandonment of the conceptions they had worked with, as well as the terminology which had been employed, and made it needful to reconstruct all their work to make it intelligible—a labour which was the more distasteful as it was forced upon them by one who, although expert enough in experimentation, was not a mathematician, and who boasted that the most complicated mathematical work he ever did was to turn the crank of a calculating machine; who did all his work, formed his conclusions, and then said—“The work is done; hand it over to the computers.”
It has turned out that Faraday's mechanical conceptions were right. Every one now knows of Maxwell's work, which was to start with Faraday's conceptions as to magnetic phenomena, and follow them out to their logical conclusions, applying them to molecules and the reactions of the latter upon the ether. Thus he was led to conclude that light was an electro-magnetic phenomenon; that is, that the waves which constitute light, and the waves produced by changing magnetism were identical in their nature, were in the same medium, travelled with the same velocity, were capable of refraction, and so on. Now that all this is a matter of common knowledge to-day, it is curious to look back no further than ten years. Maxwell's conclusions [Pg 23] were adopted by scarcely a physicist in the world. Although it was known that inductive action travelled with finite velocity in space, and that an electro-magnet would affect the space about it practically inversely as the square of the distance, and that such phenomena as are involved in telephonic induction between circuits could have no other meaning than the one assigned by Maxwell, yet nearly all the physicists failed to form the only conception of it that was possible, and waited for Hertz to devise apparatus for producing interference before they grasped it. It was even then so new, to some, that it was proclaimed to be a demonstration of the existence of the ether itself, as well as a method of producing waves short enough to enable one to notice interference phenomena. It is obvious that Hertz himself must have had the mechanics of wave-motion plainly in mind, or he would not have planned such experiments. The outcome of it all is, that we now have experimental demonstration, as well as theoretical reason for believing, that the ether, once considered as only luminiferous, is concerned in all electric and magnetic phenomena, and that waves set up in it by electro-magnetic actions are capable of being reflected, refracted, polarized, and twisted, in the same way as ordinary light-waves can be, and that the laws of optics are applicable to both.
Properties of Matter and Ether compared—Discontinuity versus Continuity—Size of atoms—Astronomical distances—Number of atoms in the universe—Ether unlimited—Kinds of Matter, permanent qualities of—Atomic structure; vortex-rings, their properties—Ether structureless—Matter gravitative, Ether not—Friction in Matter, Ether frictionless—Chemical properties—Energy in Matter and in Ether—Matter as a transformer of Energy—Elasticity—Vibratory rates and waves—Density—Heat—Indestructibility of Matter—Inertia in Matter and in Ether—Matter not inert—Magnetism and Ether waves—States of Matter—Cohesion and chemism affected by temperature—Shearing stress in Solids and in Ether—Ether pressure—Sensation dependent upon Matter—Nervous system not affected by Ether states—Other stresses in Ether—Transformations of Motion—Terminology.
A common conception of the ether has been that it is a finer-grained substance than ordinary matter, but otherwise so like the latter that the laws found to hold good with matter were equally applicable to the ether, and hence the mechanical conceptions [Pg 25] formed from experience in regard to the one have been transferred to the other, and the properties belonging to one, such as density, elasticity, etc., have been asserted as properties of the other.
There is so considerable a body of knowledge bearing upon the similarities and dissimilarities of these two entities that it will be well to compare them. After such comparison one will be better able to judge of the propriety of assuming them to be subject to identical laws.
Matter is made up of atoms having dimensions approximately determined to be in the neighbourhood of the one fifty-millionth of an inch in diameter. These atoms may have various degrees of aggregation;—they may be in practical contact, as in most solid bodies such as metals and rocks; in molecular groupings as in water, and in gases such as hydrogen, oxygen, and so forth, where two, three, or more atoms cohere so strongly as to enable the molecules to act under ordinary circumstances like simple particles. Any or all of these molecules and atoms may be separated by any assignable distance from each other. Thus, in common air the molecules, though rapidly changing their positions, are on the average about two hundred and fifty times their own diameter apart. [Pg 26] This is a distance relatively greater than the distance apart of the earth and the moon, for two hundred and fifty times the diameter of the earth will be 8000 × 250 = 2,000,000 miles, while the distance to the moon is but 240,000 miles. The sun is 93,000,000 miles from the earth, and the most of the bodies of the solar system are still more widely separated, Neptune being nearly 3000 millions of miles from the sun. As for the fixed stars, they are so far separated from us that, at the present rate of motion of the solar system in its drift through space—500 millions of miles in a year—it would take not less than 40,000 years to reach the nearest star among its neighbours, while for the more remote ones millions of years must be reckoned. The huge space separating these masses is practically devoid of matter; it is a vacuum.
The idea of continuity as distinguished from discontinuity may be gained by considering what would be made visible by magnification. Water appears to the eye as if it were without pores, but if sugar or salt be put into it, either will be dissolved and quite disappear among the molecules of the water as steam does in the air, which shows that there are some unoccupied spaces between the molecules. [Pg 27] If a microscope be employed to magnify a minute drop of water it still shows the same lack of structure as that looked at with the unaided eye. If the magnifying power be the highest it may reveal a speck as small as the hundred-thousandth part of an inch, yet the speck looks no different in character. We know that water is composed of two different kinds of atoms, hydrogen and oxygen, for they can be separated by chemical means and kept in separate bottles, and again made to combine to form water having all the qualities that belonged to it before it was decomposed. If a very much higher magnifying power were available, we should ultimately be able to see the individual water molecules, and recognize their hydrogen and oxygen constituents by their difference in size, rate of movements, and we might possibly separate them by mechanical methods. What one would see would be something very different in structure from the water as it appears to our eyes. If the ether were similarly to be examined through higher and still higher magnifying powers, even up to infinity, there is no reason for thinking that the last examination would show anything different in structure or quality from that which was examined with low power or with no microscope at all. This is all expressed by saying that the ether is a continuous substance, without interstices, that it fills space completely, [Pg 28] and, unlike gases, liquids, and solids, is incapable of absorbing or dissolving anything.
There appears to be a definite amount of matter in the visible universe, a definite number of molecules and atoms. How many molecules there are in a cubic inch of air under ordinary pressure has been determined, and is represented approximately by a huge number, something like a thousand million million millions.
When the diameter of a molecule has been measured, as it has been approximately, and found to be about one fifty-millionth of an inch, then fifty million in a row would reach an inch, and the cube of fifty million is 125,000,000000,000000,000000, one hundred and twenty-five thousand million million millions. In a cubic foot there will of course be 1728 times that number. One may if one likes find how many there may be in the earth, and moon, sun and planets, for the dimensions of them are all very well known. Only the multiplication table need be used, and the sum of all these will give how many molecules there are in the solar system. If one should feel that the number thus obtained was not very accurate, he might reflect that if there were ten times as many it would add but another cipher to a long line of similar ones and would not [Pg 29] materially modify it. The point is that there is a definite, computable number. If one will then add to these the number of molecules in the more distant stars and nebulæ, of which there are visible about 100,000,000, making such estimate of their individual size as he thinks prudent, the sum of all will give the number of molecules in the visible universe. The number is not so large but it can be written down in a minute or two. Those who have been to the pains to do the sum say it may be represented by seven followed by ninety-one ciphers. One could easily compute how many molecules so large a space would contain if it were full and as closely packed as they are in a drop of water, but there would be a finite and not an infinite number, and therefore there is a limited number of atoms in the visible universe.
The evidence for this comes to us from the phenomena of light. Experimentally, ether waves of all lengths are found to have a velocity of 186,000 miles in a second. It takes about eight minutes to reach us from the sun, four hours from Neptune the most distant planet, and from the nearest fixed star about three and a half years. Astronomers tell us that some visible stars are so distant that their light requires not less than ten [Pg 30] thousand years and probably more to reach us, though travelling at the enormous rate of 186,000 miles a second. This means that the whole of space is filled with this medium. If there were any vacant spaces, the light would fail to get through them, and stars beyond them would become invisible. There are no such vacant spaces, for any part of the heavens shows stars beaming continuously, and every increase in telescopic power shows stars still further removed than any seen before. The whole of this intervening space must therefore be filled with the ether. Some of the waves that reach us are not more than the hundred-thousandth of an inch long, so there can be no crack or break or absence of ether from so small a section as the hundred-thousandth of an inch in all this great expanse. More than this. No one can think that the remotest visible stars are upon the boundary of space, that if one could get to the most distant star he would have on one side the whole of space while the opposite side would be devoid of it. Space we know is of three dimensions, and a straight line may be prolonged in any direction to an infinite distance, and a ray of light may travel on for an infinite time and come to no end provided space be filled with ether.
How long the sun and stars have been shining no one knows, but it is highly probable that the sun has [Pg 31] existed for not less than 1000 million years, and has during that time been pouring its rays as radiant energy into space. If then in half that time, or 500 millions of years, the light had somewhere reached a boundary to the ether, it could not have gone beyond but would have been reflected back into the ether-filled space, and such part of the sky would be lit up by this reflected light. There is no indication that anything like reflection comes to us from the sky. This is equivalent to saying that the ether fills space in every direction away from us to an unlimited distance, and so far is itself unlimited.
The various kinds of matter we are acquainted with are commonly called the elements. These when combined in various ways exhibit characteristic phenomena which depend upon the kinds of matter, the structure and motions which are involved. There are some seventy different kinds of this elemental matter which may be identified as constituents of the earth. Many of the same elements have been identified in the sun and stars, such for instance as hydrogen, carbon, and iron. Such phenomena lead us to conclude that the kinds of matter elsewhere in the universe are identical with such as we are familiar with, and that elsewhere the variety is as great. The qualities of the elements, [Pg 32] within a certain range of temperature, are permanent; they are not subject to fluctuations, though the qualities of combinations of them may vary indefinitely. The elements therefore may be regarded as retaining their identity in all ordinary experience.
One part of the ether is precisely like any other part everywhere and always, and there are no such distinctions in it as correspond with the elemental forms of matter.
There is an ultimate particle of each one of the elements which is practically absolute and known as an atom. The atom retains its identity through all combinations and processes. It may be here or there, move fast or slow, but its atomic form persists.
One might infer, from what has already been said about continuity, that the ether could not be constituted of separable particles like masses of matter; for no matter how minute they might be, there would be interspaces and unoccupied spaces which would present us with phenomena which have never [Pg 33] been seen. It is the general consensus of opinion among those who have studied the subject that the ether is not atomic in structure.
Every atom of every element is so like every other atom of the same element as to exhibit the same characteristics, size, weight, chemical activity, vibratory rate, etc., and it is thus shown conclusively that the structural form of the elemental particles is the same for each element, for such characteristic reactions as they exhibit could hardly be if they were mechanically unlike.
Of what form the atoms of an element may be is not very definitely known. The earlier philosophers assumed them to be hard round particles, but later thinkers have concluded that atoms of such a character are highly improbable, for they could not exhibit in this case the properties which the elements do exhibit. They have therefore dismissed such a conception from consideration. In place of this hypothesis has been substituted a very different idea, namely, that an atom is a vortex-ring of ether floating in the ether, as a smoke-ring [Pg 34] puffed out by a locomotive in still air may float in the air and show various phenomena.
A vortex-ring produced in the air behaves in the most surprising manner.
1. It retains its ring form and the same material rotating as it starts with.
2. It can travel through the air easily twenty or thirty feet in a second without disruption.
3. Its line of motion when free is always at right angles to the plane of the ring.
4. It will not stand still unless compelled by some object. If stopped in the air it will start up itself to travel on without external help.
5. It possesses momentum and energy like a solid body.
6. It is capable of vibrating like an elastic body, making a definite number of such vibrations per second, the degree of elasticity depending upon the rate of vibration. The swifter the rotation, the more rigid and elastic it is.
7. It is capable of spinning on its own axis, and thus having rotary energy as well as translatory and vibratory.
8. It repels light bodies in front of it, and attracts into itself light bodies in its rear.
9. If projected along parallel with the top of a long table, it will fall upon it every time, just as a stone thrown horizontally will fall to the ground.
10. If two rings of the same size be travelling in the same line, and the rear one overtakes the other, the front one will enlarge its diameter, while the rear one will contract its own till it can go through the forward one, when each will recover its original diameter, and continue on in the same direction, but vibrating, expanding and contracting their diameters with regularity.
11. If two rings be moving in the same line, but in opposite directions, they will repel each other when near, and thus retard their speed. If one goes through the other, as in the former case, it may quite lose its velocity, and come to a standstill in the air till the other has moved [Pg 36] on to a distance, when it will start up in its former direction.
12. If two rings be formed side by side, they will instantly collide at their edges, showing strong attraction.
13. If the collision does not destroy them, they may either break apart at the point of the collision, and then weld together into a single ring with twice the diameter, and then move on as if a single ring had been formed, or they may simply bounce away from each other, in which case they always rebound in a plane at right angles to the plane of collision. That is, if they collided on their sides, they would rebound so that one went up and the other down.
14. Three may in like manner collide and fuse into a single ring.
Such rings formed in air by a locomotive may rise wriggling in the air to the height of several hundred feet, but they are soon dissolved and disappear. This is because the friction and viscosity of the air robs the rings of their substance and energy. If the air were without friction this could not happen, and the rings would then be persistent, and would retain all their qualities.
Suppose then that such rings were produced in a medium without friction as the ether is believed to be, they would be permanent structures with a variety of properties. They would occupy space, have definite form and dimensions, momentum, energy, attraction and repulsion, elasticity; obey the laws of motion, and so far behave quite like such matter as we know. For such reasons [Pg 37] it is thought by some persons to be not improbable that the atoms of matter are minute vortex-rings of ether in the ether. That which distinguishes the atom from the ether is the form of motion which is embodied in it, and if the motion were simply arrested, there would be nothing to distinguish the atom from the ether into which it dissolved. In other words, such a conception makes the atoms of matter a form of motion of the ether, and not a created something put into the ether.
If the ether be the boundless substance described, it is clear it can have no form as a whole, and if it be continuous it can have no minute structure. If not constituted of atoms or molecules there is nothing descriptive that can be said about it. A molecule or a particular mass of matter could be identified by its form, and is thus in marked contrast with any portion of ether, for the latter could not be identified in a similar way. One may therefore say that the ether is formless.
The law of gravitation is held as being universal. According to it every particle of matter in the universe attracts every other particle. The evidence [Pg 38] for this law in the solar system is complete. Sun, planets, satellites, comets and meteors are all controlled by gravitation, and the movements of double stars testify to its activity among the more distant bodies of the universe. The attraction does not depend upon the kind of matter nor the arrangement of molecules or atoms, but upon the amount or mass of matter present, and if it be of a definite kind of matter, as of hydrogen or iron, the gravitative action is proportional to the number of atoms.
One might infer already that if the ether were structureless, physical laws operative upon such material substances as atoms could not be applicable to it, and so indeed all the evidence we have shows that gravitation is not one of its properties. If it were, and it behaved in any degree like atomic structures, it would be found to be denser in the neighbourhood of large bodies like the earth, planets, and the sun. Light would be turned from its straight path while travelling in such denser medium, or made to move with less velocity. There is not the slightest indication of any such effect anywhere within the range of astronomical vision.
Gravitation then is a property belonging to [Pg 39] matter and not to ether. The impropriety of thinking or speaking of the ether as matter of any kind will be apparent if one reflects upon the significance of the law of gravitation as stated. Every particle of matter in the universe attracts every other particle. If there be anything else in the universe which has no such quality, then it should not be called matter, else the law should read: Some particles of matter attract some other particles, which would be no law at all, for a real physical law has no exceptions any more than the multiplication table has. Physical laws are physical relations, and all such relations are quantitative.
A bullet shot into the air has its velocity continuously reduced by the air, to which its energy is imparted by making it move out of its way. A railway train is brought to rest by the friction brake upon the wheels. The translatory energy of the train is transformed into the molecular energy called heat. The steamship requires to propel it fast, a large amount of coal for its engines, because the water in which it moves offers great friction—resistance which must be overcome. Whenever one surface of matter is moved in contact with another surface there is a resistance called friction, [Pg 40] the moving body loses its rate of motion, and will presently be brought to rest unless energy be continuously supplied. This is true for masses of matter of all sizes and with all kinds of motion. Friction is the condition for the transformation of all kinds of mechanical motions into heat. The test of the amount of friction is the rate of loss of motion. A top will spin some time in the air because its point is small. It will spin longer on a plate than on the carpet, and longer in a vacuum than in the air, for it does not have the air friction to resist it, and there is no kind or form of matter not subject to frictional resistance.
The earth is a mass of matter moving in the ether. In the equatorial region the velocity of a point is more than a thousand miles in an hour, for the circumference of the earth is 25,000 miles, and it turns once on its axis in 24 hours, which is the length of the day. If the earth were thus spinning in the atmosphere, the latter not being in motion, the wind would blow with ten times hurricane velocity. The friction would be so great that nothing but the foundation rocks of the earth's crust could withstand it, and the velocity of rotation would be reduced appreciably in a relatively short time. The air [Pg 41] moves along with the earth as a part of it, and consequently no such frictional destruction takes place, but the earth rotates in the ether with that same rate, and if the ether offered resistance it would react so as to retard the rotation and increase the length of the day. Astronomical observations show that the length of the day has certainly not changed so much as the tenth of a second during the past 2000 years. The earth also revolves about the sun, having a speed of about 19 miles in a second, or 68,000 miles an hour. This motion of the earth and the other planets about the sun is one of the most stable phenomena we know. The mean distance and period of revolution of every planet is unalterable in the long run. If the earth had been retarded by its friction in the ether the length of the year would have been changed, and astronomers would have discovered it. They assert that a change in the length of a year by so much as the hundredth part of a second has not happened during the past thousand years. This then is testimony, that a velocity of nineteen miles a second for a thousand years has produced no effect upon the earth's motion that is noticeable. Nineteen miles a second is not a very swift astronomical motion, for comets have been known to have a velocity of 400 miles a second when in the neighbourhood of the sun, and yet they have not [Pg 42] seemed to suffer any retardation, for their orbits have not been shortened. Some years ago a comet was noticed to have its periodic time shortened an hour or two, and the explanation offered at first was that the shortening was due to friction in the ether although no other comet was thus affected. The idea was soon abandoned, and to-day there is no astronomical evidence that bodies having translatory motion in the ether meet with any frictional resistance whatever. If a stone could be thrown in interstellar space with a velocity of fifty feet a second it would continue to move in a straight line with the same speed for any assignable time.
As has been said, light moves with the velocity of 186,000 miles per second, and it may pursue its course for tens of thousands of years. There is no evidence that it ever loses either its wave-length or energy. It is not transformed as friction would transform it, else there would be some distance at which light of given wave-length and amplitude would be quite extinguished. The light from distant stars would be different in character from that coming from nearer stars. Furthermore, as the whole solar system is drifting in space some 500,000,000 of miles in a year, new stars would be coming into view in that direction, and faint stars would be dropping out of sight in the opposite [Pg 43] direction—a phenomenon which has not been observed. Altogether the testimony seems conclusive that the ether is a frictionless medium, and does not transform mechanical motion into heat.
That is, its properties are not alike in all directions. Chemical phenomena, crystallization, magnetic and electrical phenomena show each in their way that the properties of atoms are not alike on opposite faces. Atoms combine to form molecules, and molecules arrange themselves in certain definite geometric forms such as cubes, tetrahedra, hexagonal prisms and stellate forms, with properties emphasized on certain faces or ends. Thus quartz will twist a ray of light in one direction or the other, depending upon the arrangement which may be known by the external form of the crystal. Calc spar will break up a ray of light into two parts if the light be sent through it in certain directions, but not if in another. Tourmaline polarizes light sent through its sides and becomes positively electrified at one end while being heated. Some substances will conduct sound or light or heat or electricity better in one direction than in another. All matter is magnetic in some degree, and that implies polarity. If one will recall the structure of a vortex-ring, he will see how all the [Pg 44] motion is inward on one side and outward on the other, which gives different properties to the two sides: a push away from it on one side and a pull toward it on the other.
That is, its properties are alike in every direction. There is no distinction due to position. A mass of matter will move as freely in one direction as in another; a ray of light of any wave-length will travel in it in one direction as freely as in any other; neither velocity nor direction are changed by the action of the ether alone.
When the elements combine to form molecules they always combine in definite ways and in definite proportions. Carbon will combine with hydrogen, but will drop it if it can get oxygen. Oxygen will combine with iron or lead or sodium, but cannot be made to combine with fluorine. No more than two atoms of oxygen can be made to unite with one carbon atom, nor more than one hydrogen with one chlorine atom. There is thus an apparent choice for the kind and number of associates in molecular structure, and the instability of a molecule depends altogether upon the presence in its neighbourhood of other atoms for which some of the [Pg 45] elements in the molecule have a stronger attraction or affinity than they have for the atoms they are now combined with. Thus iron is not stable in the presence of water molecules, and it becomes iron oxide; iron oxide is not stable in the presence of hot sulphur, it becomes an iron sulphide. All the elements are thus selective, and it is by such means that they may be chemically identified.
There is no phenomenon in the ether that is comparable with this. Evidently there could not be unless there were atomic structures having in some degree different characteristics which we know the ether to be without.
It is possible to arrange the elements in the order of their atomic weights in columns which will show communities of property. Newlands, Mendeléeff, Meyer, and others have done this. The explanation for such an arrangement has not yet been forthcoming, but that it expresses a real fact is certain, for in the original scheme there were several gaps representing undiscovered elements, the properties of which were predicted from that of their associates in the table. Some of these have since been discovered, and their atomic weight and physical properties accord with those predicted.
With the ether such a scheme is quite impossible, for the very evident reason that there are no different things to have relation with each other. Every part is just like every other part. Where there are no differences and no distinctions there can be no relations. The ether is quite harmonic without relations.
So long as the atoms of matter were regarded as hard round particles, they were assumed to be inert and only active when acted upon by what were called forces, which were held to be entities of some sort, independent of matter. These could pull or push it here or there, but the matter was itself incapable of independent activity. All this is now changed, and we are called upon to consider every atom as being itself a form of energy in the same sense as heat or light are forms of energy, the energy being embodied in particular forms of motion. Light, for instance, is a wave motion of the ether. An atom is a rotary ring of ether. Stop the wave motion, and the light would be annihilated. Stop the rotation, and the atom would be annihilated for the same reason. As the ray of light is a particular embodiment of energy, and has no existence apart from it, so an atom is to be regarded as an embodiment of energy. On a [Pg 47] previous page it is said that energy is the ability of one body to act upon and move another in some degree. An atom of any kind is not the inert thing it has been supposed to be, for it can do something. Even at absolute zero, when all its vibratory or heat energy would be absent, it would be still an elastic whirling body pulling upon every other atom in the universe with gravitational energy, twisting other atoms into conformity with its own position with its magnetic energy; and, if such ether rings are like the rings which are made in air, will not stand still in one place even if no others act upon it, but will start at once by its own inherent energy to move in a right line at right angles to its own plane and in the direction of the whirl inside the ring. Two rings of wood or iron might remain in contact with each other for an indefinite time, but vortex-rings will not, but will beat each other away as two spinning tops will do if they touch ever so gently. If they do not thus separate it is because there are other forms of energy acting to press them together, but such external pressure will be lessened by the rings' own reactions.
It is true that in a frictionless medium like the ether one cannot at present see how such vortex-rings could be produced in it. Certainly not by any such mechanical methods as are employed to [Pg 48] make smoke-rings in air, for the friction of the air is the condition for producing them. However they came to be, there is implied the previous existence of the ether and of energy in some form capable of acting upon it in a manner radically different from any known in physical science.
There is good spectroscopic evidence that in some way elements of different kinds are now being formed in nebulæ, for the simplest show the presence of hydrogen alone. As they increase in complexity other elements are added, until the spectrum exhibits all the elements we know of. It has thus seemed likely either that most of what are called elements are composed of molecular groupings of some fundamental element, which by proper physical methods might be decomposed, as one can now decompose a molecule of ammonia or sulphuric acid, or that the elements are now being created by some extra-physical process in those far-off regions. In either case an atom is the embodiment of energy in such a form as to be permanent under ordinary physical circumstances, but of which, if in any manner it should be destroyed, only the form would be lost. The ether would remain, and the energy which was embodied would be distributed in other ways.
The distinction between energy in matter and energy in the ether will be apparent, on considering that both the ether and energy in some form must be conceived as existing independent of matter; though every atom were annihilated, the ether would remain and all the energy embodied in the atoms would be still in existence in the ether. The atomic energy would simply be dissolved. One can easily conceive the ether as the same space-filling, continuous, unlimited medium, without an atom in it. On this assumption it is clear that no form of energy with which we have to deal in physical science would have any existence in the ether; for every one of those forms, gravitational, thermal, electric, magnetic, or any other—all are the results of the forms of energy in matter. If there were no atoms, there would be no gravitation, for that is the attraction of atoms upon each other. If there were no atoms, there could be no atomic vibration, therefore no heat, and so on for each and all. Nevertheless, if an atom be the embodiment of energy, there must have been energy in the ether before any atom existed. One of the properties of the ether is its ability to distribute energy in certain ways, but there is no evidence that of itself it ever transforms energy. Once a [Pg 50] given kind of energy is in it, it does not change; hence for the apparition of a form of energy, like the first vortex-ring, there must have been not only energy, but some other agency capable of transforming that energy into a permanent structure. To the best of our knowledge to-day, the ether would be absolutely helpless. Such energy as was active in forming atoms must be called by another name than what is appropriate for such transformations as occur when, for instance, the mechanical energy of a bullet is transformed into heat when the target is struck. Behind the ether must be assumed some agency, directing and controlling energy in a manner totally different from any agency, which is operative in what we call physical science. Nothing short of what is called a miracle will do—an event without a physical antecedent in any way necessarily related to its factors, as is the fact of a stone related to gravity or heat to an electric current.
Ether energy is an endowment instead of being an embodiment, and implies antecedents of a super-physical kind.
As each different kind of energy represents some specific form of motion, and vice versâ, some sort of mechanism is needful for transforming one kind [Pg 51] into another, therefore molecular structure of one kind or another is essential. The transformation is a mechanical process, and matter in some particular and appropriate form is the condition of its taking place. If heat appears, then its antecedent has been some other form of motion acting upon the substance heated. It may have been the mechanical motion of another mass of matter, as when a bullet strikes a target and becomes heated; or it may be friction, as when a car-axle heats when run without proper oiling to reduce friction; or it may be condensation, as when tinder is ignited by condensing the air about it; or chemical reactions, when molecular structure is changed as in combustion, or an electrical current, which implies a dynamo and steam-engine or water-power. If light appears, its antecedent has been impact or friction, condensation or chemical action, and if electricity appears the same sort of antecedents arc present. Whether the one or the other of these forms of energy is developed, depends upon what kind of a structure the antecedent energy has acted upon. If radiant energy, so-called, falls upon a mass of matter, what is absorbed is at once transformed into heat or into electric or magnetic effects; which one of these depends upon the character of the mechanism upon which the radiant energy acts, but the radiant energy itself, which consists of [Pg 52] ether-waves, is traceable back in every case to a mass of matter having definite characteristic motions.
One may therefore say with certainty that every physical phenomenon is a change in the direction, or velocity, or character, of the energy present, and such change has been produced by matter acting as a transformer.
It has already been said that the absence of friction in the ether enables light-waves to maintain their identity for an indefinite time, and to an indefinitely great distance. In a uniform, homogeneous substance of any kind, any kind of energy which might be in it would continue in it without any change. Uniformity and homogeneity imply similarity throughout, and the necessary condition for transformation is unlikeness. One might not look for any kind of physical phenomenon which was not due to the presence and activity of some heterogeneity.
As a ray of light continues a ray of light so long as it exists in free ether, so all kinds of radiations, of whatever wave-length, continue identical until they fall upon some mechanical structure called matter. Translatory motion continues translatory, rotary continues rotary, and vibratory continues [Pg 53] to be vibratory, and no transforming change can take place in the absence of matter. The ether is helpless.
It is commonly stated that certain substances, like putty and dough, are inelastic, while some other substances, like glass, steel, and wood, are elastic. This quality of elasticity, as manifested in such different degrees, depends upon molecular combinations; some of which, as in glass and steel, are favourable for exhibiting it, while others mask it, for the ultimate atoms of all kinds are certainly highly elastic.
The measure of elasticity in a mass of matter is the velocity with which a wave-motion will be transmitted through it. Thus the elasticity of the air determines the velocity of sound in it. If the air be heated, the elasticity is increased and the sound moves faster. The rates of such sound-conduction range from a few feet in a second to about 16,000, five times swifter than a cannon ball. In such elastic bodies as vibrate to and fro like the prongs of a tuning-fork, or give sounds of a definite pitch, the rate of vibration is determined by the size and shape of the body as well as by their elementary composition. The smaller a body is, the higher its vibratory rate, if it be made of the same material [Pg 54] and the form remains the same. Thus a tuning-fork, that may be carried in the waistcoat-pocket, may vibrate 500 times a second. If it were only the fifty-millionth of an inch in size, but of the same material and form, it would vibrate 30,000,000000 times a second; and if it were made of ether, instead of steel, it would vibrate as many times faster as the velocity of waves in the ether is greater than it is in steel, and would be as many as 400,000000,000000 times per second. The amount of displacement, or the amplitude of vibration, with the pocket-fork might be no more than the hundredth of an inch, and this rate measured as translation velocity would be but five inches per second. If the fork were of atomic magnitude, and should swing its sides one half the diameter of the atom, or say the hundred-millionth of an inch, the translational velocity would be equivalent to about eighty miles a second, or a hundred and fifty times the velocity of a cannon ball, which may be reckoned at about 3000 feet.
That atoms really vibrate at the above rate per second is very certain, for their vibrations produce ether-waves the length of which may be accurately measured. When a tuning-fork vibrates 500 times a second, and the sound travels 1100 feet in the same interval, the length of each wave will be found by dividing the velocity in the air by the number of vibrations, or 1100 ÷ 500 = 2.2 feet. In like manner, [Pg 55] when one knows the velocity and wave-length, he may compute the number of vibrations by dividing the velocity by the wave-length. Now the velocity of the waves called light is 186,000 miles a second, and a light-wave may be one forty thousandth of an inch long. The atom that produces the wave must be vibrating as many times per second as the fifth thousandth of an inch is contained in 186,000 miles. Reducing this number to inches we have
|186,000 × 5280 × 12|
||= 400,000,000,000,000, nearly.|
This shows that the atoms are minute elastic bodies that change their form rapidly when struck. As rapid as the change is, yet the rate of movement is only one-fifth that of a comet when near the sun, and is therefore easily comparable with other velocities observed in masses of matter.
These vibratory motions, due to the elasticity of the atoms, is what constitutes heat.
The elasticity of a mass of matter is its ability to recover its original form after that form has been distorted. There is implied that a stress changes its shape and dimensions, which in turn implies a limited mass and relative change of position of [Pg 56] parts and some degree of discontinuity. From what has been said of the ether as being unlimited, continuous, and not made of atoms or molecules, it will be seen how difficult, if not impossible, it is to conceive how such a property as elasticity, as manifested in matter, can be attributed to the ether, which is incapable of deformation, either in structure or form, the latter being infinitely extended in every direction and therefore formless. Nevertheless, certain forms of motion, such as light-waves, move in it with definite velocity, quite independent of how they originate. This velocity of 186,000 miles a second so much exceeds any movement of a mass of matter that the motions can hardly be compared. Thus if 400 miles per second be the swiftest speed of any mass of matter known—that of a comet near the sun—the ether-wave moves 186,000 ÷ 400 = 465 times faster than such comet, and 900,000 times faster than sound travels in air. It is clear that if this rate of motion depends upon elasticity, the elasticity must be of an entirely different type from that belonging to matter, and cannot be defined in any such terms as are employed for matter.
If one considers gravitative phenomena, the difficulty is enormously increased. The orbit of a planet is never an exact ellipse, on account of the perturbations produced by the planetary attractions—perturbations which depend upon the direction [Pg 57] and distance of the attracting bodies. These, however, are so well known that slight deviations are easily noticed. If gravitative attraction took any such appreciable time to go from one astronomical body to another as does light, it would make very considerable differences in the paths of the planets and the earth. Indeed, if the velocity of gravitation were less than a million times greater than that of light, its effects would have been discovered long ago. It is therefore considered that the velocity of gravitation cannot be less than 186000,000000 miles per second. How much greater it may be no one can guess. Seeing that gravitation is ether-pressure, it does not seem probable that its velocity can be infinite. However that may be, the ability of the ether to transmit pressure and various disturbances, evidently depends upon properties so different from those that enable matter to transmit disturbances that they deserve to be called by different names. To speak of the elasticity of the ether may serve to express the fact that energy may be transmitted at a finite rate in it, but it can only mislead one's thinking if he imagines the process to be similar to energy transmission in a mass of matter. The two processes are incomparable. No other word has been suggested, and perhaps it is not needful for most scientific purposes that another should be [Pg 58] adopted, but the inappropriateness of the one word for the different phenomena has long been felt.
This quality is exhibited in two ways in matter. In the first, the different elements in their atomic form have different masses or atomic weights. An atom of oxygen weighs sixteen times as much as an atom of hydrogen; that is, it has sixteen times as much matter, as determined by weight, as the hydrogen atom has, or it takes sixteen times as many hydrogen atoms to make a pound as it takes of oxygen atoms. This is generally expressed by saying that oxygen has sixteen times the density of hydrogen. In like manner, iron has fifty-six times the density, and gold one hundred and ninety-six. The difference is one in the structure of the atomic elements. If one imagines them to be vortex-rings, they may differ in size, thickness, and rate of rotation; either of these might make all the observed difference between the elements, including their density. In the second way, density implies compactness of molecules. Thus if a cubic foot of air be compressed until it occupies but half a cubic foot, each cubic inch will have twice as many molecules in it as at first. The amount of air per unit volume will have been doubled, the weight will have been doubled, the amount of [Pg 59] matter as determined by its weight will have been doubled, and consequently we say its density has been doubled.
If a bullet or a piece of iron be hammered, the molecules are compacted closer together, and a greater number can be got into a cubic inch when so condensed. In this sense, then, density means the number of molecules in a unit of space, a cubic inch or cubic centimeter. There is implied in this latter case that the molecules do not occupy all the available space, that they may have varying degrees of closeness; in other words, matter is discontinuous, and therefore there may be degrees in density.
It is common to have the degree of density of the ether spoken of in the same way, and for the same reason, that its elasticity is spoken of. The rate of transmission of a physical disturbance, as of a pressure or a wave-motion in matter, is conditioned by its degree of density; that is, the amount of matter per cubic inch as determined by its weight; the greater the density the slower the rate. So if rate of speed and elasticity be known, the density may be computed. In this way the density of the ether has been deduced by noting the velocity of light. The enormous velocity is supposed to prove that its density is very [Pg 60] small, even when compared with hydrogen. This is stated to be about equal to that of the air at the height of two hundred and ten miles above the surface of the earth, where the air molecules are so few that a molecule might travel for 60,000,000 miles without coming in collision with another molecule. In air of ordinary density, a molecule can on the average move no further than about the two-hundred-and-fifty-thousandth of an inch without such collision. It is plain the density of the ether is so far removed from the density of anything we can measure, that it is hardly comparable with such things. If, in addition, one recalls the fact that the ether is homogeneous, that is all of one kind, and also that it is not composed of atoms and molecules, then degree of compactness and number of particles per cubic inch have no meaning, and the term density, if used, can have no such meaning as it has when applied to matter. There is no physical conception gained from the study of matter that can be useful in thinking of it. As with elasticity, so density is inappropriately applied to the ether, but there is no substitute yet offered.
So long as heat was thought to be some kind of an imponderable thing, which might retain its [Pg 61] identity whether it were in or out of matter, its real nature was obscured by the name given to it. An imponderable was a mysterious something like a spirit, which was the cause of certain phenomena in matter. Heat, light, electricity, magnetism, gravitation, were due to such various agencies, and no one concerned himself with the nature of one or the other. Bacon thought that heat was a brisk agitation of the particles of substances, and Count Rumford and Sir Humphrey Davy thought they proved that it could be nothing else, but they convinced nobody. Mayer in Germany and Joule in England showed that quantitative relations existed between work done and heat developed, but not until the publication of the book called Heat as a Mode of Motion, was there a change of opinion and terminology as to the nature of heat. For twenty years after that it was common to hear the expressions heat, and radiant heat, to distinguish between phenomena in matter and what is now called radiant energy radiations, or simply ether-waves. Not until the necessity arose for distinguishing between different forms of energy, and the conditions for developing them, did it become clear to all that a change in the form of energy implied a change in the form of motion that embodied it. The energy called heat energy was proved to be a vibratory motion of molecules, and what happened [Pg 62] in the ether as a result of such vibrations is no longer spoken of as heat, but as ether waves. When it is remembered that the ultimate atoms are elastic bodies, and that they will, if free, vibrate in a periodic manner when struck or shaken in any way, just as a ball will vibrate after it is struck, it is easy to keep in mind the distinction between the mechanical form of motion spent in striking and the vibratory form of the motion produced by it. The latter is called heat; no other form of motion than that is properly called heat. It is this alone that represents temperature, the rate and amplitude of such atomic and molecular vibrations as constitute change, of form. Where molecules like those in a gas have some freedom of movement between impacts, they bound away from each other with varying velocities. The path of such motion may be long or short, depending upon the density or compactness of the molecules, but such changes in position are not heat for a molecule any more than the flight of a musket ball is heat, though it may be transformed into heat on striking the target.
This conception of heat as the rapid change in the form of atoms and molecules, due to their elasticity, is a phenomenon peculiar to matter. It implies a body possessing form that may be changed; elasticity, that its changes may be periodic, and [Pg 63] degrees of freedom that secure space for the changes. Such a body may be heated. Its temperature will depend upon the amplitude of such vibrations, and will be limited by the maximum amplitude.
The translatory motion of a mass of matter, big or little, through the ether, is not arrested in any degree so far as observed, but the internal vibratory motion sets up waves in the ether, the ether absorbs the energy, and the amplitude is continually lessened. The motion has been transferred and transformed; transferred from matter to the ether, and transformed from vibratory to waves travelling at the rate of 186,000 miles per second. The latter is not heat, but the result of heat. With the ether constituted as described, such vibratory motion as constitutes heat is impossible to it, and hence the characteristic of heat-motion in it is impossible; it cannot therefore be heated. The space between the earth and the sun may have any assignable amount of energy in the form of ether waves or light, but not any temperature. One might loosely say that the temperature of empty spaces was absolute zero, but that would not be quite correct, for the idea of temperature cannot properly be entertained as applicable to the ether. [Pg 64] To say that its temperature was absolute zero, would serve to imply that it might be higher, which is inadmissible.
When energy has been transformed, the old name by which the energy was called must be dropped. Ether cannot be heated.
This is commonly said to be one of the essential properties of matter. All that is meant by it, however, is simply this: In no physical or chemical process to which it has been experimentally subjected has there been any apparent loss. The matter experimented upon may change from a solid or liquid to a gas, or the molecular change called chemical may result in new compounds, but the weight of the material and its atomic constituents have not appreciably changed. That matter cannot be annihilated is only the converse of the proposition that matter cannot be created, which ought always to be modified by adding, by physical or chemical processes at present known. A chemist may work with a few grains of a substance in a beaker, or test-tube, or crucible, and after several solutions, precipitations, fusions and dryings, may find by final weighing that he has not lost any appreciable amount, but how much is an appreciable amount? A fragment of matter the ten-thousandth [Pg 65] of an inch in diameter has too small a weight to be noted in any balance, yet it would be made up of thousands of millions of atoms. Hence if, in the processes to which the substance had been subjected, there had been the total annihilation of thousands of millions of atoms, such phenomenon would not have been discovered by weighing. Neither would it have been discovered if there had been a similar creation or development of new matter. All that can be asserted concerning such events is, that they have not been discovered with our means of observation.
The alchemists sought to transform one element into another, as lead into gold. They did not succeed. It was at length thought to be impossible, and the attempt to do it an absurdity. Lately, however, telescopic observation of what is going on in nebulæ, which has already been referred to, has somewhat modified ideas of what is possible and impossible in that direction. It is certainly possible roughly to conceive how such a structure as a vortex-ring in the ether might be formed. With certain polarizing apparatus it is possible to produce rays of circularly polarized light. These are rays in which the motion is an advancing rotation like the wire in a spiral spring. If such a line of rotations in the ether were flexible, and the two ends should come together, there is reason for [Pg 66] thinking they would weld together, in which case the structure would become a vortex-ring and be as durable as any other. There is reason for believing, also, that somewhat similar movements are always present in a magnetic field, and though we do not know how to make them close up in the proper way, it does not follow that it is impossible for them to do so.
The bearing of all this upon the problem of the transmutation of elements is evident. No one now will venture to deny its possibility as strongly as it was denied a generation ago. It will also lead one to be less confident in the theory that matter is indestructible. Assuming the vortex-ring theory of atoms to be true, if in any way such a ring could be cut or broken, there would not remain two or more fragments of a ring or atom. The whole would at once be dissolved into the ether. The ring and rotary energy that made it an atom would be destroyed, but not the substance it was made of, nor the energy which was embodied therein. For a long time philosophers have argued, and commonsense has agreed with them, that an atom which could not be ideally broken into two parts was impossible, that one could at any rate think of half an atom as a real objective possibility. This vortex-ring theory shows easily how possible it is to-day to think what once was philosophically incredible. It shows that [Pg 67] metaphysical reasoning may be ever so clear and apparently irrefragable, yet for all that it may be very unsound. The trouble does not come so much from the logic as from the assumption upon which the logic is founded. In this particular case the assumption was that the ultimate particles of matter were hard, irrefragable somethings, without necessary relations to anything else, or to energy, and irrefragable only because no means had been found of breaking them.
The destructibility or indestructibility of the ether cannot be considered from the same standpoint as that for matter, either ideally or really. Not ideally, because we are utterly without any mechanical conceptions of the substance upon which one can base either reason or analogy; and not really, because we have no experimental evidence as to its nature or mode of operation. If it be continuous, there are no interspaces, and if it be illimitable there is no unfilled space anywhere. Furthermore, one might infer that if in any way a portion of the ether could be annihilated, what was left would at once fill up the vacated space, so there would be no record left of what had happened. Apparently, its destruction would be the destruction of a substance, which is a very different thing from the destruction of a mode of motion. In the latter, only the form of the motion need be destroyed to [Pg 68] completely obliterate every trace of the atom. In the former, there would need to be the destruction of both substance and energy, for it is certain, for reasons yet to be attended to, that the ether is saturated with energy.
One may, without mechanical difficulties, imagine a vortex-ring destroyed. It is quite different with the ether itself, for if it were destroyed in the same sense as the atom of matter, it would be changed into something else which is not ether, a proposition which assumes the existence of another entity, the existence for which is needed only as a mechanical antecedent for the other. The same assumption would be needed for this entity as for the ether, namely, something out of which it was made, and this process of assuming antecedents would be interminable. The last one considered would have the same difficulties to meet as the ether has now. The assumption that it was in some way and at some time created is more rational, and therefore more probable, than that it either created itself or that it always existed. Considered as the underlying stratum of matter, it is clear that changes of any kind in matter can in no way affect the quantity of ether.
The resistance that a mass of matter opposes to a change in its position or rate and direction of movement, is called inertia. That it should actively oppose anything has been already pointed out as reason for denying that matter is inert, but inertia is the measure of the reaction of a body when it is acted upon by pressure from any source tending to disturb its condition of either rest or motion. It is the equivalent of mass, or the amount of matter as measured by gravity, and is a fixed quantity; for inertia is as inherent as any other quality, and belongs to the ultimate atoms and every combination of them. It implies the ability to absorb energy, for it requires as much energy to bring a moving body to a standstill as was required to give it its forward motion.
Both rotary and vibratory movements are opposed by the same property. A grindstone, a tuning-fork, and an atom of hydrogen require, to move them in their appropriate ways, an amount of energy proportionate to their mass or inertia, which energy is again transformed through friction into heat and radiated away.
One may say that inertia is the measure of the ability of a body to transfer or transform mechanical energy. The meteorite that falls upon [Pg 70] the earth to-day gives, on its impact, the same amount of energy it would have given if it had struck the earth ten thousand years ago. The inertia of the meteor has persisted, not as energy, but as a factor of energy. We commonly express the energy of a mass of matter by mv2/2, where m stands for the mass and v for its velocity. We might as well, if it were as convenient, substitute inertia for mass, and write the expression iv2/2, for the mass, being measured by its inertia, is only the more common and less definitive word for the same thing. The energy of a mass of matter is, then, proportional to its inertia, because inertia is one of its factors. Energy has often been treated as if it were an objective thing, an entity and a unity; but such a conception is evidently wrong, for, as has been said before, it is a product of two factors, either of which may be changed in any degree if the other be changed inversely in the same degree. A cannon ball weighing 1000 pounds, and moving 100 feet per second, will have 156,000 foot-pounds of energy, but a musket ball weighing an ounce will have the same amount when its velocity is 12,600 feet per second. Nevertheless, another body acting upon either bullet or cannon ball, tending to move either in some new [Pg 71] direction, will be as efficient while those bodies are moving at any assignable rate as when they are quiescent, for the change in direction will depend upon the inertia of the bodies, and that is constant.
The common theory of an inert body is one that is wholly passive, having no power of itself to move or do anything, except as some agency outside itself compels it to move in one way or another, and thus endows it with energy. Thus a stone or an iron nail are thought to be inert bodies in that sense, and it is true that either of them will remain still in one place for an indefinite time and move from it only when some external agency gives them impulse and direction. Still it is known that such bodies will roll down hill if they will not roll up, and each of them has itself as much to do with the down-hill movement as the earth has; that is, it attracts the earth as much as the earth attracts it. If one could magnify the structure of a body until the molecules became individually visible, every one of them would be seen to be in intense activity, changing its form and relative position an enormous number of times per second in undirected ways. No two such molecules move in the same way at the same time, and as all the molecules cohere together, their motions in different directions balance each other, so that the body as a whole does not change its position, [Pg 72] not because there is no moving agency in itself, but because the individual movements are scattering, and not in a common direction. An army may remain in one place for a long time. To one at a distance it is quiescent, inert. To one in the camp there is abundant sign of activity, but the movements are individual movements, some in one direction and some in another, and often changing. The same army on the march has the same energy, the same rate of individual movement; but all have a common direction, it moves as a whole body into new territory. So with the molecules of matter. In large masses they appear to be inert, and to do nothing, and to be capable of doing nothing. That is only due to the fact that their energy is undirected, not that they can do nothing. The inference that if quiescent bodies do not act in particular ways they are inert, and cannot act in any kind of a way, is a wrong inference. An illustration may perhaps make this point plainer. A lump of coal will be still as long as anything if it be undisturbed. Indeed, it has thus lain in a coal-bed for millions of years probably, but if coal be placed where it can combine with oxygen, it forthwith does so, and during the process yields a large amount of energy in the shape of heat. One pound of coal in this way gives out 14,000 heat units, which is the equivalent of 11,000,000 foot-pounds [Pg 73] of work, and if it could be all utilized would furnish a horse-power for five and a half hours. Can any inert body weighing a pound furnish a horse-power for half a day? And can a body give out what it has not got? Are gunpowder and nitro-glycerine inert? Are bread and butter and foods in general inert because they will not push and pull as a man or a horse may? All have energy, which is available in certain ways and not in others, and whatever possesses energy available in any way is not an ideally inert body. Lastly, how many inert bodies together will it take to make an active body? If the question be absurd, then all the phenomena witnessed in bodies, large or small, are due to the fact that the atoms are not inert, but are immensely energetic, and their inertia is the measure of their rates of exchanging energy.
A moving mass of matter is brought to rest by friction, because it imparts its motion at some rate to the body it is in contact with. Generally the energy is transformed into heat, but sometimes it appears as electrification. Friction is only possible because one or both of the bodies possess inertia. That a body may move in the ether for an indefinite time without losing its velocity has been [Pg 74] stated as a reason for believing the ether to be frictionless. If it be frictionless, then it is without inertia, else the energy of the earth and of a ray of light would be frittered away. A ray of light can only be transformed when it falls upon molecules which may be heated by it. As the ether cannot be heated and cannot transform translational energy, it is without inertia for such a form of motion and its embodied energy.
It is not thus with other forms of energy than the translational. Atomic and molecular vibrations are so related to the ether that they are transformed into waves, which are conducted away at a definite rate. This shows that such property of inertia as is possessed by the ether is selective and not like that of matter, which is equally “inertiative” under all conditions. Similarly with electric and magnetic phenomena, it is capable of transforming the energy which may reside as stress in the ether, and other bodies moving in the space so affected meet with frictional resistance, for they become heated if the motion be maintained. On the other hand, there is no evidence that the body which produced the electric or magnetic stress suffers any degree of friction on moving in precisely the same space. A bar magnet rotating on its longitudinal axis does not disturb its own field, but a piece [Pg 75] of iron revolving near the magnet will not only become heated, but will heat the stationary magnet. Much experimental work has been done to discover, if possible, the relation of a magnet to its ether field. As the latter is not disturbed by the rotation of the magnet, it has been concluded that the field does not rotate; but as every molecule in the magnet has its own field independent of all the rest, it is mechanically probable that each such field does vary in the rotation, but among the thousands of millions of such fields the average strength of the field does not vary within measurable limits. Another consideration is that the magnetic field itself, when moved in space, suffers no frictional resistance. There is no magnetic energy wasted through ether inertia. These phenomena show that whether the ether exhibits the quality called inertia depends upon the kind of motion it has.
The ordinary phenomenon of magnetism is shown by bringing a piece of iron into the neighbourhood of a so-called magnet, where it is attracted by the latter, and if free to move will go to and cling to the magnet. A delicately suspended magnetic needle will be affected appreciably by a strong magnet at the distance of several hundred [Pg 76] feet. As the strength of such action varies inversely as the square of the distance from the magnet, it is evident there can be no absolute boundary to it. At a distance from an ordinary magnet it becomes too weak to be detected by our methods, not that there is a limit to it. It is customary to think of iron as being peculiarly endowed with magnetic quality, but all kinds of matter possess it in some degree. Wood, stone, paper, oats, sulphur, and all the rest, are attracted by a magnet, and will stick to it if the magnet be a strong one. Whether a piece of iron itself exhibits the property depends upon its temperature, for near 700 degrees it becomes as magnetically indifferent as a piece of copper at ordinary temperature. Oxygen, too, at 200 degrees below the zero of Centigrade adheres to a magnet like iron.
In this as in so many other particulars, how a piece of matter behaves depends upon its temperature, not that the essential qualities are modified in any degree, but temperature interferes with atomic arrangement and aggregation, and so disguises their phenomena.
As every kind of matter is thus affected by a magnet, the manifestations differing but in degree, it follows that all kinds of atoms—all the elements—are magnetic. An inherent property in them, as much so as gravitation or inertia; apparently a [Pg 77] quality depending upon the structure of the atoms themselves, in the same sense as gravitation is thus dependent, as it is not a quality of the ether.
An atom must, then, be thought of as having polarity, different qualities on the two sides, and possessing a magnetic field as extensive as space itself. The magnetic field is the stress or pressure in the ether produced by the magnetic body. This ether pressure produced by a magnet may be as great as a ton per square inch. It is this pressure that holds an armature to the magnet. As heat is a molecular condition of vibration, and radiant energy the result of it, so is magnetism a property of molecules, and the magnetic field the temporary condition in the ether, which depends upon the presence of a magnetic body. We no longer speak of the wave-motion in the ether which results from heat, as heat, but call it radiation, or ether waves, and for a like reason the magnetic field ought not to be called magnetism.
A magnetic field manifests itself in a way that implies that the ether structure, if it may be said to have any, is deformed—deformed in such a sense that another magnet in it tends to set itself in the plane of the stress; that is, the magnet is twisted into a new position to accommodate itself to the condition [Pg 78] of the medium about it. The new position is the result of the reaction of the ether upon the magnet and ether pressure acting at right angles to the body that produced the stress. Such an action is so anomalous as to suggest the propriety of modifying the so-called third law of motion, viz., action and reaction are equal and opposite, adding that sometimes action and reaction are at right angles.
There is no condition or property exhibited by the ether itself which shows it to have any such characteristic as attraction, repulsion, or differences in stress, except where its condition is modified by the activities of matter in some way. The ether itself is not attracted or repelled by a magnet; that is, it is not a magnetic body in any such sense as matter in any of its forms is, and therefore cannot properly be called magnetic.
It has been a mechanical puzzle to understand how the vibratory motions called heat could set up light waves in the ether seeing that there is an absence of friction in the latter. In the endeavour to conceive it, the origin of sound-waves has been in mind, where longitudinal air-waves are produced by the vibrations of a sounding body, and molecular impact is the antecedent of the waves. The analogy does not apply. The following exposition may be helpful in grasping the idea of such transformation and change of energy from matter to the ether.
Consider a straight bar permanent magnet to be held in the hand. It has its north and south poles and its field, the latter extending in every direction to an indefinite distance. The field is to be considered as ether stress of such a sort as to tend to set other magnets in it in new positions. If at a distance of ten feet there were a delicately-poised magnet needle, every change in the position of the magnet held in the hand would bring about a change in the position of the needle. If the position of the hand magnet were completely reversed, so the south pole faced where the north pole faced before, the field would have been completely reversed, and the poised needle would have been pushed by the field into an opposite position. If the needle were a hundred feet away, the change would have been the same except in amount. The same might be said if the two were a mile apart, or the distance of the moon or any other distance, for there is no limit to an ether magnetic field. Suppose the hand magnet to have its direction completely reversed once in a second. The whole field, and the direction of the stress, would necessarily be reversed as often. But this kind of change in stress is known by experiment to travel with the speed of light, 186,000 miles a second; the disturbance due to the change of position of the magnet will therefore be felt in some degree [Pg 80] throughout space. In a second and a third of a second it will have reached the moon, and a magnet there will be in some measure affected by it. If there were an observer there with a delicate-enough magnet, he could be witness to its changes once a second for the same reason one in the room could. The only difference would be one of amount of swing. It is therefore theoretically possible to signal to the moon with a swinging magnet. Suppose again that the magnet should be swung twice a second, there would be formed two waves, each one half as long as the first. If it should swing ten times a second, then the waves would be one-tenth of 186,000 miles long. If in some mechanical way it could be rotated 186,000 times a second, the wave would be but one mile long. Artificial ways have been invented for changing this magnet field as many as 100 million times a second, and the corresponding wave is less than a foot long. The shape of a magnet does not necessarily make it weaker or stronger as a magnet, but if the poles are near together the magnetic field is denser between them than when they are separated. The ether stress is differently distributed for every change in the relative positions of the poles.
A common U-magnet, if struck, will vibrate like a tuning-fork, and gives out a definite pitch. Its [Pg 81] poles swing towards and away from each other at uniform rates, and the pitch of the magnet will depend upon its size, thickness, and the material it is made of.
Let ten or fifteen ohms of any convenient-sized wire be wound upon the bend of a commercial U-magnet. Let this wire be connected to a telephone in its circuit. When the magnet is made to sound like a tuning-fork, the pitch will be reproduced in the telephone very loudly. If another magnet with a different pitch be allowed to vibrate near the former, the pitch of the vibrating body will be heard in the telephone, and these show that the changing magnetic field reacts upon the quiescent magnet, and compels the latter to vibrate at the same rate. The action is an ether action, the waves are ether waves, but they are relatively very long. If the magnet makes 500 vibrations a second, the waves will be 372 miles long, the number of times 500 is contained in 186,000 miles. Imagine the magnet to become smaller and smaller until it was the size of an atom, the one-fifty-millionth of an inch. Its vibratory rate would be proportionally increased, and changes in its form will still bring about changes in its magnetic field. But its magnetic field is practically limitless, and the number of vibrations per second is to be reckoned as millions of millions; the waves are [Pg 82] correspondingly short, small fractions of an inch. When they are as short as the one-thirty-seven-thousandth of an inch, they are capable of affecting the retina of the eye, and then are said to be visible as red light. If the vibratory rate be still higher, and the corresponding waves be no more than one-sixty-thousandth of an inch long, they affect the retina as violet light, and between these limits there are all the waves that produce a complete spectrum. The atoms, then, shake the ether in this way because they all have a magnetic hold upon the ether, so that any disturbance of their own magnetism, such as necessarily comes when they collide, reacts upon the ether for the same reason that a large magnet acts thus upon it when its poles approach and recede from each other. It is not a phenomenon of mechanical impact or frictional resistance, since neither are possible in the ether.
Molecular cohesion exists between very wide ranges. When strong, so if one part of a body is moved the whole is moved in the same way, without breaking continuity or the relative positions of the molecules, we call the body a solid. In a liquid, cohesion is greatly reduced, and any part of it may be deformed without materially changing [Pg 83] the form of the rest. The molecules are free to move about each other, and there is no definite position which any need assume or keep. With gases, the molecules are without any cohesion, each one is independent of every other one, collides with and bounds away from others as free elastic particles do. Between impacts it moves in what is called its free path, which may be long or short as the density of the gas be less or greater.
These differing degrees of cohesion depend upon temperature, for if the densest and hardest substances are sufficiently heated they will become gaseous. This is only another way of saying that the states of matter depend upon the amount of molecular energy present. Solid ice becomes water by the application of heat. More heat reduces it to steam; still more decomposes the steam molecules into oxygen and hydrogen molecules; and lastly, still more heat will decompose these molecules into their atomic state, complete dissociation. On cooling, the process of reduction will be reversed until ice has been formed again.
Cohesive strength in solids is increased by reduction of temperature, and metallic rods become stronger the colder they are.
No distinction is now made between cohesion and chemical affinity, and yet at low temperatures chemical action will not take place, which [Pg 84] phenomenon shows there is a distinction between molecular cohesion and molecular structure. In molecular structure, as determined by chemical activity, the molecules and atoms are arranged in definite ways which depend upon the rate of vibrations of the components. The atoms are set in definite positions to constitute a given molecule. But atoms or molecules may cohere for other reasons, gravitative or magnetic, and relative positions would be immaterial. In the absence of temperature, a solid body would be solider and stronger than ever, while a gaseous mass would probably fall by gravity to the floor of the containing vessel like so much dust. The molecular structure might not be changed, for there would be no agency to act upon it in a disturbing way.
Degrees of density have already been excluded, and the homogeneity and continuity of the ether would also exclude the possibility of different states at all comparable with such as belong to matter. As for cohesion, it is doubtful if the term ought to be applied to such a substance. The word itself seems to imply possible separateness, and if the ether be a single indivisible substance, its cohesion must be infinite and is therefore not a matter of degree. The ether has sometimes been [Pg 85] considered as an elastic solid, but such solidity is comparable with nothing we call solid in matter, and the word has to be defined in a special sense in order that its use may be tolerated at all. In addition to this, some of the phenomena exhibited by it, such as diffraction and double refraction, are quite incompatible with the theory that the ether is an elastic solid. The reasons why it cannot be considered as a liquid or gas have been considered previously.
The expression states of matter cannot be applied to the ether in any such sense as it is applied to matter, but there is one sense when possibly it may be considered applicable. Let it be granted that an atom is a vortex-ring of ether in the ether, then the state of being in ring rotation would suffice to differentiate that part of the ether from the rest, and give to it a degree of individuality not possessed by the rest; and such an atom might be called a state of ether. In like manner, if other forms of motion, such as transverse waves, circular and elliptical spirals, or others, exist in the ether, then such movements give special character to the part thus active, and it would be proper to speak of such states of the ether, but even thus the word would not be used in the same sense as it is used when one speaks of the states of matter as being solid, liquid, and gaseous.
A sliding stress applied to a solid deforms it to a degree which depends upon the stress and the degree of rigidity preserved by the body. Thus if the hand be placed upon a closed book lying on the table, and pressure be so applied as to move the upper side of the book but not the lower, the book is said to be subject to a shearing stress. If the pressing hand has a twisting motion, the book will be warped. Any solid may be thus sheared or warped, but neither liquids nor gases can be so affected. Molecular cohesion makes it possible in the one, and the lack of it, impossible in the others. The solid can maintain such a deformation indefinitely long, if the pressure does not rupture its molecular structure.
The phenomena in a magnetic field show that the stress is of such a sort as to twist into a new directional position the body upon which it acts as exhibited by a magnetic needle, also as indicated by the transverse vibrations of the ether waves, and again by the twist given to plane polarized light when moving through a magnetic field. These are [Pg 87] all interpreted as indicative of the direction of ether stress, as being similar to a shearing stress in solid matter. The fact has been adduced to show the ether to be a solid, but such a phenomenon is certainly incompatible with a liquid or gaseous ether. This kind of stress is maintained indefinitely about a permanent magnet, and the mechanical pressure which may result from it is a measure of the strength of the magnetic field, and may exceed a thousand pounds per square inch.
There are many secondary qualities exhibited by matter in some of its forms, such as hardness, brittleness, malleability, colour, etc., and the same ultimate element may exhibit itself in the most diverse ways, as is the case with carbon, which exists as lamp-black, charcoal, graphite, jet, anthracite and diamond, ranging from the softest to the hardest of known bodies. Then it may be black or colourless. Gold is yellow, copper red, silver white, chlorine green, iodine purple. The only significance any or all of such qualities have for us here is that the ether exhibits none of them. There is neither hardness nor brittleness, nor colour, nor any approach to any of the characteristics for the identification of elementary matter.
However great the mystery of the relation of body to mind, it is quite true that the nervous system is the mechanism by and through which all sensation comes, and that in our experience in the absence of nerves there is neither sensation nor consciousness. The nerves themselves are but complex chemical structures; their molecular constitution is said to embrace as many as 20,000 atoms, chiefly carbon, hydrogen, oxygen, and nitrogen. There must be continuity of this structure too, for to sever a nerve is to paralyze all beyond. If all knowledge comes through experience, and all experience comes through the nervous system, the possibilities depend upon the mechanism each one is provided with for absorbing from his environment, what energies there are that can act upon the nerves. Touch, taste, and smell imply contact, sound has greater range, and sight has the immensity of the universe for its field. The most distant but visible star acts through the optic nerve to present itself to consciousness. It is not the ego that looks out through the eyes, but it is the universe that pours in upon the ego.
Again, all the known agencies that act upon the nerves, whether for touch or sound or sight, imply matter in some of its forms and activities, to adapt [Pg 89] the energy to the nervous system. The mechanism for the perception of light is complicated. The light acts upon a sensitive surface where molecular structure is broken up, and this disturbance is in the presence of nerve terminals, and the sensation is not in the eye but in the sensorium. In like manner for all the rest; so one may fairly say that matter is the condition for sensation, and in its absence there would be nothing we call sensation.
The ether is in great contrast with matter in this particular. There is no evidence that in any direct way it acts upon any part of the nervous system, or upon the mind. It is probable that this lack of relation between the ether and the nervous system was the chief reason why its discovery was so long delayed, as the mechanical necessities for it even now are felt only by such as recognize continuity as a condition for the transmission of energy of whatever kind it may be. Action at a distance contradicts all experience, is philosophically incredible, and is repudiated by every one who once perceives that energy has two factors—substance and motion.
The table given below presents a list of twenty-two of the known properties of matter contrasted with those exhibited by the ether. In none of them [Pg 90] are the properties of the two identical, and in most of them what is true for one is not true for the other. They are not simply different, they are incomparable.
From the necessities of the case, as knowledge has been acquired and terminology became essential for making distinctions, the ether has been described in terms applicable to matter, hence such terms as mass, solidity, elasticity, density, rigidity, etc., which have a definite meaning and convey definite mechanical conceptions when applied to matter, but have no corresponding meaning and convey no such mechanical conceptions when applied to the ether. It is certain that they are inappropriate, and that the ether and its properties cannot be described in terms applicable to matter. Mathematical considerations derived from the study of matter have no advantage, and are not likely to lead us to a knowledge of the ether.
Only a few have perceived the inconsistency of thinking of the two in the same terms. In his Grammar of Science, Prof. Karl Pearson says, “We find that our sense-impressions of hardness, weight, colour, temperature, cohesion, and chemical constitution, may all be described by the aid of the motions of a single medium, which itself is conceived to have no hardness, weight, colour, temperature, nor indeed elasticity of the ordinary conceptual type.”
None of the properties of the ether are such as [Pg 91] one would or could have predicted if he had had all the knowledge possessed by mankind. Every phenomenon in it is a surprise to us, because it does not follow the laws which experience has enabled us to formulate for matter. A substance which has none of the phenomenal properties of matter, and is not subject to the known laws of matter, ought not to be called matter. Ether phenomena and matter phenomena belong to different categories, and the ends of science will not be conserved by confusing them, as is done when the same terminology is employed for both.
There are other properties belonging to the ether more wonderful, if possible, than those already mentioned. Its ability to maintain enormous stresses of various kinds without the slightest evidence of interference. There is the gravitational stress, a direct pull between two masses of matter. Between two molecules it is immeasurably small even when close together, but the prodigious number of them in a bullet brings the action into the field of observation, while between such bodies as the earth and moon or sun, the quantity reaches an astonishing figure. Thus if the gravitative tension due to the gravitative attraction of the earth and moon were to be replaced by steel wires connecting the two bodies to prevent the moon from leaving its orbit, there would be needed four [Pg 92] number ten steel wires to every square inch upon the earth, and these would be strained nearly to the breaking point. Yet this stress is not only endured continually by this pliant, impalpable, transparent medium, but other bodies can move through the same space apparently as freely as if it were entirely free. In addition to this, the stress from the sun and the more variable stresses from the planets are all endured by the same medium in the same space and apparently a thousand or a million times more would not make the slightest difference. Rupture is impossible.
Electric and magnetic stresses, acting parallel or at right angles to the other, exist in the same space and to indefinite degrees, neither modifying the direction nor amount of either of the others.
These various stresses have been computed to represent energy, which if it could be utilized, each cubic inch of space would yield five hundred horse-power. It shows what a store-house of energy the ether is. If every particle of matter were to be instantly annihilated, the universe of ether would still have an inexpressible amount of energy left. To draw at will directly from this inexhaustible supply, and utilize it for the needs of mankind, is not a forlorn hope.
The accompanying table presents these contrasting properties for convenient inspection.
|11.||Energy embodied||Energy endowed|
|20.||Subject to shearing stress in solid||Shearing stress maintained|
|21.||Has Secondary qualities|
|22.||Sensation depends upon||Insensible to nerves|
Vortex-rings for illustration may be made by having a wooden box about a foot on a side, with a round orifice in the middle of one side, and the side opposite covered with stout cloth stretched tight over a framework. A saucer containing strong ammonia water, and another containing strong hydrochloric acid, will cause dense fumes in the box, and a tap with the hand upon the cloth back will force out a ring from the orifice. These may be made to follow and strike each other, rebounding and vibrating, apparently attracting each other and being attracted by neighbouring bodies.
By filling the mouth with smoke, and pursing the lips as if to make the sound o, one may make fifteen or twenty small rings by snapping the cheek with the finger.
Antecedents of Electricity—Nature of what is transformed—Series of transformations for the production of light—Positive and negative Electricity—Positive and negative twists—Rotations about a wire—Rotation of an arc—Ether a non-conductor—Electro-magnetic waves—Induction and inductive action—Ether stress and atomic position—Nature of an electric current—Electricity a condition, not an entity.
So far as we have knowledge to-day, the only factors we have to consider in explaining physical phenomena are: (1) Ordinary matter, such as constitutes the substance of the earth, and the heavenly bodies; (2) the ether, which is omnipresent; and (3) the various forms of motion, which are mutually transformable in matter, and some of which, but not all, are transformable into ether forms. For instance, the translatory motion of a mass of matter can be imparted to another mass by simple impact, but translatory motion cannot be imparted to the ether, and, for that reason, a body moving in it is [Pg 95] not subject to friction, and continues to move on with velocity undiminished for an indefinite time; but the vibratory motion which constitutes heat is transformable into wave-motion in the ether, and is transmitted away with the speed of light. The kind of motion which is thus transformed is not even a to-and-fro swing of an atom, or molecule, like the swing of a pendulum bob, but that due to a change of form of the atoms within the molecule, otherwise there could be no such thing as spectrum analysis. Vibratory motion of the matter becomes undulatory motion in the ether. The vibratory motion we call heat; the wave-motion we call sometimes radiant energy, sometimes light. Neither of these terms is a good one, but we now have no others.
It is conceded that it is not proper to speak of the wave-motion in the ether as heat; it is also admitted that the ether is not heated by the presence of the wave—or, in other words, the temperature of the ether is absolute zero. Matter only can be heated. But the ether waves can heat other matter they may fall on; so there are three steps in the process and two transformations—(1) vibrating matter; (2) waves in the ether; (3) vibration in other matter. Energy has been transferred indirectly. What is important to bear in mind is, that when a form of energy in matter is transformed in any manner so as to lose its characteristics, it is not proper to call [Pg 96] it by the same name after as before, and this we do in all cases when the transformation is from one kind in matter to another kind in matter. Thus, when a bullet is shot against a target, before it strikes it has what we call mechanical energy, and we measure that in foot-pounds; after it has struck the target, the transformation is into heat, and this has its mechanical equivalent, but is not called mechanical energy, nor are the motions which embody it similar. The mechanical ideas in these phenomena are easy to grasp. They apply to the phenomena of the mechanics of large and small bodies, to sound, to heat, and to light, as ordinarily considered, but they have not been applied to electric phenomena, as they evidently should be, unless it be held that such phenomena are not related to ordinary phenomena, as the latter are to one another.
When we would give a complete explanation of the phenomena exhibited by, say, a heated body, we need to inquire as to the antecedents of the manifestation, and also its consequents. Where and how did it get its heat? Where and how did it lose it? When we know every step of those processes, we know all there is to learn about them. Let us undertake the same thing for some electrical phenomena.
First, under what circumstances do electrical phenomena arise?
(1) Mechanical, as when two different kinds of matter are subject to friction.
(2) Thermal, as when two substances in molecular contact are heated at the junction.
(3) Magnetic, as when any conductor is in a changing magnetic field.
(4) Chemical, as when a metal is being dissolved in any solution.
(5) Physiological, as when a muscle contracts.
Each of these has several varieties, and changes may be rung on combinations of them, as when mechanical and magnetic conditions interact.
(1) In the first case, ordinary mechanical or translational energy is spent as friction, an amount measurable in foot-pounds, and the factors we [Pg 98] know, a pressure into a distance. If the surface be of the same kind of molecules, the whole energy is spent as heat, and is presently radiated away. If the surfaces are of unlike molecules, the product is a compound one, part heat, part electrical. What we have turned into the machine we know to be a particular mode of motion. We have not changed the amount of matter involved; indeed, we assume, without specifying and without controversy, that matter is itself indestructible, and the product, whether it be of one kind or another, can only be some form of motion. Whether we can describe it or not is immaterial; but if we agree that heat [Pg 99] is vibratory molecular motion, and there be any other kind of a product than heat, it too must also be some other form of motion. So if one is to form a conception of the mechanical origin of electricity, this is the only one he can have—transformed motion.
(2) When heat is the antecedent of electricity, as in the thermo-pile, that which is turned into the pile we know to be molecular motion of a definite kind. That which comes out of it must be some equivalent [Pg 100] motion, and if all that went in were transformed, then all that came out would be transformed, call it by what name we will and let its amount be what it may.
(3) When a conductor is moved in a magnetic field, the energy spent is measurable in foot-pounds, as before, a pressure into a distance. The energy appears in a new form, but the quantity of matter being unchanged, the only changeable factor is the kind of motion, and that the motion is molecular is evident, for the molecules are heated. Mechanical or mass motion is the antecedent, molecular heat motion is the consequent, and the way we know there has been some intermediate form is, that heat is not conducted at the rate which is observed in such a case. Call it by what name one will, some form of motion has been intermediate between the antecedent and the consequent, else we have some other factor of energy to reckon with than ether, matter and motion.
(4) In a galvanic battery, the source of electricity is chemical action; but what is chemical action? Simply an exchange of the constituents of molecules—a change which involves exchange of energy. Molecules capable of doing chemical work are loaded with energy. The chemical products of battery action are molecules of different constitution, with smaller amounts of energy as [Pg 101] measured in calorics or heat units. If the results of the chemical reaction be prevented from escaping, by confining them to the cell itself, the whole energy appears as heat and raises the temperature of the cell. If a so-called circuit be provided, the energy is distributed through it, and less heat is spent in the cell, but whether it be in one place or another, the mass of matter involved is not changed, and the variable factor is the motion, the same as in the other cases. The mechanical conceptions appropriate are the transformation of one kind of motion into another kind by the mechanical conditions provided.
(5) Physiological antecedents of electricity are exemplified by the structure and mode of operation of certain muscles (Fig. 9, a) in the torpedo and other electrical animals. The mechanical contraction of them results in an electrical excitation, and, if a proper circuit be provided, in an electric current. The energy of a muscle is derived from food, which is itself but a molecular compound loaded with energy of a kind available for muscular transformation. Bread-and-butter has more available energy, pound for pound, than has coal, and can be substituted for coal for running an engine. It is not used, because it costs so much more. There is nothing different, so far as the factors of energy go, between the food of an animal and the food of an engine. What becomes of the energy depends upon the kind of structure it acts on. It may be changed into translatory, and the whole body moves in one direction; or into molecular, and then appears as heat or electrical energy.
If one confines his attention to the only variable factor in the energy in all these cases, and traces out in each just what happens, he will have only motions of one sort or another, at one rate or another, and there is nothing mysterious which enters into the processes.
We will turn now to the mode in which electricity manifests itself, and what it can do. It may [Pg 103] be well to point out at the outset what has occasionally been stated, but which has not received the philosophical attention it deserves—namely, that electrical phenomena are reversible; that is, any kind of a physical process which is capable of producing electricity, electricity is itself able to produce. Thus to name a few: If mechanical [Pg 104] motion develops electricity, electricity will produce mechanical motion; the movement of a pith ball and an electric motor are examples. If chemical action can produce it, it will produce chemical action, as in the decomposition of water and electro-plating. As heat may be its antecedent, so will it produce heat. If magnetism be an antecedent factor, magnetism may be its product. What is called induction may give rise to it in an adjacent conductor, and, likewise, induction may be its effect.
Let us suppose ourselves to be in a building in which a steam-engine is at work. There is fuel, the furnace, the boiler, the pipes, the engine with its fly-wheel turning. The fuel burns in the furnace, the water is superheated in the boiler, the steam is directed by the pipes, the piston is moved by the steam pressure, and the fly-wheel rotates [Pg 105] because of proper mechanism between it and the piston. No one who has given attention to the successive steps in the process is so puzzled as to feel the need of inventing a particular force, or a new kind of matter, or any agency, at any stage of the process, different from the simple mechanical ones represented by a push or a pull. Even if he cannot see clearly how heat can produce a push, he does not venture to assume a genii to do the work, but for the time is content with saying that if he starts with motion in the furnace and stops with the motion of the fly-wheel, any assumption of any other factor than some form of motion between the two would be gratuitous. He can truthfully say that he understands the nature of that which goes on between the furnace and the wheel; that it is some sort of motion, the particular kind of which he might make out at his leisure.
Suppose once more that, across the road from an engine-house, there was another building, where all sorts of machines—lathes, planers, drills, etc.—were running, but that the source of the power for all this was out of sight, and that one could see no connection between this and the engine on the other side of the street. Would one need to suppose there was anything mysterious between the two—a force, a fluid, an immaterial something? This question is put on the supposition that one should [Pg 106] not be aware of the shaft that might be between the two buildings, and that it was not obvious on simple inspection how the machines got their motions from the engine. No one would be puzzled because he did not know just what the intervening mechanism might be. If the boiler were in the one building, and the engine in the other with the machines, he could see nothing moving between them, even if the steam-pipes were of glass. If matter of any kind were moving, he could not see it there. He would say there must be something moving, or pressure could not be transferred from one place to the other.
Substitute for the furnace and boiler a galvanic battery or a dynamo; for the machines of the shop, one or more motors with suitable wire connections. When the dynamo goes the motors go; when the dynamo stops the motors stop; nothing can be seen to be turning or moving in any way between them. Is there any necessity for assuming a mysterious agency, or a force of a nature different from the visible ones at the two ends of the line? Is it not certain that the question is, How does the motion get from one to the other, whether there be a wire or not? If there be a wire, it is plain that there is motion in it, for it is heated its whole length, and heat is known to be a mode of motion, and every molecule which is thus heated must have had some [Pg 107] antecedent motions. Whether it be defined or not, and whether it be called by one name or another, are quite immaterial, if one is concerned only with the nature of the action, whether it be matter or ether, or motion or abracadabra.
Once more: suppose we have a series of active machines. (Fig. 11.) An arc lamp, radiating light-waves, gets its energy from the wire which is heated, which in turn gets its energy from the electric current; that from a dynamo, the dynamo from a steam-engine; that from a furnace and the chemical actions going on in it. Let us call the chemical actions a, the furnace b, the engine c, the dynamo d, the electric lamp e, the ether waves f. (Fig. 12.)
The product of the chemical action of the coal is molecular motion, called heat in the furnace. The product of the heat is mechanical motion in the engine. The product of the mechanical motion is electricity in the dynamo. The product of the electric current in the lamp is light-waves in the ether. No one hesitates for an instant to speak of the heat as being molecular motion, nor of the [Pg 108] motions of the engine as being mechanical; but when we come to the product of the dynamo, which we call electricity, behold, nearly every one says, not that he does not know what it is, but that no one knows! Does any one venture to say he does not know what heat is, because he cannot describe in detail just what goes on in a heated body, as it might be described by one who saw with a microscope the movements of the molecules? Let us go back for a moment to the proposition stated early in this book, namely, that if any body of any magnitude moves, it is because some other body in motion and in contact with it has imparted its motion by mechanical pressure. Therefore, the ether waves at f (Fig. 11) imply continuous motions of some sort from a to f. That they are all motions of ordinary matter from a to e is obvious, because continuous matter is essential for the maintenance [Pg 109] of the actions. At e the motions are handed over to the ether, and they are radiated away as light-waves.
A puzzling electrical phenomenon has been what has been called its duality-states, which are spoken of as positive and negative. Thus, we speak of the positive plate of a battery and the negative pole of a dynamo; and another troublesome condition to idealize has been, how it could be that, in an electric circuit, there could be as much energy at [Pg 110] the most remote part as at the source. But, if one will take a limp rope, 8 or 10 feet long, tie its ends together, and then begin to twist it at any point, he will see the twist move in a right-handed spiral on the one hand, and in a left-handed spiral on the other, and each may be traced quite round the circuit; so there will be as much twist, as much motion, and as much energy in one part of the rope as in any other; and if one chooses to call the right-handed twist positive, and the left-handed twist negative, he will have the mechanical phenomenon of energy-distribution and the terminology, analogous to what they are in an electric conductor. (Fig. 13.) Are the cases more dissimilar than the mechanical analogy would make them seem to be?
Are there any phenomena which imply that rotation is going on in an electric conductor? There are. An electric arc, which is a current in the air, and is, therefore, less constrained than it is in a conductor, rotates. Especially marked is this when in front of the pole of a magnet; but the rotation may be noticed in an ordinary arc by looking at it with a stroboscope disk, rotated so as to make the light to the eye intermittent at the rate of four or five hundred per second. A ray of plane polarized light, parallel with a wire conveying a current, has its plane of vibration twisted to the right or left, as the current goes [Pg 111] one way or the other through the wire, and to a degree that depends upon the distance it travels; not only so, but if the ray be sent, by reflection, back through the same field, it is twisted as much more—a phenomenon which convinces one that rotation is going on in the space through which the ray travels. If the ether through which the ray be sent were simply warped or in some static stress, the ray, after reflection, would be brought back to its original plane, which is not the case. This rotation in the ether is produced by what is going on in the wire. The ether waves called light are interpreted to imply that molecules originate them by their vibrations, and that there are as many ether waves per second as of molecular vibrations per second. In like manner, the implication is the same, that if there be rotations in the ether they must be produced by molecular rotation, and there must be as many rotations per second in the ether as there are molecular rotations that produce them. The space about a wire carrying a current is often pictured as filled with whorls indicating this motion (Fig. 14), and one must picture to himself, not the wire as a whole rotating, but each individual molecule independently. But one is aware that the molecules of a conductor are practically in contact with each other, and that if one for any reason rotates, [Pg 112] the next one to it would, from frictional action, cause the one it touched to rotate in the opposite direction, whereas, the evidence goes to show that all rotation is in the same direction.
How can this be explained mechanically? Recall the kind of action that constitutes heat, that it is not translatory action in any degree, but vibratory, in the sense of a change of form of an elastic body, and this, too, of the atoms that make up the molecule of whatever sort. Each atom is so far independent of every other atom in the molecule that it can vibrate in this way, else it could not be heated. The greater the amplitude of vibration, the more free space to move in, and continuous contact of atoms is incompatible with the mechanics of heat. There must, therefore, be impact and freedom alternating with each other in all degrees in a heated body. If, in any way, the atoms themselves were made to rotate, their heat impacts not only would restrain the rotations, but the energy also of the rotation motion would increase the vibrations; [Pg 113] that is, the heat would be correspondingly increased, which is what happens always when an electric current is in a conductor. It appears that the cooler a body is the less electric resistance it has, and the indications are that at absolute zero there is no resistance; that is, impacts do not retard rotation, but it is also apparent that any current sent through a conductor at that temperature would at once heat it. This is the same as saying that an electric current could not be sent through a conductor at absolute zero.
So far, mechanical conceptions are in accordance with electrical phenomena, but there are several others yet to be noted. Electrical phenomena has been explained as molecular or atomic phenomena, and there is one more in that category which is well enough known, and which is so important and suggestive, that the wonder is its significance has not been seen by those who have sought to interpret electrical phenomena. The reference is to the fact that electricity cannot be transmitted through a vacuum. An electric arc begins to spread out as the density of the air decreases, and presently it is extinguished. An induction spark that will jump two or three feet in air cannot be made to bridge the tenth of an inch in an ordinary vacuum. A vacuum is a perfect non-conductor of electricity. Is there more than one possible interpretation to this, [Pg 114] namely, that electricity is fundamentally a molecular and atomic phenomenon, and in the absence of molecules cannot exist? One may say, %ldquo;Electrical action is not hindered by a vacuum,” which is true, but has quite another interpretation than the implication that electricity is an ether phenomenon. The heat of the sun in some way gets to the earth, but what takes place in the ether is not heat-transmission. There is no heat in space, and no one is at liberty to say, or think, that there can be heat in the absence of matter.
When heat has been transformed into ether waves, it is no longer heat, call it by what name one will. Formerly, such waves were called heat-waves; no one, properly informed, does so now. In like manner, if electrical motions or conditions in matter be transformed, no matter how, it is no longer proper to speak of such transformed motions or conditions as electricity. Thus, if electrical energy be transformed into heat, no one thinks of speaking of the latter as electrical. If the electrical energy be transformed into mechanical of any sort, no one thinks of calling the latter electrical because of its antecedent. If electrical motions be transformed into ether actions of any kind, why should we continue to speak of the transformed motions or energy as being electrical? Electricity may be the antecedent, [Pg 115] in the same sense as the mechanical motion of a bullet may be the antecedent of the heat developed when the latter strikes the target; and if it be granted that a vacuum is a perfect non-conductor of electricity, then it is manifestly improper to speak of any phenomenon in the ether as an electrical phenomenon. It is from the failure to make this distinction that most of the trouble has come in thinking on this subject. Some have given all their attention to what goes on in matter, and have called that electricity; others have given their attention to what goes on in the ether, and have called that electricity, and some have considered both as being the same thing, and have been confounded.
Let us consider what is the relation between an electrified body and the ether about it.
When a body is electrified, the latter at the same time creates an ether stress about it, which is called an electric field. The ether stress may be considered as a warp in the distribution of the energy about the body (Fig. 15), by the new positions given to the molecules by the process of electrification. It has been already said that the evidence from other sources is that atoms, rather than molecules, in larger masses, are what affect the ether. One is inclined to inquire for the evidence we have as to the constitution of matter or of atoms. There is [Pg 116] only one hypothesis to-day that has any degree of probability; that is, the vortex-ring theory, which describes an atom as being a vortex-ring of ether in the ether. It possesses a definite amount of energy in virtue of the motion which constitutes it, and this motion differentiates it from the surrounding ether, giving it dimensions, elasticity, momentum, and the possibility of translatory, rotary, vibratory motions, and combinations of them. Without going further into this, it is sufficient, for a mechanical conception, that one should have so much in mind, as it will vastly help in forming a mechanical conception of reactions between atoms and the ether. An exchange of energy between such an atom and the ether is not an exchange between different kinds of things, but between different conditions of the same thing. Next, it should be remembered that all the elements are magnetic in some degree. [Pg 117] This means that they are themselves magnets, and every magnet has a magnetic field unlimited in extent, which can almost be regarded as a part of itself. If a magnet of any size be moved, its field is moved with it, and if in any way the magnetism be increased or diminished, the field changes correspondingly.
Assume a straight bar electro-magnet in circuit, so that a current can be made intermittent, say, once a second. When the circuit is closed and the magnet is made, the field at once is formed and travels outwards at the rate of 186,000 miles per second. When the current stops, the field adjacent is destroyed. Another closure develops the field again, which, like the other, travels outwards; and so there may be formed a series of waves in the ether, each 186,000 miles long, with an electro-magnetic antecedent. If the circuit were closed ten times a second, the waves would be 18,600 miles long; if 186,000 times a second, they would be but one mile long. If 400 million of millions times a second, they would be but the forty-thousandth of an inch long, and would then affect the eye, and we should call them light-waves, but the latter would not differ from the first wave in any particular except in length. As it is proved that such electro-magnetic waves have all the characteristics of light, it follows that they must originate with electro-magnetic [Pg 118] action, that is, in the changing magnetism of a magnetic body. This makes it needful to assume that the atoms which originate waves are magnets, as they are experimentally found to be. But how can a magnet, not subject to a varying current, change its magnetic field? The strength or density of a magnetic field depends upon the form of the magnet. When the poles are near together, the field is densest; when the magnet is bent back to a straight bar, the field is rarest or weakest, and a change in the form of the magnet from a U-form to a straight bar would result in a change of the magnetic field within its greatest limits. A few turns of wire—as has been already said—wound about the poles of an ordinary U-magnet, and connected to an ordinary magnetic telephone, will enable one, listening to the latter, to hear the pitch of the former loudly reproduced when the magnet is struck like a tuning-fork, so as to vibrate. This shows that the field of the magnet changes at the same rate as the vibrations.
Assume that the magnet becomes smaller and smaller until it is of the dimensions of an atom, say for an approximation, the fifty-millionth of an inch. It would still have its field; it would still be elastic and capable of vibration, but at an enormously rapid rate; but its vibration would change its field in the same way, and so there would be formed [Pg 119] those waves in the ether, which, because they are so short that they can affect the eye, we call light. The mechanical conceptions are legitimate, because based upon experiments having ranges through nearly the whole gamut as waves in ether.
The idea implies that every atom has what may be loosely called an electro-magnetic grip upon the whole of the ether, and any change in the former brings some change in the latter.
Lastly, the phenomenon called induction may be mechanically conceived.
It is well known that a current in a conductor makes a magnet of the wire, and gives it an electro-magnetic field, so that other magnets in its neighbourhood are twisted in a way tending to set them at right angles to the wire. Also, if another wire be adjacent to the first, an electric current having an opposite direction is induced in it. Thus:
Consider a permanent magnet a (Fig. 15), free to turn on an axis in the direction of the arrow. If there be other free magnets, b and c, in line, they will assume such positions that their similar poles all point one way. Let a be twisted to a position at right angles, then b will turn, but in the opposite direction, and c in similar. That is, if a turn in the direction of the hands of a clock, b and c will turn in opposite directions. These are simply the [Pg 120] observed movements of large magnets. Imagine that these magnets be reduced to atomic dimensions, yet retaining their magnetic qualities, poles and fields. Would they not evidently move in the same way and for the same reason? If it be true, that a magnet field always so acts upon another as to tend by rotation to set the latter into a certain position, with reference to the stress in that field, then, wherever there is a changing magnetic field, there the atoms are being adjusted by it.
Suppose we have a line of magnetic needles free to turn, hundreds or thousands of them, but disarranged. Let a strong magnetic field be produced at one end of the line. The field would be strongest and best conducted along the magnet line, but every magnet in the line would be compelled to rotate, and if the first were kept rotating, the rotation [Pg 121] would be kept up along the whole line. This would be a mechanical illustration of how an electric current travels in a conductor. The rotations are of the atomic sort, and are at right angles to the direction of the conductor.
That which makes the magnets move is inductive magnetic ether stress, but the advancing motion represents mechanical energy of rotation, and it is this motion, with the resulting friction, which causes the heat in a conductor.
What is important to note is, that the action in the ether is not electric action, but more properly the result of electro-magnetic action. Whatever name be given to it, and however it comes about, there is no good reason for calling any kind of ether action electrical.
Electric action, like magnetic action, begins and ends in matter. It is subject to transformations into thermal and mechanical actions, also into ether stress—right-handed or left-handed—which, in turn, can similarly affect other matter, but with opposite polarities.
In his Modern Views of Electricity, Prof. O. J. Lodge warns us, quite rightly, that perhaps, after all, there is no such thing as electricity—that electrification and electric energy may be terms to be kept for convenience; but if electricity as a term be held to imply a force, a fluid, an imponderable, [Pg 122] or a thing which could be described by some one who knew enough, then it has no degree of probability, for spinning atomic magnets seem capable of developing all the electrical phenomena we meet. It must be thought of as a condition and not as an entity.
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