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Absolute magnitude (H10 and H0)
This is the brightness a comet would exhibit if placed 1 AU from both the Earth and sun. Using a special formula, the brightness estimates made for comets can be converted to absolute magnitudes which aids in the study of how a comet reacts as it approaches or recedes from the sun. For H0, an accompanying value designated “n” determines how fast a comet brightens or fades when approaching or receding from the sun.
The name given to a tail when it points towards the sun. This is a rare event and typically occurs when the Earth crosses the plane of the comet’s orbit when that comet is relatively close to the sun and exhibiting notable tail activity.
The point from which meteors appear to originate in the sky.
This is an angular measure frequently used to denote the size of a comet’s coma and tail. One arc minute is 1/60th of a degree.
This is an angular measure frequently used to denote the size of a comet’s nuclear condensation. One arc second is 1/60th of an arc minute.
Astronomical unit (AU)
This is a standard unit of measure to represent the distances of objects within our solar system from the sun. One AU is 149,597,870 kilometers.
A very bright meteor which fragments or explodes. Sounds of the explosion can be heard if the observe is close enough.
A diffuse, luminous cloud of dust and gas that develops around a comet’s nucleus as it nears the sun.
One of the important pieces of information an observer can determine when viewing comets. The size is usually given in arc minutes, although distant comets can display a coma that is measured in arc seconds and near-Earth comets can display a coma that is measured in degrees.
A meteor stream that is active and above the horizon at the same time as the sun. They can only be observed by radar and radio-echo techniques.
The celestial equivalent of latitude. The celestial equator is zero degrees, while the celestial north and south poles are 90 and -90 degrees, respectively.
Degree of Condensation (DC)
A term used to denote how the comet’s surface brightness is concentrated within the coma. A DC of 0 indicates the comet surface brightness is evenly distributed with no apparent concentrated. A DC of 9 indicates the comet essentially looks like a planet.
A meteor which is brighter than any planet or star, i.e. brighter than magnitude -4.
Geocentric distance (delta)
The distance of an object from Earth, usually given in astronomical units.
Heliocentric distance (r)
The distance of an object from the sun, usually given in astronomical units.
Comets moving in orbits having periods greater than 200 years.
Magnitude (m1 and m2 for comets)
One of the most important pieces of information gathered by amateur astronomers. This represents the estimated brightness of the comet when compared to stars around it. The term “m1” is used to represent the total or integrated brightness of the comet’s coma, while “m2” represents the brightness of the nucleus. Observers estimate “m1” by usually memorizing the comet’s appearance and then defocusing the surrounding stars to a size equivalent to the comet’s coma diameter. The memorized comet’s appearance is then compared to the defocused stars to determine the comet’s brightness. In meteor astronomy the magnitude of a meteor is compared to that of other stars in the sky. The magnitude scale is set up so that the brighter magnitudes are actually represented by smaller numbers. The sun is about magnitude -26, the moon -12, Venus is -4, and the faintest naked-eye star is generally about +6.
Popularly called a “shooting star” or a “falling star”, a meteor is actually an object usually ranging from the size of a dust particle to a rock that enters Earth’s atmosphere, and is heated by the friction of air resistence. Most meteors originate from comets.
A meteor that is large enough to survive its passage through the atmosphere and hit the ground.
A shower of meteors occurs when Earth’s orbit intersects the orbit of a meteor stream.
This is a rare event that occurs when Earth encounters closely grouped meteors within a meteor stream. Such events can see meteor rates exceeding 1000 per minute.
This represents the orbit of meteoroids as they travel around the sun. Meteors are the by-product of comets, so it is possible for the parent comet to be traveling in the same orbit–if it still exists.
A trail of ionized dust and gas that remains along the path of a meteor.
Minor Meteor Showers
Meteor showers that produce less than 10 meteors per hour at the time of maximum activity.
This is the photometric parameter generated when calculating a comet’s absolute magnitude. It indicates the comet’s rate of brightening and fading as it approaches or recedes from the sun, respectively.
The actual solid body of a comet. The nucleus is rarely visible when the comet is in the inner solar system because of the coma. It has been referred to as a “dirty snowball” because it is believed to be composed of about 75 percent of various ices and about 25 percent of various dusts. A photo of the nucleus of Halley’s comet by the Giotto probe revealed the nucleus as an asteroidal-looking body. Most comet’s have a nucleus that measures only a few kilometers across.
The amount of time, usually given in years, that it takes an object to orbit the sun.
Perihelion Date (T)
The date an object reaches its closest distance from the sun.
Perihelion Distance (q)
The point in an orbit when an object is closest to the sun. The value is usually given in astronomical units.
Train luminosity that lasts more than a second.
Position Angle (PA)
An angular measurement indicating which side of the nucleus something is located. A “PA” of 0 degrees indicates an object is located north of the nucleus, while 90 degrees indicates east, 180 degrees is south, and 270 degrees is west. It is most commonly used to indicate the direction the tail is pointing. On occasion, when a comet’s nucleus has broke up, the position angle is used to indicate which direction the nuclear fragments are located from the primary nucleus.
The point from which a meteor appears to emanate.
The movement of a meteor shower’s radiant against the star background. This characteristic is common to all meteor showers and is caused by Earth’s passage through a meteor stream.
The celestial equivalent of Earth’s longitude, beginning at a line running pole to pole and cutting through eastern Pegasus. In meteor astronomy the right ascension is handled in degrees, starting at zero degrees and advancing eastward around the sky for a full 360 degrees ending in eastern Pegasus. For the rest of astronomy, the right ascension is handled as a time measurement. Since it takes 24 hours for the Earth to rotate, the sky is divided into 24 one hour wide bands. Each hour of right ascension equals 15 degrees.
Comets moving in orbits having periods less than 200 years.
This is an angular measurement that specifies the location of Earth in its orbit around the sun. More precisely, it is the longitude of the sun as given in geocentric coordinates. The evaluation of meteor data strongly relies on this figure rather than a conventional date.
The most distinctive feature of comets, especially great ones. It is typically directed away from the sun. Ancient and medieval observers frequently described a comet as a broom or sword, depending on the look of the tail. Typically, telescopic comets will exhibit either no tail or one extending a few arc minutes. Naked-eye comets can show a tail extending up to several tens of degrees. Comets can display two basic types of tails: one gaseous and the other largely composed of dust. The dust tail can be curved, spread out, and yellowish in appearance, while the gas tail is usually very straight and bluish.
The flare at the end of a meteor’s path.
Zenithal Hourly Rate (ZHR)
This is the rate a meteor shower would produce if seen by an observer with a clear, dark sky, and with the radiant at the zenith. | 0.851033 | 4.027924 |
The ESA/JAXA BepiColombo mission completed its first flyby on 10 April, as the spacecraft came less than 12 700 km from Earth’s surface at 06:25 CEST, steering its trajectory towards the final destination, Mercury. Images gathered just before closest approach portray our planet shining through darkness, during one of humankind’s most challenging times in recent history.
Launched in 2018, BepiColombo is on a seven-year journey to the smallest and innermost planet orbiting the Sun, which holds important clues about the formation and evolution of the entire Solar System.
Today’s operation is the first of nine flybys which, together with the onboard solar propulsion system, will help the spacecraft reach its target orbit around Mercury. The next two flybys will take place at Venus and further six at Mercury itself
While the manoeuvre took advantage of Earth’s gravity to adjust the path of the spacecraft and did not require any active operations, such as firing thrusters, it included 34 critical minutes shortly after BepiColombo’s closest approach to our planet, when the spacecraft flew across the shadow of Earth.
“This eclipse phase was the most delicate part of the flyby, with the spacecraft passing through the shadow of our planet and not receiving any direct sunlight for the first time after launch,” said Elsa Montagnon, BepiColombo Spacecraft Operations Manager for ESA.
To prepare for the scheduled eclipse, mission operators fully charged the spacecraft batteries and warmed up all components in advance, then closely monitored the temperature of all onboard systems during the period in darkness, between 07:01 and 07:35 CEST.
“It is always nerve-wracking to know a spacecraft’s solar panels are not bathed in sunlight. When we saw the solar cells had restarted to generate electrical current, we knew BepiColombo was finally out of Earth’s shadow and ready to proceed on its interplanetary journey,” added Elsa.
Space operations are never routine at ESA’s mission control centre in Darmstadt, Germany, but today’s flyby had one extra challenge. The manoeuvre, programmed long in advance and impossible to postpone, had to be prepared with limited on-site personnel, amid the social distancing measures adopted by the Agency in response to the ongoing coronavirus pandemic; but the restrictions had no impact on the operation’s success.
As BepiColombo swung by our planet, most scientific instruments on ESA’s Mercury Planetary Orbiter – one of the two science spacecraft that make up the mission – were switched on. Several sensors were also active on the second component of the mission, JAXA’s Mercury Magnetospheric Orbiter, also known as Mio.
Scientists will use the data gathered during the flyby, which include images of the Moon and measurements of Earth’s magnetic field as the spacecraft zipped past, to calibrate the instruments that will, as of 2026, investigate Mercury to solve the mystery of how the scorched planet formed.
“Today was of course very different to what we could have imagined only a couple of months ago,” said Johannes Benkhoff, ESA’s BepiColombo Project Scientist, who followed the operation from his home in the Netherlands, along with the many scientists from the 16 instrument teams that comprise the mission, scattered between Europe and Japan.
“We are all pleased that the flyby went well and that we could operate several scientific instruments, and we are looking forward to receiving and analysing the data. These will also be useful to prepare for the next flyby, when BepiColombo will swing past Venus in October.”
“There is a great interest in Japan in the BepiColombo mission. Thus, after the successful flyby we are looking forward to the science at Venus and Mercury,” said Go Murakami, BepiColombo Project Scientist at JAXA.
Our home from space
On 9 April, ahead of the flyby, and then again today, just before closing in, the BepiColombo monitoring cameras snapped a series of images of Earth from space, picturing our planet in these difficult times for humans across Europe and the world.
“These selfies from space are humbling, showing our planet, the common home that we share, in one of the most troubling and uncertain periods many of us have gone through,” said Günther Hasinger, ESA’s Director of Science, who also followed the event remotely from home, in Spain.
“We are scientists who fly spacecraft to explore the Solar System and observe the Universe in search of our cosmic origins, but before that we are humans, caring for one another and coping with a planetary emergency together. When I look at these images, I am reminded of the strength and resilience of humankind, of the challenges we can overcome when we team up, and I wish they bring you the same sense of hope for our future.”
Join us on ESA Web TV on 10 April at 17:00 CEST for a live streamed conversation featuring ESA mission experts and scientists from some of the instrument teams, reflecting on the flyby and presenting data gathered by the different instruments: https://esawebtv.esa.int
For updates on the science data obtained during the flyby and images to be taken by the BepiColombo monitoring cameras as the spacecraft moves away from Earth on 10 and 11 April, follow the mission on Twitter via: @ESA_Bepi, @ESA_MTM, and @BepiColombo
BepiColombo is Europe's first mission to Mercury. Launched on 20 October 2018, it is on a seven-year journey to the smallest and least explored terrestrial planet in our Solar System. The mission is a joint endeavour between ESA and the Japan Aerospace Exploration Agency (JAXA), carried out under ESA leadership.
BepiColombo comprises two scientific orbiters: ESA’s Mercury Planetary Orbiter (MPO) and JAXA’s Mercury Magnetospheric Orbiter (Mio). After arrival at Mercury in late 2025, it will need more than 15 additional manoeuvres to place the two orbiters in their dedicated polar orbits around the planet. Starting science operations in early 2026, both orbiters will gather data during a one-year nominal mission, with a possible one-year extension. The mission is named after the Italian mathematician and engineer Giuseppe (Bepi) Colombo (1920–84).
Follow the mission via https://www.esa.int/BepiColombo/
The JAXA mission website is available in English here: http://mio.isas.jaxa.jp/en/
For further information
ESA Media Relations Office – Ninja Menning
Tel: +31 71 565 6409 | 0.870208 | 3.370909 |
In the 1890s Percival Lovell pointed the huge, 24-inch Alvan Clark telescope in Flagstaff, Arizona towards the planet Mars. Ever the romantic, he longed to find some sign of life on the Red Planet: To hold a mirror up to the empty sky above and find a planet that looked a little bit like home. Of course, in Lovell’s case, it was the telescope itself that gave the impression of life, imposing faint lines onto the image that he mistook for canals. But, with Mars long since relegated to the status of a dusty, hostile world, that ideal of finding such a planet still lingers. In the great loneliness of space, our species yearns to find a world like our own, maybe even a world that some other lineage of life might call home.
A hundred years after Lovell’s wayward romanticism, the real search for Earth-like planets began. A team of astronomers at the University of Geneva used precise spectroscopy to discover a Jupiter-sized world around the star 55-Peg. This was followed by a series of similar worlds; all distinctly alien with huge gas giants orbiting perishingly close to their stars. However, as techniques improved and more time & money was invested on exoplanet astronomy, that initial trickle of new worlds soon turned into a flood. By 2008 more than 300 planets had been discovered including many multi-planet systems and a handful of potentially rocky planets around low-mass stars. However, the ultimate goal of finding Earth-like planets still seemed an impossible dream.
In 2009 the phenomenally sensitive Kepler mission launched. Here was a mission that might finally discover Earth-sized planets around Sun-like stars, detecting the faint dip in light as they passed between their star and us. Four years, 3500 planetary candidates and 200 confirmed planets later, the mission was universally declared a success. Its remarkable achievements include a handful of new terrestrial worlds, such as Kepler-61b and 62e, orbiting safely within their star’s habitable zones. However, despite lots of column inches and speculation, are these planets really the Earth 2.0s we were sold?
Even more damning is the size of these planets. Rather than being truly Earth-like, the crop of currently known ‘Habitable planets’ are all super-Earths. In the case of Kepler’s goldilocks worlds, this means they have radii between 1.6 and 2.3 times that of Earth. That may not sound too bad, but the mass of each planet scales with the volume. That means, when compression due to gravity is taken into account, for such planets to be rocky they would need masses between 8 and 30 times that of Earth. With 10ME often used as the likely limit of terrestrial planets, can we really call such planets Earth-like. In fact, a recent study of super-Earths put the maximum theoretical radius for a rocky planet as between 1.5 and 1.8RE, with most worlds above this size likely being more like Mini-Neptunes.
So it appears our crop of habitable super-Earths may not be as life-friendly as previously thought. But it is true that deep in Kepler’s 3500 candidates a true Earth-like planet may lurk. However the majority of Kepler’s candidates orbit distant, dim stars. This means the hope of confirming these worlds by other techniques, especially tiny exo-Earths, is increasingly unlikely. And with Kepler’s primary mission now ended by a technical fault, an obvious question arises: just when and how will we find a true Earth analogue?
Future exoplanet missions may well be numerous, but are they cut out to discover a true Earth-like planet? The recently launched Gaia spacecraft, for example, will discover hundreds of Gas Giants orbiting Sun-like stars using the astrometry technique, but it would need to be around a hundred times more sensitive to discover Earths. New ground-based transit surveys such as NGTS are set to be an order of magnitude better than previous such surveys, but still these will only be able to find super-Earth or Neptune-sized worlds.
Similarly, Kepler’s successor, the Transiting Exoplanet Survey Satellite which is due to be launched in 2017, will only be able to find short-period planets with radii more than 50% larger than Earth. HARPS, the most prolific exoplanet-hunting instrument to date, is also due for an upgrade by 2017. Its protégée is a spectrometer named ESPRESSO that will be able to measure the change in velocity of a star down to a mere 10cms-1. Even this ridiculous level of accuracy is not sufficient to detect the 8cms-1 effect Earth’s mass has on the Sun.
While such worlds may well have surfaces with beautifully Earth-like temperatures, there are a number of problems with calling such worlds definitive Earth twins. For a start the majority of these potentially habitable planets (such as Kepler-62e) orbit low-mass M and late K-type stars. These are dimmer and redder than our Sun and, due to the relative distance of the habitable zone, such planets are likely to be tidally locked. The nature of such stars also makes them significantly more active, producing more atmosphere-stripping UV radiation. This means, despite appearances, ‘habitable’ planets around M-dwarfs are almost certainly less conducive to life than more sun-like stars.
So despite billions spent on the next generation of planet-finders, they all fall short of finding that elusive second Earth. What, precisely, will it take to find this particular Holy Grail? There is some hope that the E-ELT (European-Extremely Large Telescope), with its 35m of collecting area and world-beating instruments will be able to detect exo-earths. Not only will its radial velocity measurements likely be sensitive enough to find such planets, it may also be able to directly image earth-analogues around the nearest stars. However, with observing time likely to be at a premium, the long-duration observations required to find and study exo-earths could prove difficult.
Alternatively, large space telescopes could be the answer. JWST will be able to do innovative exoplanet research including taking direct images of long-period planets and accurate atmospheric spectra of transiting super-Earths and giants. Even more remarkably, it may manage to take spectra of habitable zone super-Earths such as GJ 581d. But direct detection of true Earth-analogues remains out of reach. An even more ambitious project may be required, such as TPF or Darwin. These were a pair of proposals that could have directly imaged nearby stars to discover Earth-like planets. However, with both projects long since shelved by their respective space agencies, the future doesn’t look so bright for Earth-hunting telescopes.
After the unabashed confidence of the Kepler era, the idea that no Earth-like planet discovery is on the horizon may come as a surprisingly pessimistic conclusion. However not all hope is lost. The pace of technological advancement is quickening. Instruments such as TESS, Espresso, E-ELT and JWST are already being built. These missions may not be perfectly designed to the technical challenge of discovering truly Earth-like planets, but they will get us closer than ever before. As a civilisation we have waited hundreds of years for such a discovery; I’m sure we can hold out for a few more. | 0.874147 | 3.77211 |
The deficiency of star formation in dwarf galaxies
Dwarf galaxies form stars very inefficiently compared to spiral galaxies like our Milky-Way. To investigate the origin of this deficiency in star formation, scientists at MPA have used high-resolution numerical simulations to resolve the evolution of the interstellar medium (ISM) in dwarf galaxies. They find that supernova explosions have a significant impact on the structure of the ISM and regulate the star formation rates of the whole galaxy. The reservoir for star formation on scales comparable to molecular clouds in our Milky Way consists mainly of cold atomic hydrogen rather than molecular hydrogen. These findings might also shed light into the birth processes of most other galaxies. Within the current paradigm of hierarchical structure formation, low mass, chemically un-evolved dwarf galaxies are the building blocks of all, more massive galaxies.
In typical spiral galaxies, observations have shown a correlation between the surface density of the local star formation rate and the gas surface density, the so-called Kennicutt-Schmidt relation. The correlation is almost linear, i.e. the gas is converted into stars on a constant timescale of ~2 billion years. In the Milky-Way and other spiral galaxies star formation appears to happen exclusively in regions dominated by molecular gas.
However, this linear correlation breaks down in dwarf galaxies, where stars form very inefficiently on timescales that are much longer: 10-100 billion years. It is not yet clear whether the star forming gas in these dwarf galaxies consists mainly of molecules or atoms. Observations have not yet detected molecular gas but it has been speculated that an unseen molecular reservoir could dictate the star formation rate. This would provide an explanation for the longer star formation timescales in dwarf galaxies, which could be regulated by an inefficient transition from the atomic to molecular state.
Recently, scientists at MPA have investigated the star formation in dwarf galaxies using numerical hydro-dynamical simulations, which incorporate a wealth of relevant physical processes. In particular it is assumed that molecular hydrogen forms on dust grains and that interstellar UV starlight can destroy the molecules. The simulations were conducted at an unprecedented high resolution (with a spatial resolution of 2 Parsec and matter particles of 4 solar masses). The impact of individual supernova explosions is numerically resolved. Fig. 1 shows a snapshot of the gas surface density in one of the simulations at different spatial scales, demonstrating the complexity of the multi-phase gas structure.
The simulations suggest that the star formation reservoir (the cold and dense gas) is predominately in the atomic phase, contrary to the situation in spiral galaxies. This is because it takes much longer for molecular hydrogen to form in a low-metallicity environment. As the ISM is constantly shaken and stirred by supernova explosions, the molecular hydrogen has no time to reach its (chemical) equilibrium abundance. The supernova explosions inject energy and momentum into the gas, triggering turbulence and shocks, much faster than the gas can cool or heat through radiative processes. As such, the gas is also driven out of thermal equilibrium (Fig. 2).
Comparing the Kennicutt-Schmidt relation of these simulations with observations of dwarf galaxies one finds good agreement (Fig. 3). The longer timescales compared to spiral galaxies (which is about 2 billion years) is caused by the inability of gas to cool in the outer part of the galaxy. As explained above, this prevents the ISM to form the cold gas needed for effective star formation.
The simulations also demonstrate that, while a change in the dust abundance or the interstellar UV radiation has a dramatic impact on the molecular abundance, it does not affect the thermal gas properties. This suggests that molecular hydrogen plays little role in regulating star formation in dwarf galaxies and is not a good tracer for it – in contrast to spiral galaxies like the Milky Way.
Chia-Yu Hu & Thorsten Naab
(Stefanie Walch, Simon Glover, Paul Clark)
This work is supported by: | 0.866318 | 4.158822 |
Oct 25, 2013
Data from the MESSENGER probe to Mercury continues to provide evidence for the Electric Universe theory.
The planet Mercury has no atmosphere and little in the way of a magnetic field, so it is bombarded by the full force of the Sun’s radiation. Since the Moon is also an airless world, with only traces of a magnetic field, perhaps explanations applicable to the Moon or Mars might help to explain Mercury’s features.
The Moon is 3472 kilometers in diameter and Mercury is 4878 kilometers in diameter, their surfaces are almost identical in appearance. The lack of atmosphere and low gravity contribute to a lack of erosion on both bodies, but the various formations on both reveal a high level of congruency. The surfaces of the Moon and Mercury are also composed primarily of basalt, the most common mineral in the Solar System.
According to MESSENGER team members, an “unexpected class of landform on Mercury” has been found, suggesting a “previously unrecognized geological process is responsible for its formation.” It is not surprising that the processes that create the topography in question remain puzzling to planetary scientists: the features are reminiscent of formations on the Moon, particularly the Ina Structure. Mars might also figure into the discussion when the hollowed out mounds on the flanks of Olympus Mons are considered.
“Small, shallow, irregularly shaped depressions that are often found in clusters,” could be a defining characteristic of electric spark machining on a conductive surface, rather than the remains of volcanic vents, or places where trapped subsurface gases have erupted under pressure. One key to their understanding might lie in the brightness of the ridges within the “hollows.”
On Venus, the bright tops of mountains were theorized to be due to something like St. Elmo’s fire playing across the peaks. Since plasma is highly reflective of radar light, and the surface of Venus was mapped using radar to penetrate the clouds, the conjecture seems logical considering Electric Universe ideas. Since MESSENGER is using a multi-spectral high resolution imaging system, the bright ridges are most likely due to chemical changes from intense plasma discharges.
When basalt is baked, it releases gases that cause it to turn from a dark color to a light color. It might be that electric arcs excavated the depressions with white hot ion beams, hardening and lightening the surface. Similar processes could also be responsible for the comparative formations on the Moon and Mars.
Mercury is believed to be almost 75% iron surrounded by a thin shell of silicon-rich rock. Conventional theories of planet formation have no explanation for such a configuration. If it formed in the same protoplanetary nebula as the rest of the Solar System, then the abundance of iron remains a mystery because the ratio of iron to silicon is opposite to the other rocky planets. Mercury is thought to have a molten core generating a magnetic field, but no one knows if it is working like Earth’s is supposed to work or if the field is part of the crust, like Mars. No one understands how a molten core exists on Mercury since the planet appears cold and dead. The molten interior should have cooled off eons ago.
As Electric Universe proponent Wal Thornhill wrote: “In Mercury’s case, its strong gravitational field for its size indicates a high level of internal electrical polarization. That means a high surface charge. So Mercury’s slowly rotating charge will produce a small magnetic field. Other effects will modify that field. For example, currents flow in the plasma above the surface and are induced in the surface of the planet. And there is remanent magnetism associated with old cosmic thunderbolt surface scars.”
Click here for a Spanish translation | 0.870139 | 4.04609 |
In this post I’ll talk about Nicolas Copernicus (1473 – 1543) and the heliocentric theory. The move away from the prevailing Earth-centred theory of the Universe to the heliocentric theory represents one of the greatest advances in astronomy ever made.
Nicolas Copernicus – Image from Wikimedia Commons
Background – the need for a better theory
As mentioned in my last post, the geocentric theory was the generally accepted theory of the cosmos until the early 16th century, having been developed by the second century Greek astronomer Claudius Ptolemy. To make it fit the observations, Ptolemy needed to fine-tune his theory, making it rather complex. Rather than moving directly around the Earth, the Sun, the Moon and the planets moved around small circles called epicycles and the centre of each epicycle moved, at a varying speed, around a larger circle called a deferent. A further complexity was that the centre of the deferent wasn’t the Earth but a point nearby, which Ptolemy called the ‘eccentric’. This was at a different location for each planet. This is shown in the diagram below (to simplify the diagram only a single planet, Mars, is shown).
Ptolemy’s model – (Note the equant is another theoretical point described in my previous post.)
By the year 1500 observations had shown that the predictions of Ptolemy’s theory still didn’t quite match the actual positions of the planets. Because the geocentric model was generally accepted, the way astronomers made it fit the observations was to add additional epicycles, as shown in the diagram below.
In the revised geocentric model:
- each planet revolved around a small epicycle – shown in green
- the small epicycle revolved around a main epicycle – the blue dashed line
- the main epicycle revolved at an uneven speed around the deferent
- the deferent was centred at a point near the Earth called ‘the eccentric’.
This made the theory rather unwieldy and it appeared somewhat cobbled together. In fact the term ‘adding epicycles’ is used today in a derogatory way to mean making a bad theory over-complicated in order for it to fit the facts.
In 1473 Nicolas Copernicus was born, in the city of Torun in northern Poland into an influential and wealthy family. His father died when was 10 and the education of Nicolas, a bright child, was supervised by his uncle Lucas Watzenrode the Younger. His uncle was a influential prince-bishop (a bishop who was also a secular ruler over a region of Poland), in contact with many of the leading intellectual figures in the country.
After he left school, Copernicus went to the University of Krakrow from 1491 to 1495 where he studied mathematics and astronomy, under some of the leading intellectuals in Poland. Although he did not graduate, his studies at Krakow gave him the grounding for his later work. Mrs Geek and I were lucky enough to see the rooms occupied by Copernicus’s tutors during our recent visit to Poland.
Part of a dining room at the Jagiellonian University in Krakow, Poland, where Copernicus studied. Founded in 1364, it is one of the oldest universities in the world. This photo was taken by Mrs Geek during our recent visit to Krakow.
After leaving Krakow, Copernicus studied ecclesiastical law and medicine in Italy before moving back to Poland in 1503 to live in the town of Warmia, which was governed by his uncle, and he lived there for most of the rest of his life. Rather than being a professional scientist, his main job was as a Catholic clergyman and local government official.
In around 1510 Copernicus started work on the heliocentric theory of the Universe. His aim was to provide a more accurate and a simpler explanation of the cosmos. The main points of Copernicus’s theory were as follows:
- The Sun (not the Earth) was the centre of the Universe. The Earth and all the planets moved in perfect circles around it.
- The Moon was the only astronomical object which orbited the Earth.
- The Sun is much nearer to the Earth than any of the other stars, by a vast measure.
- The daily rising and setting of the Sun, Moon, planets and stars are explained by the rotation of the Earth on its axis.
The third point was needed because if some stars were relatively close to the Sun, for example only 100 times the distance between the Earth and the Sun, then there would be a measurable ‘stellar parallax’ effect, where the nearby stars would appear to be in a different position at different times of year.
Stellar Parallax – at different times of year, the nearby star appears to be in different positions with respect to the background of fixed stars.
Because stellar parallax had never been observed, Copernicus concluded that all the stars must be at a vast distance from the Sun. The parallax is so small that it couldn’t be measured in Copernicus’s time. It wasn’t detected until the mid nineteenth century.
Mercury and Venus
Mercury and Venus differ from the other planets in that, to an observer on the Earth, they never stray too far away from the Sun and, to viewers at low latitudes, they can only be seen for a few hours after sunset or a few hours before sunrise. The reason why Venus and Mercury always appear in the same part of the sky as the Sun is neatly explained by Copernicus’s theory in that their orbits lie inside the Earth’s orbit.
Venus cannot appear more than 46 degrees away from the Sun. The green line shows the limits of Venus’s apparent position from the Sun.
Copernicus refined his theory over the next 20 years to match accurate observations that he and other astronomers had taken. As he did so, his ideas began to circulate among the educated elite within Europe. He had finalised his theory by 1530, but he was extremely reluctant to publish it. He was well aware that it would cause a massive controversy, for at the time the Ptolemaic system was generally accepted by virtually all astronomers. With his ecclesiastical background, Copernicus also knew there would be religious objections, for certain verses in the bible could be interpreted as saying that Earth was stationary and rest of the Universe was in motion around it.
Under pressure from colleagues to make his ideas more widely known, in 1543 he finally agreed to publish them in a book called ‘De revolutionibus orbium coelestium‘ (On the Revolutions of the Heavenly Spheres). By this time Copernicus was ill and near the end of his life. His book, like most scientific literature of time, was written in Latin and, perhaps to ward off the religious objections he knew would arise, he dedicated the book to the pope. The printing of the book was supervised by the German theologian Andreas Osiander, as Copernicus was too ill to do it himself. Unbeknown to Copernicus, Osiander added a preface saying that the heliocentric theory should only be considered as another model of the Universe, which could be used to predict the positions of the stars and planets, and should not be taken as true, the truth being known only to God.
Although the book escaped initial censure, over the 50 years following its publication the Catholic church became more and more hostile to heliocentrism and eventually regarded anyone holding these views as a heretic. The Italian astronomer and philosopher Giodarno Bruno was burned at the stake in 1600; one of the main charges against him was promoting a heliocentric view of the Universe.
In 1616 De revolutionibus was placed on the list of banned books by the Catholic church, where it would remain for the next 200 years.
The Protestant churches too were extremely critical of Copernicus’s ideas. About ten years before the publication of of De revolutionibus, when Corpernicus’s ideas were becoming known, the German theologian Martin Luther said:
‘There is talk of a new astrologer who wants to prove that the Earth moves and goes around instead of the sky, the Sun, the Moon, just as if somebody were moving in a carriage or ship might hold that he was sitting still and at rest while the Earth and the trees walked and moved. But that is how things are nowadays: when a man wishes to be clever he must needs invent something special, and the way he does it must needs be the best! The fool wants to turn the whole art of astronomy upside-down. However, as Holy Scripture tells us, so did Joshua bid the sun to stand still and not the Earth’ (Pogge 2005).
Refining the heliocentric theory.
Like all earlier astronomers, Copernicus still believed, probably for philosophical reasons, that the planets must move in perfect circles. So in order to make his theory fit the facts he needed to retain the concept of epicycles. The heliocentric theory was refined in the early seventeenth century by Johannes Kepler (1571-1630), who formulated a set of rules which became known as Kepler’s laws of planetary motion. These state that the planets move in elliptical orbits around the Sun and that they move at varying speeds around these orbits, moving faster when they are closer to the Sun. In this theory, Kepler removed the need for epicycles altogether and produced a simpler model which accurately fitted the observations. Kepler’s theory, which in turn led to Issac Newton developing his theory of gravity, is such a large topic that I will discuss it in more detail in a future post.
Legacy of Copernicus
Copernicus removed the Earth from the centre of the Universe and his theory provided the foundation for the later work of Kepler. In cosmology, there is an important concept called the ‘Copernican principle’. It states that the Earth, the Solar System and even the Milky Way galaxy are not in a special place in the universe. We belong to an average planet, orbiting an average star, on the edge of an average galaxy.
Copernicus’s contribution to science has been acknowledged in many ways. He is one of the few people to have an element in the period table named after him, copernicium, element 112. There are numerous statues and monuments to him including this one below in the Jagiellonian University in Krakow.
Photo taken by Mrs Geek
In Torun, Copernicus’s birthplace, the Nicolaus Copernicus University has over forty thousand students and is one of the largest universities in Poland, and the airport in Poland’s fourth largest city Wrocław is named after him.
Pogge, R (2005) A brief note on religious objections to Copernicus, Available at:http://www.astronomy.ohio-state.edu/~pogge/Ast161/Unit3/response.html (Accessed: 20 November 2017). | 0.901764 | 3.650485 |
The physicist advocates for the use of small, experimental spacecraft.
Professor Robyn Millan thinks small—small satellites, that is. On Jan. 31, she went to Washington, D.C., where she extolled the virtues of diminutive spacecraft.
At the invitation of the National Academy of Sciences, Millan, the Margaret Anne and Edward Leede ’49 Distinguished Professor of Physics and Astronomy, spoke to a group of about 50 scientists and engineers, some of whom had been involved in the early days of the space race, back in the 60s. It was 60 years to the day since the United States launched its first satellite, Explorer 1, just 14 months after the Soviets’ Sputnik 1 reached orbit. “Something like 69,000 people also watched the videocast, which I am glad I didn’t know beforehand,” she says.
Millan talked about the legacy and the future of small satellites, how the payloads started small—as Sputnik and Explorer were—and grew large over time. And how, with their increasing size, they took longer to develop and became expensive, heavier, and harder to launch. Now there has been a resurgence—an exponential growth—in the use of small spacecraft.
“There has been a lot of interest in the space research community because the hope is that by building these small things we can start to do different kinds of science. Launching an array of small satellites can permit multiple measurements in real time, like a series of buoys in the ocean or weather stations on Earth,” says Millan.
She says they are cost-effective, allowing their use in places too risky for a larger, more expensive satellite. “Building a small satellite may cost $1 million, while a larger one can require hundreds of millions. You could do things like let them dive deep into the atmosphere and let them burn up, but you’re learning something on the way in, and you don’t lose your billion-dollar mission.”
Small satellites are well suited for Millan’s area of study—the potentially destructive, high-energy electrons that streak into Earth’s atmosphere from the sun at velocities approaching the speed of light. They may cause ozone depletion and can damage the orbiting satellites that are used for navigation and communication. She had previously used a series of high-altitude balloons carrying X-ray detectors, but satellites can stay in positions for months or even years, collecting significantly more information.
Millan’s space physics research has applications that go beyond Earth’s orbit. “There is going to be a little more of a shift toward human exploration which we had seen with previous administrations,” she says, “and in order to send people to Mars and the moon, you need to understand the radiation environment to which people and their equipment will be exposed. The science that we are doing is directed toward an understanding of the environment that people will need to survive in—a changing environment that depends on the activity of the sun.”
Millan’s proposal for a CubeSat experiment was recently selected for funding by NASA. The CubeSat-based research will build on the results of the balloon program. “It is a follow-on to try and understand some of things we found in the balloon experiment regarding the rain of particles falling to Earth.”
As the name implies, a CubeSat is a cube-shaped device, designed to operate as a miniature satellite. It is about four inches on a side and several can be strung together to carry a variety of monitoring and measuring instruments.
Millan plans to involve her students in the construction and development of the new CubeSat, much as she did in the balloon experiments. “Right now, space is booming again, attracting private companies like SpaceX and Virgin Galactic,” she says. “I am even seeing it in the undergraduates, with a lot more students interested in space again, and getting excited about it.”
She says she is “always recruiting students. We can involve undergraduates in pretty much all aspects of the research. It’s just a matter of finding the right project and mentoring them.”
Her current undergraduate cadre includes Andrew Sosanya ’20, who is working on a data analysis project from the balloon experiment. “Working in the lab has given me an insight into space physics research—research that is experimental and much more hands-on than theoretical research,” he says.
Claire Gasque ’19 has worked with Millan for more than a year on a project using NOAA satellite data to investigate high-energy particles in the upper atmosphere. “One of my favorite experiences working with Professor Millan involved machine learning techniques,” says Gasque. “Neither of us had any prior knowledge of the topic, so, last fall we took an online machine learning course together, meeting weekly to discuss how the course topics could relate to my project. I loved the whole experience, not just learning from, but learning with a professor.”
Among her former students, Millan mentions two who have pursued careers in the space industry. “Julianna Scheiman ’11 graduated with an engineering degree and is now a manager on the SpaceX landing booster program. She worked on the balloon project when we were just getting started and told me the reason she got her job was the hands-on experience she got working with us.” Another alumna, Kathryn Waychoff ’16, works for Blue Origin, an aerospace manufacturer and spaceflight services company set up by Amazon founder Jeff Bezos. Millan says Waychoff is involved in designing a lunar lander.
“Promoting student involvement is important because it helps people understand that what we are doing on the research side of things is actually benefiting the students a lot,” says Millan. “I encourage students to get into research early in their time at Dartmouth and try a few different things. I’d like all of our students to have many opportunities to figure out what they really love to do.”
Joseph Blumberg can be reached at [email protected]. | 0.815825 | 3.350511 |
Four trips to the Moon a day? That’s one capability of a theoretical vehicle discussed in last January’s newsletter from the American Institute of Aeronautics and Astronautics. I hadn’t realized the AIAA was putting these newsletters online until I saw Adam Crowl’s post on Crowlspace discussing the above possibility. Adam notes that a vehicle powered by a so-called Mach-Lorentz Thruster (MLT) of the sort being studied by James Woodward (California State University, Fullerton) could not only make the four lunar trips a day but deliver almost 3000 tons of cargo a year.
The AIAA story, adapted by Paul March from his later presentation at the 2007 STAIF meeting (Space Technology and Applications International Forum) in Albuquerque, presents several startling scenarios, all of which come down to our understanding of inertia. Go back to the days of Isaac Newton and inertia is seen as an inherent property that causes a body to resist acceleration. Inertia means a body at rest will oppose anything that tries to get it into motion. And if it is already moving, inertia is that property that resists attempts to change the magnitude or direction of its velocity. [Addendum: Slightly changed from the original; see Jimmy Cone’s comment below].
But what causes inertia? Woodward, a professor of history as well as physics at Fullerton, sees inertia as the result of all objects in the universe — even the most distant — acting on an accelerated object. The concept is based on Mach’s Principle (named for 19th Century Austrian physicist Ernst Mach), and it may remind you a bit of some of our discussions about John Cramer’s Transactional Interpretation of quantum mechanics. Perhaps pushing on an object causes a gravitational disturbance that moves into the future, ultimately causing all other matter to move infinitesimally, creating a disturbance that moves backward in time and converges on the original object.
And thus you have one explanation for inertia. To say this is controversial is to belabor the obvious — among the scientists who abandoned Mach’s view was Einstein. But Woodward goes on, using Mach’s ideas, to show that objects undergoing acceleration experience transient fluctuations in their mass. Can these variations help us create spacecraft that expel no propellant? Woodward has been working on the concept since 1990, and the AIAA article offers a good introduction to his investigations. Here Paul March discusses the mass fluctuations under discussion:
The M-E [Mach Effect] is based on the idea that when a mass is accelerated through a local potential field gradient, its local rest mass is momentarily perturbed about its at-rest value. These resulting acceleration induced “mass fluctuations” used in conjunction with a secondary force rectification signal can then be used to generate an unbalanced force in a local mass system, which can accelerate a payload or generate energy. Local system energy and momentum conservation is maintained by interactions with all the distant mass in the universe. Therefore to accelerate a spacecraft here, the Machian interpretation of inertial reaction forces means that each star or other distant matter in the universe will move in the opposite direction of the locally accelerated mass in response here – even if only on an extremely small scale. Conservation of energy and momentum must be maintained globally, but nature doesn’t say how big the system box has to be, nor when the accounting has to be done.
Woodward’s continuing experiments at the ‘tabletop’ level have been provocative, and John Cramer investigated mass fluctuation under the auspices of the Breakthrough Propulsion Physics program in the late 1990s, although, as March notes, with inconclusive results. March goes on to the crux of things in describing a thruster built on these principles:
Assuming that mass fluctuations really do exist, in theory an M-E thruster can be built using externally applied forces that can push on the device’s “active” mass when it is lighter and then pull on this active mass when it is heaver in a cyclic manner, thus generating a net time-averaged force per Newton’s F=ma relationship.
Build a true Mach-Lorentz Thruster — assuming such a thing is possible — and if the technology scales the way Woodward believes it must, the outer Solar System is reachable in less than a month. In fact, the travel times are limited largely by the accelerations a human crew could endure. Clearly, the implications for interstellar missions are interesting indeed. But we’re a long way from building such devices. Indeed, conclusively verifying the viability of the thruster principle is still a work in progress, much less building larger MLTs to examine scaling issues.
Woodward’s ideas continue to be investigated. Peter Vandeventer has collected a number of non-published papers on his Woodward Effect site, while Woodward’s own home page offers useful background studies. Given the scope of the challenge of reaching the outer planets with human crews — much less the closest stars — it’s clear that major breakthroughs have to occur to replace conventional rockets and their bulky propellants. We’ll know one day if Woodward’s contribution to breakthrough propulsion physics can provide the answer. Right now we’re still trying to see if MLTs and the the Mach Effect itself make sense. | 0.885988 | 3.71093 |
ABOUT THIS IMAGE:
This sequence of images taken by NASA's Hubble Space Telescope shows Comet 252P/LINEAR as it passed by Earth. The visit was one of the closest encounters between a comet and our planet.
The images were taken on April 4, 2016, roughly two weeks after the icy visitor made its closest approach to Earth on March 21. The comet traveled within 3.3 million miles of Earth, or about 14 times the distance between our planet and the moon. These observations also represent the closest celestial object Hubble has observed, other than the moon.
The images reveal a narrow, well-defined jet of dust ejected by the comet's icy, fragile nucleus. The nucleus is too small for Hubble to resolve. Astronomers estimate that it is less than one mile across. A comet produces jets of material as it travels close to the sun in its orbit. Sunlight warms ices in a comet's nucleus, resulting in large amounts of dust and gas being ejected, sometimes in the form of jets. The jet in the Hubble images is illuminated by sunlight.
The jet also appears to change direction in the images, which is evidence that the comet's nucleus is spinning. The spinning nucleus makes the jet appear to rotate like the water jet from a rotating lawn sprinkler. The images underscore the dynamics and volatility of a comet's fragile nucleus.
Comet 252P/LINEAR is traveling away from Earth and the sun; its orbit will bring it back to the inner solar system in 2021, but not anywhere close to Earth.
These visible-light images were taken with Hubble's Wide Field Camera 3. | 0.874038 | 3.504018 |
Chemical traces from star formation cast light on cosmic history
Fresh insight into how stars are formed is challenging scientists’ understanding of the Universe.
A study of intense starbursts – events in distant galaxies in which stars are generated hundreds or thousands of times faster than in our Milky Way – is changing researchers’ ideas about cosmic history.
The findings will help scientists understand how galaxies in the early Universe evolve into those we see today.
Instead of observing the optical light from starbursts, which is obscured by enormous quantities of dust, scientists instead observed radio waves, measuring the relative abundances of different types of carbon monoxide gas.
They were able to differentiate between the gas expelled from massive stars, which shine very brilliantly for a short time, and that expelled from less massive stars, like our own Sun, which can shine steadily for billions of years.
Applying this novel technique for the first time, astronomers found that stars born inside galaxies undergoing a powerful starburst tend to be massive. In this regard, these are very different from those born inside galaxies that build up their stars over billions of years.
Scientists verified their findings using powerful computer models based on the evolution of our Milky Way galaxy and by observing starburst galaxies in the early Universe, which formed within a few billion years of the Big Bang. Such young galaxies are unlikely to have undergone previous episodes of star formation, which might otherwise have confused the results.
Researchers collected their data using the powerful ALMA telescope in the high Atacama Desert in Chile.
The five-year study, published in Nature, was carried out by astronomers at the University of Edinburgh and the European Southern Observatory (ESO), working alongside experts in Italy and Greece. It was supported by the European Research Council.
The ALMA telescope is operated by a partnership of the ESO, the US National Science Foundation and the National Institutes of Natural Sciences of Japan, in cooperation with the Republic of Chile.
Dr Zhi-Yu Zhang, of the University of Edinburgh’s School of Physics and Astronomy, who led the study, said: “Traditional telescopes are of limited use when studying dusty starburst galaxies. We reached our results using a powerful new radio telescope, hunting for traces of chemical elements from past events. For astronomers, these are like fossils. The results challenge classical ideas about the formation of stars in galaxies across cosmic time.”
Professor Rob Ivison, of the University of Edinburgh’s School of Physics and Astronomy and ESO, said: “Our findings lead us to question our understanding of cosmic history. Astronomers building models of the Universe must now go back to the drawing board, with yet more sophistication required.” | 0.872324 | 4.080517 |
From liquid-filled canyons on Io to super-sized meteor showers, this year has been full of fascinating news about our solar system. Now, a new discovery has scientists scratching their heads in wonder about what might lie at the edge of our cosmic neighborhood. A mysterious object was detected just past Neptune, and astronomers are unsure what gave it its unique properties.
An international team of astronomers researching the object has published the results of their study, which are still awaiting peer review. The newfound trans-Neptunian object is presumed to be a dwarf planet, and scientists have named it Niku. Based on its brightness, Niku is thought to be less than 200km in diameter. Several other dwarf planets and planetoids have been found recently near or beyond Neptune, and Niku was assumed to be similar to them. However, astronomers got a real treat when they began to observe and study Niku’s behaviors.
The mystery surrounding Niku stems from its strange orbit. While most objects orbit the Sun in the same direction as the Sun rotates, Niku orbits in the opposite direction. Furthermore, Niku orbits the Sun on a plane that is tilted 110 degrees off of the plane upon which the rest of the planets orbit. While other objects have been found that orbit the Sun in the opposite direction, the combination of these two facts is curious, to say the least.
As of now, scientists are unsure what to make of Niku’s unique orbit or how to explain it. Michele Bannister, an astronomer at Queens University Belfast, told New Scientist that the mystery of Niku makes it a prime subject for future study:
It’s wonderful that it’s so confusing. I’m looking forward to seeing what the theoretical analysts do once they get their hands on this one.
When solar systems form, the angular momentum, or spin, of forming stars create gas clouds spinning outwards from their centers; all the planets in our solar system orbit in the same direction due to the spin of our Sun as it formed. The unusual orientation and direction of Niku’s orbit thus imply that some cosmic event or object set it on its unusual course at some point in the past. What this might have been remains a mystery. | 0.867633 | 3.633743 |
Novae are kind of a big deal in the Universe, so you’d think that when one occurred we would notice, especially if it were visible to the naked eye. A star that exploded in June of 2007 in the constellation of Puppis, though, slipped by the network of professional and amateur astronomers that are dedicated to watching the skies for novel stars. Luckily, the orbiting X-ray telescope XMM-Newton just happened to be observing the area, and discovered the nova that everyone else had missed.
The satellite XMM-Newton is creating a survey of X-ray sources in the Universe, and on October 9, 2007 while turning from one target to another, it passed over a bright source of X-rays that was unexpected. The science team checked over their catalog of previously known X-ray sources in the area, but the only object with that location was the faint star USNO-A2.0 0450-03360039.
Andy Read of the University of Leicester and Richard Saxton of ESA’s European Space Astronomy Centre (ESAC), Spain quickly alerted other astronomers of the finding via the internet. Astronomers at the Magellan-Clay telescope at Las Campanas Observatory in Chile used their 6.5 meter telescope to analyze the light coming from the star and found that it had brightened by more than a factor of 600.
Saxton contacted the All-Sky Automated Survey, an automated survey of millions of stars, and found that the star went nova on June 5th, 2007. The nova has been given the shorter name of V598 Puppis, and had anyone been looking closely – even with the naked eye – at the constellation of Puppis on June 5th of 2007, they would have noticed the star brighten.
The image here shows V598 Puppis in the visible spectrum on the left, and in the X-ray on the right.
Novae of this type occur when a white dwarf, which is a smaller and more compact star, consumes material from a companion star, puffing it up. The nuclear processes in the star begin a runaway reaction after a certain amount of material is consumed, and it explodes violently.
What is curious about the case of V598 Puppis is that X-rays are only released from a nova after visible light. The expanding cloud of dust and debris from the initial explosion blocks most of the X-rays from being released. In the case of most other novae and supernovae, the discovery is made by a visible light telescope, then followed up by telescopes in the other spectra.
Source: ESA Press Release | 0.853215 | 3.949317 |
We think Earth’s volcanoes are pretty awesome, but the ones on Mars truly blow ours away.
There’s Tharsis, which once erupted so powerfully that it caused the entire planet to tilt on its axis. There’s Elysium, which has an exceptional chemical composition that’s baffled scientists. And then there’s Arsia Mons, a volcano lying just below Mars’s equator which actually has something in common with Earth, as scientists have just discovered.
New NASA research identifies the approximate timing of Arsia Mons’s extinction. According to a breaking report, the volcano used to erupt every 1 to 3 million years. Then, about 50 million years ago, it stopped producing lava altogether.
Enter another significant extinction in our solar system: that’s right, the obliteration of the dinosaurs (from an asteroid impact that, by the way, caused its own enormous volcanic eruption). NASA scientists now know that the deaths of the dinosaurs and Arsia Mons actually happened around the same time.
How’s that for interplanetary solidarity?
According to NASA’s report, Arsia Mons’ era of peak activity was probably around 150 million years ago, during Earth’s late Jurassic period. Its caldera — the crater formed when a volcano collapses into itself — is around 68 miles long and has 29 vents, out of which flowed .25 to 2 cubic miles of lava every million years, which is slow compared to volcanoes on Earth. Arsia Mons gradually grew out of these fluid lava flows, which makes it a “shield volcano” (because it’s low to the ground and therefore looks like a warrior’s shield … or at least, that’s the idea).
There’s still a lot we don’t know about Arsia Mons. In the report, NASA even acknowledged that there’s still a chance the volcano actually has gone off a couple of times within the last 50 million years, which would be quite recent, geologically-speaking. More research is essential, since volcanoes are one of the keys to understanding Mars’s history and development.
Presumably Arsia Mons saw the destruction on Earth and decided it’d be better to close up shop too. It must’ve been pretty depressing to witness the annihilation of a beast as awesome as the T-Rex (though we’re definitely better off without those guys). | 0.833939 | 3.033846 |
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A little interesting about space life.
Galilean Moons Of Jupiter. One dark, clear January night in 1610, Galileo Galilei climbed to the roof of his house in Padua. He looked up at the sky that was speckled with the flickering fires of a multitude of starry objects, and then aimed his small, primitive "spyglass"--which was really one of the first telescopes--up at that star-blasted sky above his home. Over the course of several such starlit, clear winter nights, Galileo discovered the four large Galilean moons that circle around the largest planet in our Sun's family, the enormous, gaseous world, Jupiter. This intriguing quartet of moons--Io, Europa, Ganymede, and Callisto--were named for four of the numerous mythic lovers of the King of the Roman gods.
and here is another
However, it was little Enceladus that gave astronomers their greatest shock. Even though the existence of Enceladus has been known since it was discovered by William Herschel in 1789, its enchantingly weird character was not fully appreciated until this century. Indeed, until the Voyagers flew past it, little was known about the moon. However, Enceladus has always been considered one of the more interesting members of Saturn's abundantly moonstruck family, for a number of very good reasons. First of all, it is amazingly bright. The quantity of sunlight that an object in our Solar System reflects back is termed its albedo, and this is calculated primarily by the color of the object's ground coating. The albedo of the dazzling Enceladus is almost a mirror-like 100%. Basically, this means that the surface of the little moon is richly covered with ice crystals--and that these crystals are regularly and frequently replenished. When the Voyagers flew over Enceladus in the 1980s, they found that the object was indeed abundantly coated with glittering ice. It was also being constantly, frequently repaved. Immense basins and valleys were filled with pristine white, fresh snow. Craters were cut in half--one side of the crater remaining a visible cavity pockmarking the moon's surface, and the other side completely buried in the bright, white snow. Remarkably, Enceladus circles Saturn within its so-called E ring, which is the widest of the planet's numerous rings. Just behind the moon is a readily-observed bulge within that ring, that astronomers determined was the result of the sparkling emission emanating from icy volcanoes (cryovolcanoes) that follow Enceladus wherever it wanders around its parent planet. The cryovolanoes studding Enceladus are responsible for the frequent repaving of its surface. In 2008, Cassini confirmed that the cryovolanic stream was composed of ordinary water, laced with carbon dioxide, potassium salts, carbon monoxide, and a plethora of other organic materials. Tidal squeezing, caused by Saturn and the nearby sister moons Dione and Tethys, keep the interior of Enceladus pleasantly warm, and its water in a liquid state--thus allowing the cryovolcanoes to keep spewing out their watery eruptions. The most enticing mystery, of course, is determining exactly how much water Enceladus holds. Is there merely a lake-sized body of water, or a sea, or a global ocean? The more water there is, the more it will circulate and churn--and the more Enceladus quivers and shakes, the more likely it is that it can brew up a bit of life.
Other authors make similar assertions. In Our Mysterious Spaceship Moon (Dell, 1975), author Don Wilson publishes the following conversation between the Eagle crew and Mission Control, presumably picked up by ham radio operators during a broadcast interruption attributed by NASA to an "overheated camera":
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- Vostok Rocket Bottom
- NASA Apollo Capsule
- Is Apollo 18 Really Real
- Properties of Galaxies HD
- NASA Leaving Earth
- Space Race NASA Companies
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- Paragraph On Solar System
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- Interstellar Spacecraft Details Movie
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Now, the fishing magazines and sites around the Internet will have you believe that the relationship between solar/lunar cycles and fishing is much more complex than I have explained here. In reality it's not. In fact, if you try to follow most of the charts out there, you will find no direct correlation between those charts and the number and size of fish you catch.
The night sky is a bottomless pit of darkness sprinkled generously with twinkling stars and during the new moon phase, which will take place on 16th June 2015, their will be no moon visible. This is the perfect time to dust off your telescope and indulge in an opportunity to properly study the stars without the interference of moonlight dampening your space 'exploration'. If you do not have a telescope then check out some telescope reviews and find a worthy telescope for sale... You will be glad you did.
"Everything indicates that the hydrogen originates in the moon's rocky core. We considered various ways hydrogen could leach from the rock and found that the most plausible source is ongoing hydrothermal reactions of rock containing minerals and organic materials," Dr. Waite noted in the April 13, 2017 SwRI Press Release. | 0.810908 | 3.341432 |
NASA’s Hubble Space Telescope has sent images of two tiny dwarf galaxies that have wandered from a vast cosmic wilderness into a nearby “big city” packed with galaxies, ahead of starting a firestorm of star birth.
After being quiescent for billions of years, the galaxies, called Pisces A and B, are late bloomers because they have spent most of their existence in the Local Void, a region of the universe sparsely populated with galaxies. The Local Void is roughly 150 million light-years across.
“These Hubble images may be snapshots of what present-day dwarf galaxies may have been like at earlier epochs,” said lead researcher Erik Tollerud of the Space Telescope Science Institute in Baltimore, Maryland. “Studying these and other similar galaxies can provide further clues to dwarf galaxy formation and evolution.”
The Hubble observations suggest that:
Under the steady pull of gravity from the galactic big city, the loner dwarf galaxies have at last entered a crowded region that is denser in intergalactic gas. In this gas-rich environment, star birth may have been triggered by gas raining down on the galaxies as they plow through the denser region.
Another idea is that the duo may have encountered a gaseous filament, which compresses gas in the galaxies and stokes star birth. Tollerud’s team determined that the objects are at the edge of a nearby filament of dense gas. Each galaxy contains only about 10 million stars.
Dwarf galaxies are the building blocks from which larger galaxies were formed billions of years ago in the early universe. Inhabiting a sparse desert of largely empty space for most of the universe’s history, these two galaxies avoided that busy construction period.
Pisces A is about 19 million light-years from Earth and Pisces B roughly 30 million light-years away. Tollerud’s team estimates that less than 100 million years ago, the galaxies doubled their star-formation rate. Eventually, the star formation may slow down again if the galaxies become satellites of a much larger galaxy.
“The galaxies could even probably stop forming stars altogether, because they will stop getting new gas to make stars,” Tollerud said. “So they will use up their existing gas. But it’s hard to tell right now exactly when that would happen, so it’s a reasonable guess that the star formation will ramp up at least for a while.”
Tollerud’s team hopes to observe other similar galaxies with Hubble. He also plans to scour the Panoramic Survey Telescope and Rapid Response System survey (PanSTARRS) for potential dwarf galaxies. Future wide-survey telescopes, such as the Large Synoptic Survey Telescope (LSST) in Chile and the large radio telescope in China, should be able to find many of these puny galactic neighbors.
The team’s results will appear in the Aug. 11 issue of The Astrophysical Journal. | 0.87038 | 4.064168 |
- 1.1.1. Plot a curve described by parametric equations.
- 1.1.2. Convert the parametric equations of a curve into the form
- 1.1.3. Recognize the parametric equations of basic curves, such as a line and a circle.
- 1.1.4. Recognize the parametric equations of a cycloid.
In this section we examine parametric equations and their graphs. In the two-dimensional coordinate system, parametric equations are useful for describing curves that are not necessarily functions. The parameter is an independent variable that both x and y depend on, and as the parameter increases, the values of x and y trace out a path along a plane curve. For example, if the parameter is t (a common choice), then t might represent time. Then x and y are defined as functions of time, and can describe the position in the plane of a given object as it moves along a curved path.
Parametric Equations and Their Graphs
Consider the orbit of Earth around the Sun. Our year lasts approximately 365.25 days, but for this discussion we will use 365 days. On January 1 of each year, the physical location of Earth with respect to the Sun is nearly the same, except for leap years, when the lag introduced by the extra day of orbiting time is built into the calendar. We call January 1 “day 1” of the year. Then, for example, day 31 is January 31, day 59 is February 28, and so on.
The number of the day in a year can be considered a variable that determines Earth’s position in its orbit. As Earth revolves around the Sun, its physical location changes relative to the Sun. After one full year, we are back where we started, and a new year begins. According to Kepler’s laws of planetary motion, the shape of the orbit is elliptical, with the Sun at one focus of the ellipse. We study this idea in more detail in Conic Sections.
Figure 1.2 depicts Earth’s orbit around the Sun during one year. The point labeled is one of the foci of the ellipse; the other focus is occupied by the Sun. If we superimpose coordinate axes over this graph, then we can assign ordered pairs to each point on the ellipse (Figure 1.3). Then each x value on the graph is a value of position as a function of time, and each y value is also a value of position as a function of time. Therefore, each point on the graph corresponds to a value of Earth’s position as a function of time.
We can determine the functions for and thereby parameterizing the orbit of Earth around the Sun. The variable is called an independent parameter and, in this context, represents time relative to the beginning of each year.
A curve in the plane can be represented parametrically. The equations that are used to define the curve are called parametric equations.
If x and y are continuous functions of t on an interval I, then the equations
are called parametric equations and t is called the parameter. The set of points obtained as t varies over the interval I is called the graph of the parametric equations. The graph of parametric equations is called a parametric curve or plane curve, and is denoted by C.
Notice in this definition that x and y are used in two ways. The first is as functions of the independent variable t. As t varies over the interval I, the functions and generate a set of ordered pairs This set of ordered pairs generates the graph of the parametric equations. In this second usage, to designate the ordered pairs, x and y are variables. It is important to distinguish the variables x and y from the functions and
Graphing a Parametrically Defined Curve
Sketch the curves described by the following parametric equations:
- To create a graph of this curve, first set up a table of values. Since the independent variable in both and is t, let t appear in the first column. Then and will appear in the second and third columns of the table.
t −3 −4 −2 −2 −3 0 −1 −2 2 0 −1 4 1 0 6 2 1 8
The second and third columns in this table provide a set of points to be plotted. The graph of these points appears in Figure 1.4. The arrows on the graph indicate the orientation of the graph, that is, the direction that a point moves on the graph as t varies from −3 to 2.
- To create a graph of this curve, again set up a table of values.
t −2 1 −3 −1 −2 −1 0 −3 1 1 −2 3 2 1 5 3 6 7
The second and third columns in this table give a set of points to be plotted (Figure 1.5). The first point on the graph (corresponding to has coordinates and the last point (corresponding to has coordinates As t progresses from −2 to 3, the point on the curve travels along a parabola. The direction the point moves is again called the orientation and is indicated on the graph.
- In this case, use multiples of for t and create another table of values:
t t 0 4 0 2 −2 0 −4 0 4 2 −2 2 2 4 0 −4 0
The graph of this plane curve appears in the following graph.
This is the graph of a circle with radius 4 centered at the origin, with a counterclockwise orientation. The starting point and ending points of the curve both have coordinates
Sketch the curve described by the parametric equations
Eliminating the Parameter
To better understand the graph of a curve represented parametrically, it is useful to rewrite the two equations as a single equation relating the variables x and y. Then we can apply any previous knowledge of equations of curves in the plane to identify the curve. For example, the equations describing the plane curve in Example 1.1b. are
Solving the second equation for t gives
This can be substituted into the first equation:
This equation describes x as a function of y. These steps give an example of eliminating the parameter. The graph of this function is a parabola opening to the right. Recall that the plane curve started at and ended at These terminations were due to the restriction on the parameter t.
Eliminating the Parameter
Eliminate the parameter for each of the plane curves described by the following parametric equations and describe the resulting graph.
- To eliminate the parameter, we can solve either of the equations for t. For example, solving the first equation for t gives
Note that when we square both sides it is important to observe that Substituting this into yields
This is the equation of a parabola opening upward. There is, however, a domain restriction because of the limits on the parameter t. When and when The graph of this plane curve follows.
- Sometimes it is necessary to be a bit creative in eliminating the parameter. The parametric equations for this example are
Solving either equation for t directly is not advisable because sine and cosine are not one-to-one functions. However, dividing the first equation by 4 and the second equation by 3 (and suppressing the t) gives us
Now use the Pythagorean identity and replace the expressions for and with the equivalent expressions in terms of x and y. This gives
This is the equation of a horizontal ellipse centered at the origin, with semimajor axis 4 and semiminor axis 3 as shown in the following graph.
As t progresses from to a point on the curve traverses the ellipse once, in a counterclockwise direction. Recall from the section opener that the orbit of Earth around the Sun is also elliptical. This is a perfect example of using parameterized curves to model a real-world phenomenon.
Eliminate the parameter for the plane curve defined by the following parametric equations and describe the resulting graph.
So far we have seen the method of eliminating the parameter, assuming we know a set of parametric equations that describe a plane curve. What if we would like to start with the equation of a curve and determine a pair of parametric equations for that curve? This is certainly possible, and in fact it is possible to do so in many different ways for a given curve. The process is known as parameterization of a curve.
Parameterizing a Curve
Find two different pairs of parametric equations to represent the graph of
First, it is always possible to parameterize a curve by defining then replacing x with t in the equation for This gives the parameterization
Since there is no restriction on the domain in the original graph, there is no restriction on the values of t.
We have complete freedom in the choice for the second parameterization. For example, we can choose The only thing we need to check is that there are no restrictions imposed on x; that is, the range of is all real numbers. This is the case for Now since we can substitute for x. This gives
Therefore, a second parameterization of the curve can be written as
Find two different sets of parametric equations to represent the graph of
Cycloids and Other Parametric Curves
Imagine going on a bicycle ride through the country. The tires stay in contact with the road and rotate in a predictable pattern. Now suppose a very determined ant is tired after a long day and wants to get home. So he hangs onto the side of the tire and gets a free ride. The path that this ant travels down a straight road is called a cycloid (Figure 1.9). A cycloid generated by a circle (or bicycle wheel) of radius a is given by the parametric equations
To see why this is true, consider the path that the center of the wheel takes. The center moves along the x-axis at a constant height equal to the radius of the wheel. If the radius is a, then the coordinates of the center can be given by the equations
for any value of Next, consider the ant, which rotates around the center along a circular path. If the bicycle is moving from left to right then the wheels are rotating in a clockwise direction. A possible parameterization of the circular motion of the ant (relative to the center of the wheel) is given by
(The negative sign is needed to reverse the orientation of the curve. If the negative sign were not there, we would have to imagine the wheel rotating counterclockwise.) Adding these equations together gives the equations for the cycloid.
Now suppose that the bicycle wheel doesn’t travel along a straight road but instead moves along the inside of a larger wheel, as in Figure 1.10. In this graph, the green circle is traveling around the blue circle in a counterclockwise direction. A point on the edge of the green circle traces out the red graph, which is called a hypocycloid.
The general parametric equations for a hypocycloid are
These equations are a bit more complicated, but the derivation is somewhat similar to the equations for the cycloid. In this case we assume the radius of the larger circle is a and the radius of the smaller circle is b. Then the center of the wheel travels along a circle of radius This fact explains the first term in each equation above. The period of the second trigonometric function in both and is equal to
The ratio is related to the number of cusps on the graph (cusps are the corners or pointed ends of the graph), as illustrated in Figure 1.11. This ratio can lead to some very interesting graphs, depending on whether or not the ratio is rational. Figure 1.10 corresponds to and The result is a hypocycloid with four cusps. Figure 1.11 shows some other possibilities. The last two hypocycloids have irrational values for In these cases the hypocycloids have an infinite number of cusps, so they never return to their starting point. These are examples of what are known as space-filling curves.
The Witch of Agnesi
Many plane curves in mathematics are named after the people who first investigated them, like the folium of Descartes or the spiral of Archimedes. However, perhaps the strangest name for a curve is the witch of Agnesi. Why a witch?
Maria Gaetana Agnesi (1718–1799) was one of the few recognized women mathematicians of eighteenth-century Italy. She wrote a popular book on analytic geometry, published in 1748, which included an interesting curve that had been studied by Fermat in 1630. The mathematician Guido Grandi showed in 1703 how to construct this curve, which he later called the “versoria,” a Latin term for a rope used in sailing. Agnesi used the Italian term for this rope, “versiera,” but in Latin, this same word means a “female goblin.” When Agnesi’s book was translated into English in 1801, the translator used the term “witch” for the curve, instead of rope. The name “witch of Agnesi” has stuck ever since.
The witch of Agnesi is a curve defined as follows: Start with a circle of radius a so that the points and are points on the circle (Figure 1.12). Let O denote the origin. Choose any other point A on the circle, and draw the secant line OA. Let B denote the point at which the line OA intersects the horizontal line through The vertical line through B intersects the horizontal line through A at the point P. As the point A varies, the path that the point P travels is the witch of Agnesi curve for the given circle.
Witch of Agnesi curves have applications in physics, including modeling water waves and distributions of spectral lines. In probability theory, the curve describes the probability density function of the Cauchy distribution. In this project you will parameterize these curves.
- On the figure, label the following points, lengths, and angle:
- C is the point on the x-axis with the same x-coordinate as A.
- x is the x-coordinate of P, and y is the y-coordinate of P.
- E is the point
- F is the point on the line segment OA such that the line segment EF is perpendicular to the line segment OA.
- b is the distance from O to F.
- c is the distance from F to A.
- d is the distance from O to B.
- is the measure of angle
The goal of this project is to parameterize the witch using as a parameter. To do this, write equations for x and y in terms of only
- Show that
- Note that Show that When you do this, you will have parameterized the x-coordinate of the curve with respect to If you can get a similar equation for y, you will have parameterized the curve.
- In terms of what is the angle
- Show that
- Show that
- Show that You have now parameterized the y-coordinate of the curve with respect to
- Conclude that a parameterization of the given witch curve is
- Use your parameterization to show that the given witch curve is the graph of the function
Travels with My Ant: The Curtate and Prolate Cycloids
Earlier in this section, we looked at the parametric equations for a cycloid, which is the path a point on the edge of a wheel traces as the wheel rolls along a straight path. In this project we look at two different variations of the cycloid, called the curtate and prolate cycloids.
First, let’s revisit the derivation of the parametric equations for a cycloid. Recall that we considered a tenacious ant trying to get home by hanging onto the edge of a bicycle tire. We have assumed the ant climbed onto the tire at the very edge, where the tire touches the ground. As the wheel rolls, the ant moves with the edge of the tire (Figure 1.13).
As we have discussed, we have a lot of flexibility when parameterizing a curve. In this case we let our parameter t represent the angle the tire has rotated through. Looking at Figure 1.13, we see that after the tire has rotated through an angle of t, the position of the center of the wheel, is given by
Furthermore, letting denote the position of the ant, we note that
Note that these are the same parametric representations we had before, but we have now assigned a physical meaning to the parametric variable t.
After a while the ant is getting dizzy from going round and round on the edge of the tire. So he climbs up one of the spokes toward the center of the wheel. By climbing toward the center of the wheel, the ant has changed his path of motion. The new path has less up-and-down motion and is called a curtate cycloid (Figure 1.14). As shown in the figure, we let b denote the distance along the spoke from the center of the wheel to the ant. As before, we let t represent the angle the tire has rotated through. Additionally, we let represent the position of the center of the wheel and represent the position of the ant.
- What is the position of the center of the wheel after the tire has rotated through an angle of t?
- Use geometry to find expressions for and for
- On the basis of your answers to parts 1 and 2, what are the parametric equations representing the curtate cycloid?
Once the ant’s head clears, he realizes that the bicyclist has made a turn, and is now traveling away from his home. So he drops off the bicycle tire and looks around. Fortunately, there is a set of train tracks nearby, headed back in the right direction. So the ant heads over to the train tracks to wait. After a while, a train goes by, heading in the right direction, and he manages to jump up and just catch the edge of the train wheel (without getting squished!).
The ant is still worried about getting dizzy, but the train wheel is slippery and has no spokes to climb, so he decides to just hang on to the edge of the wheel and hope for the best. Now, train wheels have a flange to keep the wheel running on the tracks. So, in this case, since the ant is hanging on to the very edge of the flange, the distance from the center of the wheel to the ant is actually greater than the radius of the wheel (Figure 1.15).
The setup here is essentially the same as when the ant climbed up the spoke on the bicycle wheel. We let b denote the distance from the center of the wheel to the ant, and we let t represent the angle the tire has rotated through. Additionally, we let represent the position of the center of the wheel and represent the position of the ant (Figure 1.15).
When the distance from the center of the wheel to the ant is greater than the radius of the wheel, his path of motion is called a prolate cycloid. A graph of a prolate cycloid is shown in the figure.
- Using the same approach you used in parts 1– 3, find the parametric equations for the path of motion of the ant.
- What do you notice about your answer to part 3 and your answer to part 4?
Notice that the ant is actually traveling backward at times (the “loops” in the graph), even though the train continues to move forward. He is probably going to be really dizzy by the time he gets home!
Section 1.1 Exercises
For the following exercises, sketch the curves below by eliminating the parameter t. Give the orientation of the curve.
For the following exercises, eliminate the parameter and sketch the graphs.
For the following exercises, use technology (CAS or calculator) to sketch the parametric equations.
For the following exercises, sketch the parametric equations by eliminating the parameter. Indicate any asymptotes of the graph.
For the following exercises, convert the parametric equations of a curve into rectangular form. No sketch is necessary. State the domain of the rectangular form.
where n is a natural number
For the following exercises, the pairs of parametric equations represent lines, parabolas, circles, ellipses, or hyperbolas. Name the type of basic curve that each pair of equations represents.
Show that represents the equation of a circle.
Use the equations in the preceding problem to find a set of parametric equations for a circle whose radius is 5 and whose center is
For the following exercises, use a graphing utility to graph the curve represented by the parametric equations and identify the curve from its equation.
An airplane traveling horizontally at 100 m/s over flat ground at an elevation of 4000 meters must drop an emergency package on a target on the ground. The trajectory of the package is given by where the origin is the point on the ground directly beneath the plane at the moment of release. How many horizontal meters before the target should the package be released in order to hit the target?
The trajectory of a bullet is given by where and When will the bullet hit the ground? How far from the gun will the bullet hit the ground?
[T] Use technology to sketch the curve represented by
[T] Use technology to sketch
Sketch the curve known as an epitrochoid, which gives the path of a point on a circle of radius b as it rolls on the outside of a circle of radius a. The equations are
[T] Use technology to sketch the spiral curve given by from
[T] Use technology to graph the curve given by the parametric equations This curve is known as the witch of Agnesi.
[T] Sketch the curve given by parametric equations where | 0.803469 | 3.778698 |
When is The Next Full Moon?Published on March 9th, 2015 | by Brandon Ramsey in Astronomy
While it may seem like the moon disappears and reappears on a monthly basis, it doesn’t go anywhere or change in size, at least not really. The lunar cycle culminates in the full illumination of the moon’s visible surface by the sun’s light. We call this phase a “full moon.”
Since this is the most visible our orbiting celestial body is from the Earth, you may be wondering when the next full moon is? Unfortunately it’s not as simple as asking “when is the next full moon” and naming a holiday’s date, but calculations done can provide us with an accurate time and date throughout each year.
Let’s find out when the full moon will appear throughout 2015, then we can discuss the various names for each month’s display, and more. Just like a waxing crescent moon, we’ve only just begun.
2015 Full Moon Schedule
A full moon is the lunar phase that happens when the Earth is between the sun and moon. The light illuminates the entire visible surface of the moon during this time. This phase is unique in that it represents the only time that so much of the surface is visible.
Despite this, the brightness of the illuminated moon makes it difficult to conduct any astronomical readings during this phase. Even so, this phase is the only time when a lunar eclipse is possible. These events don’t happen every month though because the angle of the moon’s orbit causes it to pass either above or below the Earth’s shadow.
The time it takes between full moon phases is known as a synodic month and it averages roughly 29.53 days. The elliptical nature of the moon’s orbit causes the actual date to shift. Given these calculations, here are the expected dates for 2015 to view full moons. Each time is recorded in Eastern Standard:
● January 4th – 11:53 pm
● February 3rd – 6:09 pm
● March 5th – 1:05 am
● April 4th – 8:06 am
● May 3rd – 11:42 pm
● June 2nd – 12:19 pm
● July 1st – 10:20 pm
● July 31st – 6:43 am (blue moon)
● August 29th – 2:35 pm
● September 27th – 10:50 pm
● October 27th – 8:05 am
● November 25th – 5:44 pm
● December 25th – 6:11 am
Full Moon Names and The Meanings Behind Them
Looking at the dates above, you may notice that July has two full moons this year. This only occurs in 7 out of every 19 years. The second moon in one month is what’s known as a “blue moon” which gave rise to the popular phrase “once in a blue moon.”
Another popular term in regards to a full moon is a “blood moon” which refers to the red color that the moon has during a total lunar eclipse. During this event the Earth’s shadow slowly covers the surface of the moon. When the process is complete the moon’s surface suddenly appears red.
The reason for this is the atmosphere that our planet has. During this event there is a ring of light around the Earth that allows the sun’s rays to pass through. As the light filters through our atmosphere, various frequencies of the light spectrum are affected. Red is the one that is least changed.
In fact, this color is refracted onto the Earth, then bounced back into the atmosphere, where it hits the moon during a total lunar eclipse, giving it that reddish color. Beyond these unique phenomena, the each month’s full moon was also given a name dating back to the times of Native American tribes.
Each full moon was named to better keep track of the seasons. For each month, there was a different name. Later on European settlers created similar names which are listed yearly in the Farmer’s Almanac. Those names and their explanations are listed below:
1. Wolf Moon – January
With January being a winter month, the Indian villages were constantly plagued by packs of wolves howling outside the borders. Other names for it included the Old Moon and the Moon After Yule.
2. Snow Moon – February
The heaviest snow usually falls in this month, which prompted the tribes in the northeast to create this name. An alternate name for it was the Full Hunger Moon because the weather made hunting extremely difficult.
3. Worm Moon – March
As winter begins to give way to spring, this full moon was given its name for the earthworms that begin to appear and attract feeding robins. Northern tribes called it the Full Crow Moon because the crows would begin to sound off when winter was ending. Other names included The Full Crust Moon, and the Lenten Moon over time.
4. Pink Moon – April
The name of this moon is attributed to the wild ground phlox which is one of the first flowers to bloom in spring and has a pinkish hue. Other names used were the Full Sprouting Grass Moon, the Egg Moon, and the Full Fish Moon.
5. Flower Moon – May
In May of each year, most flowers are in full bloom which prompted this name. Some other names were the Milk Moon and the Full Corn Planting Moon.
6. Strawberry Moon – June
The Native Americans of the time used this name, but the Europeans called it the Rose Moon. The original name was given because this month marks the season for strawberries each year.
7. Buck Moon – July
This month marks the time that most buck deer begin growing new antlers, which resulted in the name. It has also been called the Full Thunder Moon because of the thunderstorms that are common this time of year.
8. Sturgeon Moon – August
Native American tribes that focused on fishing chose this name because the sturgeon was most commonly caught in the Great Lakes during this time each year.
9. Corn Moon – September (Sometimes Known as Harvest Moon)
The first potential name for this moon is based on the fact that corn is harvested this time of the year. In two out of three years this moon occurs closest to the autumn equinox which makes it the Harvest Moon by tradition.
This name originated from the fact that farmers could work later during the peak times of harvest because of the light it provided.
10. Hunter’s Moon – October (Sometimes Known as Harvest Moon)
The primary name for this moon came about as a result of various tribes needing to stock up on food for the winter each year. In addition, this moon is sometimes referred to as the Harvest Moon because it falls closer to the autumn equinox than the September moon once every three years.
11. Beaver Moon – November
This moon came about just before swamps would freeze, which offered a final opportunity for tribes to set their beaver traps and use their fur for protection during the winter months. Another plausible origin is the fact that beavers prepare for winter during this month as well.
12. Cold Moon – December
This moon and its variations are named for the peak of winter cold and the longest nights for North American tribes each year. Other names include the Moon before Yule, and the Long Night Moon.
Common Beliefs Regarding the Lunar Effect
Knowing the answer to the question “when is the next full moon?” is something many people live by. There are a number of beliefs in various elements of society and human behavior that the full moon is responsible for changes in both behavior and biology.
The roots of these beliefs stem back to the ancient Assyrian and Babylonian writings. A common term, “Lunatic” actually is derived from the Latin word Luna which means “moon.” There are several common subjects that have been examined as potential areas where the full moon influences them.
These claims are, in many cases, not proven by scientific studies and when they are, a secondary or independent study reveals errors in the findings. We’ll examine a few scenarios so you can draw your own conclusions:
1. Human Fertility and Birth Rate
One common belief is that the full moon is somehow related to fertility because of the human menstrual cycle averaging 28 days. In addition, the full moon has also been associated with increased birth rates. Despite these claims, reviews of these studies have shown no relationship between these things and the full moon.
2. Human and Animal Behavior
Both animals and humans are believed to be affected by a full moon. Some studies have suggested that mentally ill patients exhibit increased violence and aggression during full moons, but these findings have since been challenged by a subsequent study.
In terms of animals, the reports are similar to the human ones in the sense that they are based on observation and not scientific studies.
3. Quality and Length of Sleep
A study in July of 2013 was conducted by the University of Basel in Switzerland that sought to examine the effects of lunar cycles on human sleep. Despite none of the patients knowing or seeing the moon, it was found that around the full moon, the brain activity during deep sleep decreased by as much as 30%
Without the patients knowing that the moon phases were a factor, unaware of where it was, and unable to see it, their sleeping patterns did indeed decrease in both length and quality during the full moon.
The possible explanations for some of these correlations are varied. Some believe that the same gravitational pull that affects the ocean tides also affects the human body because of the high water content. This has been disproved though because of the difference in scale between the oceans and the human body.
Despite these scientific studies disproving many of the claims, people still claim to see negative effects in behavior and other strange correlations.
Now, if you ever find yourself asking when is the next full moon, you will have a place to find the answer any month of the year. Thanks for reading and don’t forget to tell me about your thoughts on the full moon and its correlations in the comments below! | 0.820178 | 3.589652 |
Dust devils may roam hydrocarbon dunes on Saturn's moon Titan
Meteorological conditions on Saturn's large moon Titan, the strange, distant world that may be the most Earth-like in the solar system, appear conducive to the formation of dust devils, according to new research in AGU's journal Geophysical Research Letters.
The Cassini spacecraft, which toured Saturn's system from 2004 to 2017, observed dunes in the moon's equatorial region covering as much as 30% of the surface and a large dust storm.
The dust on Titan's dunes is believed to originate as hydrocarbon aerosols raining out of the moon's atmosphere, according to Brian Jackson, a planetary scientist at Boise State University in Idaho and the lead author of the new study. It likely has a plasticky texture unlike the more familiar grit found on Earth or Mars.
Rare, big dust storms look impressive, but dust devils loft more total dust into the atmosphere, even on Earth, where winds are more influential than on Mars or Titan.
"Winds at the surface of Titan are usually very weak. Unless there is a big storm rolling through, there's probably not that much wind, and so dust devils may be one of the main dust transport mechanisms on Titan—if they exist," Jackson said.
Dust devils have not been observed on Titan. The authors of the new study predicted the possible presence of dust devils by applying meteorological models to data acquired from the moon's surface during the brief visit of Cassini's Huygens probe in 2005.
Dust devils form in dry, calm conditions when sunlight warms the ground and near-surface air. Rising warm air creates vortices made visible by sand and dust caught up in the whirl. Dust devils share some physical properties with tornadoes but are always dry and do not grow as large and destructive. But scientists don't entirely understand how dust devils work.
"When we plug the numbers in for how much dust the dust devil ought to lift based on the wind speeds we see, they seem to be able to lift more dust than we would expect. There may be some other mechanism which is helping them pull this dust—or the equations are just wrong," Jackson said.
Jackson and his students have chased dust devils across southeastern Oregon's Alvord Desert with small airborne drones carrying meteorological instruments, in an ongoing effort to get a look inside.
Exceptionally dry conditions on the Red Planet beget many dust devils during Martian summers, when they can grow immense, reaching 8 kilometers (5 miles) high. Mars' atmosphere is so thin even 200-mile-an-hour winds only cause a gently buffeting. This makes the dust-lifting power of dust devils important to the global movement of dust on Mars.
"We can watch dust devils skitter across the surface of Mars and see what their internal structure is like, but that doesn't tell us how much dust they are lifting. Mars' atmosphere is really, really dusty and dust plays an important role in the climate. Dust devils are probably, if not the dominant mechanism, one of the most important mechanisms for lofting the dust," Jackson said.
If they exist on Titan, dust devils may be similarly important, although winds at the surface of Titan are typically gentle for the opposite reason: Titan's atmosphere is one and a half times the density of Earth's, but the moon has only one seventh of Earth's gravity. This makes Titan's atmosphere hard to get moving, according to Jackson.
"It's just this enormous, puffy atmosphere. When you've got that much air it's hard to get it churning. So you just don't usually get big winds on the surface of Titan so far as we know," said Jackson.
Like Earth's, Titan's atmosphere is mostly nitrogen, but it also includes influential amounts of ethane and methane, the major components of natural gas. Titan is the only world in the solar system other than Earth where scientists have observed evidence of flowing rivers and liquid surface lakes, but scientists believe these Earth-like features on the cold, distant moon are not water but liquid hydrocarbons.
Confirmation of the new study's dust devil prediction may have to wait on the arrival of NASA's Dragonfly mission in 2034. Jackson says buffeting from dust devil encounters would be unlikely to trouble the large octocopter as it explores the moon's surface. | 0.864549 | 3.958069 |
LISA is an astronomical observatory of unprecedented versatility and range.
LISA's all-sky field of view ensures observation in its frequency window of every gravitational wave source, without the need for targeting individual sources. Its coherent observation mode allows resolving and distinguishing overlapping signals and locating them on the sky.
LISA is designed to measure gravitational radiation over a broad band at low frequencies, from about 0.1 mHz to 1 Hz, a band where the Universe is richly populated by strong sources of gravitational waves.
LISA can achieve 10-20 strain resolution by measuring displacements of the order of a picometer. Its observations in the quiet environment of space will not be disturbed by seismic and gravity-gradient noise. Thus LISA's unparalleled sensitivity will allow studying sources within the Galaxy and out to the edge of the visible Universe.
LISA’s wide frequency band — four decades in frequency, equivalent to the span from near infrared to radio frequency in the electromagnetic sector — will enable astronomers to study similar sources of widely different masses and cosmological redshifts.
As gravitational waves propagate unhindered through all regions of time and space, LISA can sense waves from the densest regions of matter, the earliest stages of the Big Bang, and the most extreme warping of spacetime near black holes. In particular, LISA can observe objects that are shielded from electromagnetic observations by other stars or dust, such as binary systems close to or beyond the galactic center. | 0.828518 | 3.815643 |
The project "A CUTE Data sImulatoR aNd reDuction pipeLine" (ACUTEDIRNDL) is funded by the Austrian Research Promotion Agency (FFG) under the ASAP13 scheme and as part of the Austrian contribution to the CUTE mission.
The long-term evolution of a planetary atmosphere is predominantly controlled by escape, a process leading atmospheric gas to leave the planet's gravitational well and disperse into space. The ultraviolet (UV) transit observations of extra-solar planets conducted so far led to the detection of a large variety of phenomena, but, at present, the theories explaining them exceed the number of relevant transit observations. There is a whole wealth of phenomena, also variable in time, that requires a large observational effort to understand, effort that cannot be undertaken by the Hubble Space Telescope, which is our almost only UV “eye” and has now a very limited life-time.
Owing to the large size of the transiting atmospheres and to the short orbital periods of close-in planets, the physics of atmospheric mass-loss can be studied with a dedicated small instrument operating at near-UV wavelengths (250 - 320 nm). In 2017, NASA has approved funding to build, launch, and operate the Colorado Ultraviolet Transit Experiment (CUTE), which is a 6U CubeSat specifically designed to provide exactly the kind of spectroscopic observations that are urgently needed to further understand atmospheric escape.
We develop CUTE's data simulator, generate an exposure time and signal-to-noise calculator, and perform tests to foresee the effects of possible deviations from the nominal instrument alignment. We have simulated CUTE's optical system and performed ray tracing from the light source onto the CCD detector using point-like light sources with different spectral distributions and fluxes to simulate data obtained by observing different stellar types and magnitudes. The CUTE data simulator is used to construct synthetic CUTE transit datasets that are used to train the science team in the data analysis.
The project ended in October 2018.
Luca Fossati (PI)
Sreejith Aickara Gopinathan (main project postdoc/engineer)
Colorado Ultraviolet Transit Experiment data simulator.
Sreejith, A. G.; et al. (2019); JATIS. | 0.903051 | 3.283112 |
24.1 Introducing General Relativity
Einstein proposed the equivalence principle as the foundation of the theory of general relativity. According to this principle, there is no way that anyone or any experiment in a sealed environment can distinguish between free fall and the absence of gravity.
24.2 Spacetime and Gravity
By considering the consequences of the equivalence principle, Einstein concluded that we live in a curved spacetime. The distribution of matter determines the curvature of spacetime; other objects (and even light) entering a region of spacetime must follow its curvature. Light must change its path near a massive object not because light is bent by gravity, but because spacetime is.
24.3 Tests of General Relativity
In weak gravitational fields, the predictions of general relativity agree with the predictions of Newton’s law of gravity. However, in the stronger gravity of the Sun, general relativity makes predictions that differ from Newtonian physics and can be tested. For example, general relativity predicts that light or radio waves will be deflected when they pass near the Sun, and that the position where Mercury is at perihelion would change by 43 arcsec per century even if there were no other planets in the solar system to perturb its orbit. These predictions have been verified by observation.
24.4 Time in General Relativity
General relativity predicts that the stronger the gravity, the more slowly time must run. Experiments on Earth and with spacecraft have confirmed this prediction with remarkable accuracy. When light or other radiation emerges from a compact smaller remnant, such as a white dwarf or neutron star, it shows a gravitational redshift due to the slowing of time.
24.5 Black Holes
Theory suggests that stars with stellar cores more massive than three times the mass of the Sun at the time they exhaust their nuclear fuel will collapse to become black holes. The surface surrounding a black hole, where the escape velocity equals the speed of light, is called the event horizon, and the radius of the surface is called the Schwarzschild radius. Nothing, not even light, can escape through the event horizon from the black hole. At its center, each black hole is thought to have a singularity, a point of infinite density and zero volume. Matter falling into a black hole appears, as viewed by an outside observer, to freeze in position at the event horizon. However, if we were riding on the infalling matter, we would pass through the event horizon. As we approach the singularity, the tidal forces would tear our bodies apart even before we reach the singularity.
24.6 Evidence for Black Holes
The best evidence of stellar-mass black holes comes from binary star systems in which (1) one star of the pair is not visible, (2) the flickering X-ray emission is characteristic of an accretion disk around a compact object, and (3) the orbit and characteristics of the visible star indicate that the mass of its invisible companion is greater than 3 MSun. A number of systems with these characteristics have been found. Black holes with masses of millions to billions of solar masses are found in the centers of large galaxies.
24.7 Gravitational Wave Astronomy
General relativity predicts that the rearrangement of matter in space should produce gravitational waves. The existence of such waves was first confirmed in observations of a pulsar in orbit around another neutron star whose orbits were spiraling closer and losing energy in the form of gravitational waves. In 2015, LIGO found gravitational waves directly by detecting the signal produced by the merger of two stellar-mass black holes, opening a new window on the universe. | 0.872841 | 4.145968 |
Galileo Galilei (1564-1642) is considered the father of modern science and made major contributions to the fields of physics, astronomy, cosmology, mathematics and philosophy. Galileo invented an improved telescope that let him observe and describe the moons of Jupiter, the rings of Saturn, the phases of Venus, sunspots and the rugged lunar surface. His flair for self-promotion earned him powerful friends among Italy’s ruling elite and enemies among the Catholic Church’s leaders. Galileo’s advocacy of a heliocentric universe brought him before religious authorities in 1616 and again in 1633, when he was forced to recant and placed under house arrest for the rest of his life.
Galileo’s Early Life, Education and Experiments
Galileo Galilei was born in Pisa in 1564, the first of six children of Vincenzo Galilei, a musician and scholar. In 1581 he entered the University of Pisa at age 16 to study medicine, but was soon sidetracked by mathematics. He left without finishing his degree (yes, Galileo was a college dropout!). In 1583 he made his first important discovery, describing the rules that govern the motion of pendulums.
From 1589 to 1610, Galileo was chair of mathematics at the universities of Pisa and then Padua. During those years he performed the experiments with falling bodies that made his most significant contribution to physics.
Galileo had three children with Marina Gamba, whom he never married: Two daughters, Virginia (Later “Sister Maria Celeste”) and Livia Galilei, and a son, Vincenzo Gamba. Despite his own later troubles with the Catholic Church, both of Galileo’s daughters became nuns in a convent near Florence.
Galileo, Telescopes and the Medici Court
In 1609 Galileo built his first telescope, improving upon a Dutch design. In January of 1610 he discovered four new “stars” orbiting Jupiter—the planet’s four largest moons. He quickly published a short treatise outlining his discoveries, “Siderius Nuncius” (“The Starry Messenger”), which also contained observations of the moon’s surface and descriptions of a multitude of new stars in the Milky Way. In an attempt to gain favor with the powerful grand duke of Tuscany, Cosimo II de Medici, he suggested Jupiter’s moons be called the “Medician Stars.”
“The Starry Messenger” made Galileo a celebrity in Italy. Cosimo II appointed him mathematician and philosopher to the Medicis, offering him a platform for proclaiming his theories and ridiculing his opponents.
Galileo’s observations contradicted the Aristotelian view of the universe, then widely accepted by both scientists and theologians. The moon’s rugged surface went against the idea of heavenly perfection, and the orbits of the Medician stars violated the geocentric notion that the heavens revolved around Earth.
Galileo Galilei’s Trial
In 1616 the Catholic Church placed Nicholas Copernicus’s “De Revolutionibus,” the first modern scientific argument for a heliocentric (sun-centered) universe, on its index of banned books. Pope Paul V summoned Galileo to Rome and told him he could no longer support Copernicus publicly.
In 1632 Galileo published his “Dialogue Concerning the Two Chief World Systems,” which supposedly presented arguments for both sides of the heliocentrism debate. His attempt at balance fooled no one, and it especially didn’t help that his advocate for geocentrism was named “Simplicius.”
Galileo was summoned before the Roman Inquisition in 1633. At first he denied that he had advocated heliocentrism, but later he said he had only done so unintentionally. Galileo was convicted of “vehement suspicion of heresy” and under threat of torture forced to express sorrow and curse his errors.
Nearly 70 at the time of his trial, Galileo lived his last nine years under comfortable house arrest, writing a summary of his early motion experiments that became his final great scientific work. He died in Arcetri near Florence, Italy on January 8, 1642 at age 77 after suffering from heart palpitations and a fever.
What Was Galileo Famous For?
Galileo’s laws of motion, made from his measurements that all bodies accelerate at the same rate regardless of their mass or size, paved the way for the codification of classical mechanics by Isaac Newton. Galileo’s heliocentrism (with modifications by Kepler) soon became accepted scientific fact. His inventions, from compasses and balances to improved telescopes and microscopes, revolutionized astronomy and biology. Galilleo discovered craters and mountains on the moon, the phases of Venus, Jupiter’s moons and the stars of the Milky Way. His penchant for thoughtful and inventive experimentation pushed the scientific method toward its modern form.
In his conflict with the Church, Galileo was also largely vindicated. Enlightenment thinkers like Voltaire used tales of his trial (often in simplified and exaggerated form) to portray Galileo as a martyr for objectivity. Recent scholarship suggests Galileo’s actual trial and punishment were as much a matter of courtly intrigue and philosophical minutiae as of inherent tension between religion and science.
In 1744 Galileo’s “Dialogue” was removed from the Church’s list of banned books, and in the 20th century Popes Pius XII and John Paul II made official statements of regret for how the Church had treated Galileo | 0.859717 | 3.344333 |
WASHINGTON (Reuters) - Scientists are expected to unveil on Wednesday the first-ever photograph of a black hole, a breakthrough in astrophysics providing insight into celestial monsters with gravitational fields so intense no matter or light can escape.
The U.S. National Science Foundation has scheduled a news conference in Washington to announce a "groundbreaking result from the Event Horizon Telescope (EHT) project," an international partnership formed in 2012 to try to directly observe the immediate environment of a black hole.
Simultaneous news conferences are scheduled in Brussels, Santiago, Shanghai, Taipei and Tokyo.
A black hole's event horizon, one of the most violent places in the universe, is the point of no return beyond which anything - stars, planets, gas, dust, all forms of electromagnetic radiation including light - gets sucked in irretrievably.
While scientists involved in the research declined to disclose the findings ahead of the formal announcement, they are clear about their goals.
"It's a visionary project to take the first photograph of a black hole. We are a collaboration of over 200 people internationally," astrophysicist Sheperd Doeleman, director of the Event Horizon Telescope at the Center for Astrophysics, Harvard & Smithsonian, said at a March event in Texas.
The news conference is scheduled for 9 a.m. (1300 GMT) on Wednesday.
The research will put to the test a scientific pillar - physicist Albert Einstein's theory of general relativity, according to University of Arizona astrophysicist Dimitrios Psaltis, project scientist for the Event Horizon Telescope. That theory, put forward in 1915, was intended to explain the laws of gravity and their relation to other natural forces.
SUPERMASSIVE BLACK HOLES
The researchers targeted two supermassive black holes.
The first - called Sagittarius A* - is situated at the centre of our own Milky Way galaxy, possessing 4 million times the mass of our sun and located 26,000 light years from Earth. A light year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km).
The second - called M87 - resides at the centre of the neighbouring Virgo A galaxy, boasting a mass 3.5 billion times that of the sun and located 54 million light-years away from Earth. Streaming away from M87 at nearly the speed of light is a humongous jet of subatomic particles.
Black holes, coming in a variety of sizes, are extraordinarily dense entities formed when very massive stars collapse at the end of their life cycle. Supermassive black holes are the largest kind, devouring matter and radiation and perhaps merging with other black holes.
Psaltis described a black hole as "an extreme warp in spacetime," a term referring to the three dimensions of space and the one dimension of time joined into a single four-dimensional continuum.
Doeleman said the project's researchers obtained the first data in April 2017 from a global network of telescopes. The telescopes that collected that initial data are located in the U.S. states of Arizona and Hawaii as well as Mexico, Chile, Spain and Antarctica. Since then, telescopes in France and Greenland have been added to the network.
The scientists also will be trying to detect for the first time the dynamics near the black hole as matter orbits at near light speeds before being swallowed into oblivion.
The fact that black holes do not allow light to escape makes viewing them difficult. The scientists will be looking for a ring of light - radiation and matter circling at tremendous speed at the edge of the event horizon - around a region of darkness representing the actual black hole. This is known as the black hole's shadow or silhouette.
Einstein's theory, if correct, should allow for an extremely accurate prediction of the size and shape of a black hole.
"The shape of the shadow will be almost a perfect circle in Einstein's theory," Psaltis said. "If we find it to be different than what the theory predicts, then we go back to square one and we say, 'Clearly, something is not exactly right.'"
(Reporting by Will Dunham; Editing by Sandra Maler)
Did you find this article insightful? | 0.88576 | 3.153874 |
As we anxiously await the arrival of a potentially rich new meteor shower this weekend, its parent comet, 209P/LINEAR, draws ever closer and brighter. Today it shines feebly at around magnitude +13.7 yet possesses a classic form with bright head and tail. It’s rapidly approaching Earth, picking up speed every night and hopefully will be bright enough to see in your telescope very soon.
The comet was discovered in Feb. 2004 by the Lincoln Laboratory Near-Earth Asteroid Research (LINEAR) automated sky survey. Given its stellar appearance at the time of discovery it was first thought to be an asteroid, but photos taken the following month photos by Rob McNaught (Siding Spring Observatory, Australia) revealed a narrow tail. Unlike long period comets Hale-Bopp and the late Comet ISON that swing around the sun once every few thousand years or few million years, this one’s a frequent visitor, dropping by every 5.09 years.
209P/LINEAR belongs to the Jupiter family of comets, a group of comets with periods of less than 20 years whose orbits are controlled by Jupiter. When closest at perihelion, 209P/LINEAR coasts some 90 million miles from the sun; the far end of its orbit crosses that of Jupiter. Comets that ply the gravitational domain of the solar system’s largest planet occasionally get their orbits realigned. In 2012, during a relatively close pass of that planet, Jupiter perturbed 209P’s orbit, bringing the comet and its debris trails to within 280,000 miles (450,000 km) of Earth’s orbit, close enough to spark the meteor shower predicted for this Friday night/Saturday morning May 23-24.
This time around the sun, the comet itself will fly just 5.15 million miles (21 times the distance to the moon) from Earth around 3 a.m. CDT (8 hours UT) May 29 a little more than 3 weeks after perihelion, making it the 9th closest comet encounter ever observed. Given , you’d think 209P would become a bright object, perhaps even visible with the naked eye, but predictions call for it to reach about magnitude +11 at best. That means you’ll need an 8-inch telescope and dark sky to see it well. Either the comet’s very small or producing dust at a declining rate or both. Research published by Quanzhi Ye and Paul A. Wiegert describes the comet’s current dust production as low, a sign that 209P could be transitioning to a dormant comet or asteroid.
Fortunately, the moon’s out of the way this week and next when 209P/LINEAR is closest and brightest. Since we enjoy comets in part because of their unpredictability, maybe a few surprises will be in the offing including a brighter than expected appearance. The maps will help you track down 209P during the best part of its apparition. I deliberately chose ‘black stars on a white background’ for clarity in use at the telescope. It also saves on printer ink!
We’re grateful for the dust 209P/LINEAR carelessly lost during its many passes in the 19th and early 20th centuries. Earth is expected to pass through multiple filaments of debris overnight Friday May 23-24 with the peak of at least 100 meteors per hour – about as good as a typical Perseid or Geminid shower – occurring around 2 a.m. CDT (7 hours UT).
If it’s cloudy or you’re not in the sweet zone for viewing either the comet or the potential shower, astrophysicist Gianluca Masi will offer a live feed of the comet at the Virtual Telescope Project website scheduled to begin at 3 p.m. CDT (8 p.m. Greenwich Time) May 22. A second meteor shower live feed will start at 12:30 a.m. CDT (5:30 a.m. Greenwich Time) Friday night/Saturday morning May 23-24.
SLOOH will also cover 209P/LINEAR live on the Web with telescopes on the Canary Islands starting at 5 p.m. CDT (6 p.m. EDT, 4 p.m. MDT and 3 p.m. PDT) May 23. Live meteor shower coverage featuring astronomer Bob Berman of Astronomy Magazine begins at 10 p.m. CDT. Viewers can ask questions by using hashtag #slooh.
A very exciting weekend lies ahead! | 0.899773 | 3.883208 |
Using New Horizons data from the Pluto-Charon flyby in 2015, a Southwest Research Institute-led team of scientists have indirectly discovered a distinct and surprising lack of very small objects in the Kuiper Belt. The evidence for the paucity of small Kuiper Belt objects (KBOs) comes from New Horizons imaging that revealed a dearth of small craters on Pluto’s largest satellite, Charon, indicating that impactors from 300 feet to 1 mile (91 meters to 1.6 km) in diameter must also be rare.
The Kuiper Belt is a donut-shaped region of icy bodies beyond the orbit of Neptune. Because small Kuiper Belt objects were some of the “feedstock” from which planets formed, this research provides new insights into how the solar system originated. This research was published in the March 1 issue of the journal Science.
“These smaller Kuiper Belt objects are much too small to really see with any telescopes at such a great distance,” said SwRI’s Dr. Kelsi Singer, the paper’s lead author and a co-investigator of NASA’s New Horizons mission. “New Horizons flying directly through the Kuiper Belt and collecting data there was key to learning about both large and small bodies of the Belt.”
“This breakthrough discovery by New Horizons has deep implications,” added the mission’s principal investigator, Dr. Alan Stern, also of SwRI. “Just as New Horizons revealed Pluto, its moons, and more recently, the KBO nicknamed Ultima Thule in exquisite detail, Dr. Singer’s team revealed key details about the population of KBOs at scales we cannot come close to directly seeing from Earth.”
Craters on solar system objects record the impacts of smaller bodies, providing hints about the history of the object and its place in the solar system. Because Pluto is so far from Earth, little was known about the dwarf planet’s surface until the epic 2015 flyby. Observations of the surfaces of Pluto and Charon revealed a variety of features, including mountains that reach as high as 13,000 feet (4 km) and vast glaciers of nitrogen ice. Geologic processes on Pluto have erased or altered some of the evidence of its impact history, but Charon’s relative geologic stasis has provided a more stable record of impacts.
“A major part of the mission of New Horizons is to better understand the Kuiper Belt,” said Singer, whose research background studying the geology of the icy moons of Saturn and Jupiter positions her to understand the surface processes seen on KBOs. “With the successful flyby of Ultima Thule early this year, we now have three distinct planetary surfaces to study. This paper uses the data from the Pluto-Charon flyby, which indicate fewer small impact craters than expected. And preliminary results from Ultima Thule support this finding.”
Typical planetary models show that 4.6 billion years ago, the solar system formed from the gravitational collapse of a giant molecular cloud. The Sun, the planets and other objects formed as materials within the collapsing cloud clumped together in a process known as accretion. Different models result in different populations and locations of objects in the solar system.
“This surprising lack of small KBOs changes our view of the Kuiper Belt and shows that either its formation or evolution, or both, were somewhat different than those of the asteroid belt between Mars and Jupiter,” said Singer. “Perhaps the asteroid belt has more small bodies than the Kuiper Belt because its population experiences more collisions that break up larger objects into smaller ones.” | 0.894445 | 3.932086 |
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Entry 1017, on 2009-05-25 at 20:26:54 (Rating 1, Science)
It is now 100 years since the British scientist Arthur Eddington performed one of the most important experiments in modern physics which confirmed Einstein's Theory of General Relativity. He observed a total solar eclipse from the island of Principe, off the west African coast. Basically this confirmed that space (and time) really are bent by mass (in this case, the Sun) as Einstein predicted.
The reason we don't usually see this effect is that it is very small. Even a large mass like the Sun only distorts space a small amount so it was necessary to observe stars which were really close to the Sun (or appeared to be close because they were in line). Usually these stars aren't visible because the light the Sun is so much greater than the distant stars (even though the stars could easily be intrinsically brighter) so the eclipse was used to block the Sun's light.
OK, so there's my little history, physics and astronomy lesson but what is the point of all this? Well there are certain experiments, observations and theories which just keep coming up in discussions of science. These experiments are so revolutionary and far reaching that, even years after they were carried out, they still get mentioned in discussions of the relevant fields of science. So I started thinking about what other experiments might be in that category.
The first one I thought of, and another one which is very topical (because of the 150th anniversary of its publication), is the Theory of Evolution. This wasn't really the result of an experiment, it was more about careful and meticulous observation and recording, but I still think it ranks as one of the greatest scientific breakthroughs ever.
Another one which comes up a lot in physics and cosmology is the Michelson-Morley experiment. It was performed in 1887 by Albert Michelson and Edward Morley at what is now Case Western Reserve University. It was designed to detect the ether, which physicists at the time hypothesised the existence of because they needed a medium for wave phenomena, such as light, to travel through. The experiment showed the ether didn't exist, although this was so unexpected to some physicists that there were various attempts to rationalise the result.
A more modern example (and those are difficult because great experiments usually only become obvious after their influence has lasted many years) is the observations of the cosmic microwave background by various satellite observatories, especially the Wilkinson Microwave Anisotropy Probe (WMAP). This mission was launched on 30 June 2001 and helped establish many important characteristics of the Universe, including its age to an accuracy of 1%. WMAP is still working and recent observations of anomalous areas of low temperature could be very significant in the future.
Another older result would be Hubble's (I mean the astronomer, not the telescope which was named after him) observations which showed the Universe was expanding. I do seem to be mainly concentrating on physics and cosmology here but that has always been one of my major interests so I guess that's inevitable. Hubble performed some remarkable precision measurements of galaxies which showed they were all (or almost all) racing away from us. This showed the Universe was expanding which was contrary to what most people thought at the time (including Einstein).
I've got to mention one last experiment which is one of my favourites of all time. And it is related to quantum physics, of course! Its the infamous double slit experiment which demonstrates: how particles are waves and waves are particles, but maybe they're neither or both depending on the conditions; how one particle can be in two places at the same time; and how particles change their behaviour depending on whether they are being "watched" or not.
This experiment is still a mystery: not only can't we explain it but I don't think we even know what it means! Richard Feynman (one of the greatest quantum physicists) often said that all of quantum mechanics can be gleaned from carefully thinking through the implications of this single experiment.
Unfortunately, even though its been thought about a lot, quantum mechanics is not only the most successful theory but also the hardest to believe! It seems that reality at its deepest level seems totally unreal to humans who are used to thinking at the macroscopic level.
Finally, what will be the next great experiment? I think we need to know two things (again I'm sticking to the big picture - which is cosmology). First, what is dark matter and dark energy, and second (and most impotrant of all) how do we devise a theory which incorporates both quantum theory and relativity? Yes, its the old theory of everything again. We need an experiment to establish whether string theory or other alternatives can be used for the "theory of everything". There's no sign of that happening yet but one day it will.
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March 9, 2015 report
Cosmic radiation causes fluctuations in global temperatures, but doesn't cause climate change
(Phys.org)—Unlike electromagnetic radiation, which consists of massless and accelerated charged particles, galactic cosmic rays (CR) are composed mostly of atomic nuclei and solitary electrons, objects that have mass. Cosmic rays originate via a wide range of processes and sources including supernovae, galactic nuclei, and gamma ray bursts. Researchers have speculated for decades on the possible effects of galactic cosmic rays on the immediate environs of Earth's atmosphere, but until recently, a causal relationship between climate and cosmic rays has been difficult to establish.
A research collaborative has published a paper in the Proceedings of the National Academy of Sciences that mathematically establishes such a causal link between CR and year-to-year changes in global temperature, but has found no causal relationship between the CR and the warming trend of the 20th century.
Understanding cosmic radiation and global climate
In 1911, Charles Thomas Rees Wilson determined that ionizing radiation leads to atmospheric cloud nucleation. Increased cloudiness in the upper troposphere reduces long-wave radiation and results in warmer temperatures. Increased cloudiness in the lower troposphere leads to reduced incoming radiation, thereby decreasing global temperatures.
But the flux of cosmic rays interacting with the atmosphere is affected by the solar wind and Earth's own magnetic field. The solar wind, particularly at the region between the sun's termination shock and the heliopause, acts as a barrier to cosmic rays and decreases the flux of low-energy cosmic radiation. Earth's magnetic field deflects cosmic rays toward the poles, which produces the aurorae observed at certain latitudes. Therefore, researchers have theorized that the extent to which cosmic rays affect the Earth's climate depends on this combination of factors.
Going to the data
To study the effects of cosmic radiation on global temperature, the researchers compared two sets of data and devised a method to examine their causal connection. Past statistical analyses, while suggesting correlation of the effects of CR and temperature flux, were unable to actually establish causation. The authors applied a recently developed analytical method called convergent cross mapping (CCM) that was specifically designed to measure causality in nonlinear dynamical systems.
The data sets they analyzed included a CR proxy called the aa index that characterizes magnetic activity resulting from the interaction of the solar wind and Earth's magnetic field. In the set, a stronger solar wind and stronger magnetic disturbances yield a higher aa index. They compared it with the United Kingdom's Met Office HadCRUT3 data set of global temperature in the post-1900 period.
CCM helps to distinguish causality from spurious correlations in the time systems of dynamical systems, detecting whether two variables belong to the same dynamical system. If variable X is influencing variable Y, causality is established—but only if states of X can be recovered from the time series of Y. "Simply put," the authors write, "CCM measures the extent to which the historical record of the affected variable Y (or its proxies), reliably estimates states of causal variable X (or its proxies)."
Modestly cosmic results
The CCM method can identify both bidirectional causality (in which X and Y are mutually coupled) and unidirectional causality (in which X influences Y, but Y has no influence on X). The analysis produced the expected unidirectional causality between global temperature change and cosmic radiation—information about global temperature is not present in the cosmic radiation time series, but mapping from global temperature change to cosmic radiation succeeded, indicating that CR information was actually recoverable from analysis of GT fluctuations.
"Our results suggest weak to moderate coupling between CR and year-to-year changes of GT," they write. "However, we find that the realized effect is modest at best, and only recoverable when the secular trend in GT is removed." This "secular trend" is the warming widely believed to be caused by excess carbon in the atmosphere, an effect the researchers accounted for by first-differencing. "We show specifically that CR cannot explain secular warming, a trend that the consensus attributes to anthropogenic forcing. Nonetheless, the results verify the presence of a nontraditional forcing in the climate system, an effect that represents another interesting piece of the puzzle in our understanding of factors influencing climate variability," they write.
As early as 1959, it was hypothesized that an indirect link between solar activity and climate could be mediated by mechanisms controlling the flux of galactic cosmic rays (CR) [Ney ER (1959) Nature 183:451–452]. Although the connection between CR and climate remains controversial, a significant body of laboratory evidence has emerged at the European Organization for Nuclear Research [Duplissy J, et al. (2010) Atmos Chem Phys 10:1635–1647; Kirkby J, et al. (2011) Nature 476(7361):429–433] and elsewhere [Svensmark H, Pedersen JOP, Marsh ND, Enghoff MB, Uggerhøj UI (2007) Proc R Soc A 463:385–396; Enghoff MB, Pedersen JOP, Uggerhoj UI, Paling SM, Svensmark H (2011) Geophys Res Lett 38:L09805], demonstrating the theoretical mechanism of this link. In this article, we present an analysis based on convergent cross mapping, which uses observational time series data to directly examine the causal link between CR and year-to-year changes in global temperature. Despite a gross correlation, we find no measurable evidence of a causal effect linking CR to the overall 20th-century warming trend. However, on short interannual timescales, we find a significant, although modest, causal effect between CR and short-term, year-to-year variability in global temperature that is consistent with the presence of nonlinearities internal to the system. Thus, although CR do not contribute measurably to the 20th-century global warming trend, they do appear as a nontraditional forcing in the climate system on short interannual timescales.
© 2015 Phys.org | 0.805053 | 4.078002 |
Two separate research fields have been united in Hamburg for the very first time. Ultrashort laser pulses enable us to observe and manipulate matter on very short time scales, whereas ultracold atoms permit experiments with high precision and controllability. In the cluster of excellence “The Hamburg Centre for Ultrafast Imaging,” scientists from Universität Hamburg have united the two research fields and succeeded in observing the emergence of ions in ultracold atoms. Their findings have been published in the new scientific journal Communications Physics.
More than a century ago, Albert Einstein published his theoretical work on the photo-effect, which fundamentally describes the photoionization of matter, or the process of dissolving electrons from atoms by using light. This discovery earned him a Nobel Prize in 1921.
However, it turns out that the process is very complicated in detail. Up until now it has been nigh impossible to carry out experimental measurements of the absolute ionization probability, e.g., the percentage of atoms ionized after light irradiation.
The teams of scientists led by Prof. Dr. Markus Drescher and Prof. Dr. Klaus Sengstock have uniquely combined expertise in ultracold atoms with phenomena of ultrafast physics, which has opened up a fundamentally new experimental approach.
Ultrashort laser pulses can be so intense that they rip atoms apart. This process is called strong-field ionization and the details depend on the energy and color of the laser light. Up until now, it was not always possible to know which ionization regime dominates. The scientists have now succeeded in observing this in detail by using ultracold atoms. As there is hardly any atomic motion after the ionization process, it is possible to accurately measure the regimes.
The scientists used laser light to cool rubidium atoms to ultracold temperatures of 100 nanokelvins, only slightly above absolute zero temperature of -273.15° Celsius. An intense ultrashort laser pulse illuminated parts of the cloud of rubidium atoms for a very short time of 215 femtoseconds (a femtosecond is one millionth of one billionth of a second) and ionized a fraction of the atoms. The remaining atomic density was imaged onto a camera so that the amount of ionized atoms could be accurately measured.
In particular, the scientists observed that the atomic bond in an optical light field is modified so fast that the atomic shell cannot follow the oscillation of the light field. During ionization the atom thus absorbs multiple light particles (photons) simultaneously.
“The presented work paves the way towards further experiments using ultrashort laser pulses for creating ions and electrons in ultracold atomic samples,” lead author Philipp Wessels from Prof. Sengstock’s group explains.
“This leads to precise measurements of ultrafast processes by using ultracold atoms, because these systems can be controlled extremely well experimentally.” The results can also be used to help realize quantum computers based on ultracold ions. Such computers may solve certain problems faster than conventional ones.
Parallel to these experiments, an international collaboration with Prof. Nikolay Kabachnik (Moscow State University) and Prof. Andrey Kazansky (Ikerbasque, Spain) calculated the ionization process theoretically. The scientists modelled the quantum mechanical interaction between atom and laser field, with the following result: the theoretical predictions are in perfect agreement with the measured data.
P. Wessels, B. Ruff, T. Kroker, A. K. Kazansky,
N. M. Kabachnik, K. Sengstock, M. Drescher, and J. Simonet,
"Absolute strong-field ionization probabilities of ultracold rubidium atoms,"
Accepted in Communications Physics (new journal of the Nature group).
Link to the Journal: https://www.nature.com/commsphys/
Birgit Kruse | idw - Informationsdienst Wissenschaft
Silicon 'neurons' may add a new dimension to computer processors
05.06.2020 | Washington University in St. Louis
The broken mirror: Can parity violation in molecules finally be measured?
04.06.2020 | Johannes Gutenberg-Universität Mainz
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Two prominent X-ray emission lines of highly charged iron have puzzled astrophysicists for decades: their measured and calculated brightness ratios always disagree. This hinders good determinations of plasma temperatures and densities. New, careful high-precision measurements, together with top-level calculations now exclude all hitherto proposed explanations for this discrepancy, and thus deepen the problem.
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05.06.2020 | Life Sciences | 0.860921 | 3.335346 |
Even supermassive black holes can bite off more than they can chew, it seems, based on observations of a nearby pair of colliding galaxies.
A study analyzing emissions throughout the electromagnetic spectrum released by a nearby supermassive black hole gobbling up matter has revealed that even they can suffer from ‘indigestion’.
The mammoth body, weighing in at some 19 million times the mass of the Sun, lies at the center of a small galaxy named NGC 5195. Once every few hundred millions of years, NGC 5195 collides with the outer arms of its larger neighbor, known as NGC 5194 or (the more palatable) ‘Whirlpool’ galaxy. This happens because the two are locked in a gravitational wooing period that — in a few billion more years — will see them merge into a single galaxy.
But in the meantime, when these two galaxies touch, the supermassive black hole at the center of NGC 5195 picks up a lot of matter from Whirlpool into an accretion disk — so much matter, in fact, that it can’t absorb it all. But it still collapses onto the black hole since it’s subjected to enormous gravity. So all that excess matter eventually gets blown out into space. Last year, NASA’s Chandra X-Ray Observatory caught a whiff of X-ray emission that appeared to result from this process, but we didn’t really understand the how it happens.
Now, using high-resolution images of NGC 5195’s core taken with the e-MERLIN radio array, and drawing from archive images of the area taken with the Very Large Array (VLA), Chandra and the Hubble Space Telescope, a team of astronomers at the University of Manchester’s Jodrell Bank Centre for Astrophysics revealed the details of how these huge blasts of matter occur, and their behavior in space.
They report that when the accretion disk surrounding NGC 5195’s supermassive black hole breaks down, the immense forces and pressures involved create a shock wave which blasts all that matter back out into space — if you’re thinking this is kinda like how supernovae form, you’re pretty much on point.
Electrons, accelerated by this event close to the speed of light, interact with magnetic fields from neighboring bodies and emit energy in the radio wavelength spectrum. The X-ray emissions e-MERLIN picked up are created when the shock wave hits the gasses in the interstellar medium, inflating and heating them up. This process strips electrons from hydrogen gas atoms and ionizes them, creating the features seen by Chandra and Hubble.
“Comparing the VLA images at radio wavelengths to Chandra’s X-ray observations and the hydrogen-emission detected by Hubble, shows that features are not only connected, but that the radio outflows are in fact the progenitors of the structures seen by Chandra and Hubble,” explains Dr Hayden Rampadarath, who will be presenting his findings at the National Astronomy Meeting at the University of Hull explains.
“This is an event of galactic proportions that we can see right across the electromagnetic spectrum.”
According to him, the arcs seen in the NGC 5195 system are 1 to 2 million years old, meaning the first bits of matter were being pushed away from the black hole at about the same time as humans were learning how to make fire.
This isn’t the first time we’ve seen a black hole struggling to eat everything on its plate, and that event also had many of the features Dr Rampadarath identified here. Knowing this, it may be easier to spot overly-greedy black holes in the future. | 0.887849 | 4.132145 |
This year will bring a relative rare occurrence: four Full Moons before April 1, none of which occur in the month of February.
The cycle of lunar phases is determined by the particular alignment of the Moon and the Sun with Earth and this cycle has a period of approximately 29.5 days. This is the Moon’s synodic period, from the Greek συνοδος or sunodos, meaning a gathering. In this case the gathering is an alignment and the synodic period is the time between two identical alignments of three celestial objects. Thus the time between two Full Moons—when the Sun and Moon are exactly opposite each other as seen from Earth, is one synodic period or 29.5 days.
The first Full Moon of 2018 occurs on January 1. Although known by many different names across many cultures, this Full Moon is commonly referred to as the Full Moon After Yule or the Wolf Moon. The United States Naval Observatory provides a table of lunar phases for 2018. The times are given in Universal Time so corrects must be made based on your specific time zone. For example, while observing Standard Time, observers in the Midwestern United States must subtract six hours to get Central Standard Time and subtract five hours to get Central Daylight Time.
From the table we find that the first four Full Moons of 2018 occur on January 2 at 2hr 24m UT (8:24 p.m. on January 1 Central Standard Time), January 31 at 7:27 a.m. CST), March 1 at 6:51 p.m. CST, and March 31 at 6:37 a.m. CST.Since February is the only month that has less than 29 days, it is possible for no Full Moons to occur in February. This will occur when a Full Moon occurs on January 30 or 31.
With two Full Moons occurring in both January and March, there will be a lot of talk about Blue Moons. According to modern folklore, the second Full Moon that occurs within a single month is a Blue Moon. The phrase “once in a Blue Moon” supposedly signifies a rare event, but having two Blue Moons within three months doesn’t seem especially rare. In fact, according to this definition, which can be traced back to a misinterpretation of an earlier definition of Blue Moon (see my earlier post for details), two Full Moons can occur in one month about once every two years. That’s not especially rare. The fact that February has no Full Moon this year is more rare.
The alignment of our Gregorian calendar and the Moon’s synodic period synchronize to cause such an occurrence once every 19 years. Thus, the last year February had no Full Moon was 1999 and the next time this will happen is 2037. Even more rare, however, is a year in which a 29-day February has no Full Moon. In that case, not only must a Full Moon occur at the end of January, but the year must also be a leap year. The last leap year that had no Full Moon in February was 1608 (the year before Galileo acquire his first telescope!) The next leap year in which February has no Full Moon will be 2572. Now that is a rarity, indeed!
By the way, according to the more traditional definition of a Blue Moon described in the Maine Farmer’s Almanac (and described in a Sky & Telescope article), there are no Blue Moons in 2018. According to this definition, a season must have four Full Moons rather than the more typical three Full Moons. This year, the January 1 Full Moon is the Moon After Yule, the Full Moon on January 31 is the Snow Full Moon, and the Full Moon on March 1 is the Lenten Moon. The next Full Moon on March 31 occurs in spring and is the Egg Moon. The Full Moon occurring before the vernal equinox must be the Lenten Moon and if it is the fourth Full Moon of winter, the Full Moon falling between the Snow Moon and Lenten Moon is the Belewe, or Betrayer, Moon. That Full Moon must always fall between February 20 and 23 in order for another Full Moon to occur before the vernal equinox.
Much of the details surrounding the naming of Full Moons has to do with the determination of Easter since that is the most important moveable holiday on the Christian calendar and seasonal changes and the phases of the Moon had to be precisely determined. As with most things, once you dive deeply into the subject, you find that the rules are intricate and never are as simple as they seem initially. | 0.837722 | 3.682542 |
The Holy Grail in the search for extra-solar planets would be to find an Earth-like world orbiting another star. A group of UK astronomers believe they have good chance of being the first to find such a planet with a revolutionary new camera called RISE. With RISE, scientists will search for extra-solar planets using a technique called “transit timing,†which may provide a short-cut to discovering Earth-like planets with existing technology.
The two primary techniques to find extra-solar planets are usually only sensitive to massive, gas giant planets in close orbit around their parent star, so-called “Hot Jupiters.†Firstly, planets can be found through their gravitational pull on the star they orbit – as the extra-solar planet moves the star wobbles back and forth, and by measuring this movement astronomers can deduce the presence of a planet. Secondly, the transit search technique looks for the changes in a star’s brightness as a planet passes in front of it.
But neither of these techniques is currently good enough to find small extra-solar planets similar to the Earth. With the new transit timing technique, the RISE camera will look for Earth-mass planets in orbit around stars already known to host Hot Jupiters.
Transit timing works on the principle that an isolated hot Jupiter planet orbiting its host will have a constant orbital period (i.e. its ‘year’ remains the same) and therefore it will block out the light from its parent star in a regular and predictable way. During the planet’s transit events, RISE can very accurately measure the rise and fall in the amount of light reaching the Earth from the parent star – the camera can be used to pinpoint the time of the centre of the event to within 10 seconds. RISE is a fast-read camera. It has a fixed “V+R” filter and reimaging optics giving a 7 x 7 acrminute field of view to maximize the number of comparison stars available. An e2V frame transfer detector is used to obtain a cycle time of less than 1 second.
By observing and timing their transits, astronomers hope to detect small changes in the orbital periods of known hot Jupiters caused by the gravitational pull of other planets in the same system. In the right circumstances, even planets as small as the Earth could be found in this way.
“The potential of transit timing is the result of some very simple physics, where multi-planet systems will gravitationally kick one another around in their orbits – an effect often witnessed in our own Solar System,†said PhD student Neale Gibson of Queen’s University Belfast. “If Earth-mass planets are present in nearby orbits (which is predicted by current Hot-Jupiter formation theories) we will see their effect on the orbit of the larger transiting planets. RISE will allow us to observe and time the transits of extrasolar planets very accurately, which gives us the sensitivity required to detect the effect of even small Earth-mass planets.â€
RISE was designed by astronomers at Queen’s University in collaboration with Liverpool John Moores University and is now installed on the 2 meter Liverpool Telescope on the Canary Island of La Palma. For more information about the RISE Camera, see Neale Gibson’s homepage.
Original News Source: NAM Press Release | 0.866552 | 3.835184 |
Gas planets aren’t always bloated, monstrous worlds the size of Jupiter or Saturn (or larger) they can also apparently be just barely bigger than Earth. This was the discovery announced earlier today during the 223rd meeting of the American Astronomical Society in Washington, DC, when findings regarding the gassy (but surprisingly small) exoplanet KOI-314c were presented.
“This planet might have the same mass as Earth, but it is certainly not Earth-like,” said David Kipping of the Harvard-Smithsonian Center for Astrophysics (CfA), lead author of the discovery. “It proves that there is no clear dividing line between rocky worlds like Earth and fluffier planets like water worlds or gas giants.”
Discovered by the Kepler space telescope — ironically, during a hunt for exomoons — KOI-314c was found transiting a red dwarf star only 200 light-years away — “a stone’s throw by Kepler’s standards,” according to Kipping. (Kepler’s observation depth is about 3000 light-years.)
Kipping used a technique called transit timing variations (TTV) to study two of three exoplanets found orbiting KOI-314. Both are about 60% larger than Earth in diameter but their respective masses are very different. KOI-314b is a dense, rocky world four times the mass of Earth, while KOI-314c’s lighter, Earthlike mass indicates a planet with a thick “puffy” atmosphere… similar to what’s found on Neptune or Uranus.
Unlike those chilly worlds, though, this newfound exoplanet turns up the heat. Orbiting its star every 23 days, temperatures on KOI-314c reach 220ºF (104ºC)… too hot for water to exist in liquid form and thus too hot for life as we know it.
In fact Kipping’s team found KOI-314c to only be 30 percent denser than water, suggesting that it has a “significant atmosphere hundreds of miles thick,” likely composed of hydrogen and helium.
It’s thought that KOI-314c may have originally been a “mini-Neptune” gas planet and has since lost some of its atmosphere, boiled off by the star’s intense radiation.
Not only is KOI-314c the lightest exoplanet to have both its mass and diameter measured but it’s also a testament to the success and sensitivity of the relatively new TTV method, which is particularly useful in multiple-planet systems where the tiniest gravitational wobbles reveal the presence and details of neighboring bodies.
“We are bringing transit timing variations to maturity,” Kipping said. He added during the closing remarks of his presentation at AAS223: “It’s actually recycling the way Neptune was discovered by watching Uranus’ wobbles 150 years ago. I think it’s a method you’ll be hearing more about. We may be able to detect even the first Earth 2.0 Earth-mass/Earth-radius using this technique in the future.” | 0.859514 | 3.916099 |
Diamond xenolith and matrix organic matter in the Sutter’s Mill meteorite measured by C-XANES
Yoko Kebukawa, Michael E. Zolensky, A. L. David Kilcoyne, Zia Rahman, Peter Jenniskens and George D. Cody
Meteoritics & Planetary Science. doi: 10.1111/maps.12312
Article first published online: 13 OCT 2014
The Sutter’s Mill (SM) meteorite fell in El Dorado County, California, on April 22, 2012. This meteorite is a regolith breccia composed of CM chondrite material and at least one xenolithic phase: oldhamite. The meteorite studied here, SM2 (subsample 5), was one of three meteorites collected before it rained extensively on the debris site, thus preserving the original asteroid regolith mineralogy. Two relatively large (10 μm sized) possible diamond grains were observed in SM2-5 surrounded by fine-grained matrix. In the present work, we analyzed a focused ion beam (FIB) milled thin section that transected a region containing these two potential diamond grains as well as the surrounding fine-grained matrix employing carbon and nitrogen X-ray absorption near-edge structure (C-XANES and N-XANES) spectroscopy using a scanning transmission X-ray microscope (STXM) (Beamline 5.3.2 at the Advanced Light Source, Lawrence Berkeley National Laboratory). The STXM analysis revealed that the matrix of SM2-5 contains C-rich grains, possibly organic nanoglobules. A single carbonate grain was also detected. The C-XANES spectrum of the matrix is similar to that of insoluble organic matter (IOM) found in other CM chondrites. However, no significant nitrogen-bearing functional groups were observed with N-XANES. One of the possible diamond grains contains a Ca-bearing inclusion that is not carbonate. C-XANES features of the diamond-edges suggest that the diamond might have formed by the CVD process, or in a high-temperature and -pressure environment in the interior of a much larger parent body. | 0.851016 | 3.010386 |
Was Mercury once habitable?
When it comes to the possibility of life elsewhere in our solar system, Mercury is easily one of the last places you’d think of. Being the closest planet to the sun – with no true atmosphere – it is a broiling, uninhabitable place of desolation. But was it always like that? As unlikely as it seems, a new study announced by researchers at the Planetary Science Institute (PSI) suggests that some regions in Mercury’s subsurface might have once been hospitable enough for prebiotic chemistry or – perhaps – even simple microscopic lifeforms.
The study focuses on Mercury’s chaotic terrain (aka its weird terrain): vast, cratered and “knobby” landscapes first seen by the Mariner 10 flybys in 1974. There are evolving ideas on how it came to be, but – according to the new study – this terrain was created by the removal of massive amounts of volatiles – chemical elements and compounds with low boiling points – in Mercury’s upper crust (and not simply seismic disturbances from the Caloris Basin impact as long thought).
The chaotic terrain studied is antipodal – on the direct opposite side of the planet from – the Caloris Basin. The new analysis is based on much higher-resolution images taken later by the MESSENGER spacecraft. From the paper:
Mercury’s images obtained by the 1974 Mariner 10 flybys show extensive cratered landscapes degraded into vast knob fields, known as chaotic terrain (AKA hilly and lineated terrain). For nearly half a century, it was considered that these terrains formed due to catastrophic quakes and ejecta fallout produced by the antipodal Caloris Basin impact. Here, we present the terrains’ first geologic examination based on higher spatial resolution MESSENGER (MErcury Surface Space ENvironment GEochemistry and Ranging) imagery and laser altimeter topography. Our surface age determinations indicate that their development persisted until ~1.8 Ga, or ~2 Gyrs after the Caloris Basin formed.
Furthermore, we identified multiple chaotic terrains with no antipodal impact basins; hence a new geological explanation is needed. Our examination of the Caloris Basin’s antipodal chaotic terrain reveals multi-kilometer surface elevation losses and widespread landform retention, indicating an origin due to major, gradual collapse of a volatile-rich layer. Crater interior plains, possibly lavas, share the chaotic terrains’ age, suggesting a development associated with a geothermal disturbance above intrusive magma bodies, which best explains their regionality and the enormity of the apparent volume losses involved in their development. Furthermore, evidence of localized, surficial collapse, might reflect a complementary, and perhaps longer lasting, devolatilization history by solar heating.
The findings mean that Mercury had a thick volatile-rich – possibly but not necessarily water-rich – crust in this location. Mercury’s surface temperature reaches a scorching 430 degrees Celsius [800 degrees Fahrenheit] during the daytime, and in the absence of an atmosphere, it plummets to -180 degrees Celsius [-290 F] at night. So, its surface environments have rightfully been out of scientific consideration as a possible host of life. However, the paper raises the prospect that some subsurface regions of Mercury have shown capacity for hosting life.
The materials in the chaotic terrains were once part of geologic deposits deep underground, where crustal volatiles would have been protected. Those volatiles could have included water or water ice. PSI coauthor Daniel Berman said:
The deep valleys and enormous mountains that now characterize the chaotic terrains were once part of volatile-rich geologic deposits a few kilometers deep, and do not consist of ancient cratered surfaces that were seismically disturbed due to the formation of Mercury’s Caloris impact basin on the opposite side of the planet, as some scientists had speculated. A key to the discovery was the finding that the development of the chaotic terrains persisted until approximately 1.8 billion years ago, 2 billion years after the Caloris Basin formed.
Another coauthor, Gregory Leonard at the University of Arizona, said:
We identified multi-kilometer surface elevation losses within the chaotic terrains located at the Caloris Basin’s antipode. This finding indicates that enormous volumes of crustal volatiles turned into gas and escaped the planet’s upper crust over a surface area slightly larger than that of California, approximately 500,000 square kilometers [200,000 sq miles].
As Rodriguez also noted, the chaotic terrains on Mercury appear to be global, and might be found elsewhere as well, on Mercury-like exoplanets:
Our investigation also shows that there are also numerous extensive chaotic terrains in other regions of the planet, which have latitudinal distributions ranging from equatorial to subpolar. Hence, Mercury’s volatile-rich crust appears to be greater than regional, perhaps global, in extent, and it is most likely made up of compositionally diverse volatile compounds. The apparent compositional diversity suggests that the planet’s upper crust might effectively be comprised of a large number of compositional and thermal conditions, some perhaps habitable, existing in Mercury-like exoplanets.
But just how did the crustal volatiles get released from the subsurface? According to PSI scientist Kevin Webster, it was most likely due to volcanoes:
Vast lava fields formed soon after the development of the chaotic terrains, so volcanic heat could have destabilized and released the apparently vast volumes of crustal volatiles.
As for how Mercury obtained its volatiles in the first place, PSI scientist and coauthor Jeff Kargel added:
We also observe evidence of surficial devolatilization, probably caused by solar heating. If so, we have an opportunity to infer the range of Mercury’s volatile properties and compositions. A possibility is that Mercury’s volatile-rich crust was delivered via impacts from the frigid confines of the outer solar system or the main asteroid belt. Alternatively, volatiles were outgassed from the interior.
The researchers also noted that volatiles could have still been escaping from Mercury’s subsurface even much more recently, perhaps even still going on to this day. As Rodriguez noted:
Evidence of recent, and perhaps on-going, volatile losses from within near-surface geologic materials on Mercury has been previously documented through the investigation of small depressions known as hollows, which kind of resemble melt pits in terrestrial permafrost. However, an unresolved issue remains the age disparity between these hollows and their volatile-bearing geologic units, which are thought to be billions of years old. Our results suggest that some hollows might represent the locations where lavas or sublimation lags covering these ancient geologic materials underwent collapse. This is exciting because their distribution might highlight areas where we can effectively access volatile-rich material, that after billions of years existing in the subsurface, have been finally been exposed to the surface.
If Mercury’s early volatiles did include water or ice – something still unknown – then conceivably the planet could have had habitable niches in its subsurface. According to Kargel:
While not all volatiles make for habitability, water ice can if temperatures are right. Some of Mercury’s other volatiles may have added to the characteristics of a former aqueous niche. Even if habitable conditions existed only briefly, relics of prebiotic chemistry or rudimentary life still might exist in the chaotic terrains.
We also know that water ice still exists on Mercury today, in deep polar craters that are always in permanent shadow, and therefore much colder since there is no atmosphere to distribute heat from the sunlit regions. As PSI scientist Mark Sykes said:
If these results are confirmed, this and other similar areas of collapse on Mercury could be important considerations for future landing sites to investigate the origin of the planet’s volatile-rich crust and, perhaps, even its astrobiological potential.
The idea that Mercury could have supported life, or at least prebiotic chemistry, sounds outlandish at first thought, but – just maybe – this scorching, airless little world wasn’t always as inhospitable as it is now, at least underground.
Bottom line: Habitable conditions may have once existed in Mercury’s subsurface, according to a new study from the Planetary Science Institute. | 0.868798 | 3.910033 |
Scientists at the University of Oxford said Monday they believe they have discovered the site of the biggest meteorite impact ever to hit the British Isles.
Evidence for the 1.2 billion-year-old meteorite strike was first discovered in 2008 near Ullapool in the north west of Scotland, by scientists from Oxford and Aberdeen Universities.
The thickness and extent of the debris deposit they found suggested the impact crater, made by a meteorite estimated at 1 km wide, was close to the coast, but until now its precise location remained a mystery.
Ken Amor from the Department of Earth Sciences at Oxford University outlined their work in a paper published in Journal of the Geological Society, explaining how they have identified the crater location 15-20 km west of a remote part of the Scottish coastline. It is buried beneath both water and younger rocks in what is known as the Minch Basin.
“The material excavated during a giant meteorite impact is rarely preserved on Earth, because it is rapidly eroded, so this is a really exciting discovery. It was purely by chance this one landed in an ancient rift valley where fresh sediment quickly covered the debris to preserve it,” Amor said.
According to him, the next step will be a detailed geophysical survey in the target area of the Minch Basin.
Using a combination of field observations, the distribution of broken rock fragments known as basement clasts and the alignment of magnetic particles, the team was able to gauge the direction the meteorite material took at several locations, and plotted the likely source of the crater.
“It would have been quite a spectacle when this large meteorite struck a barren landscape, spreading dust and rock debris over a wide area,” Amor added.
Scientists believe the Earth and other planets may have suffered a higher rate of meteorite impacts in the distant past, as they collided with debris left over from the formation of the early solar system.
“There is a possibility that a similar event will happen in the future given the number of asteroid and comet fragments floating around in the solar system. Much smaller impacts, where the meteorite is only a few meters across are thought to be relatively common perhaps occurring about once every 25 years on average,” said the report of Amor and his team, speculating about future strikes, added:
It is thought that collisions with an object about 1 km, as in the case of the Scotland strike, across occur between once every 100,000 years to once every 1 million years — but estimates vary.
“One of the reasons for this is that our terrestrial record of large impacts is poorly known because craters are obliterated by erosion, burial and plate tectonics,” the report said.
Jupiter’s internal magnetic field is changing over time, a phenomenon observed by the U.S. National Aeronautics and Space Administration (NASA) for the first time outside of the Earth, the agency has said. The phenomenon, called […]
The German government should spend significantly more money on space travel, according to a policy paper published by the Federation of German Industries (BDI) on Tuesday. According to the BDI, space travel “contributes significantly to […] | 0.860559 | 3.686047 |
Investigating the Insides
Investigating the Insides is a 30–minute activity in which teams of children, ages 10 to13, investigate the composition of unseen materials using a variety of tools. This open-ended engagement activity mimics how scientists discover clues about the interiors of planets with cameras and other instruments onboard spacecraft.
What's the Point?
- The interior of a planet cannot be studied directly; scientists must infer the composition and structure from their observations.
- Different instruments provide different forms of indirect evidence.
- Scientists use their observations (evidence) to build on what they already know about the universe.
- Scientific explanations are built on existing evidence and models. New technologies help scientists find new evidence and construct new models. Science advances when these are incorporated into our knowledge of the universe.
- Models offer a useful way to explore properties of the natural world.
For each group of 20 to 30 children:
- 5–7 extra-large dark blue balloons filled with air and other assorted materials (below)
- 2 compasses or magnets
- 1-3 strong magnets, such as cow magnets (available from pet/farm supply stores or science education product retailers)
- Scraps of paper
- 10-20 beads
- 5-10 marbles
- Optional: Whipped cream from a bottle with a nozzle
- Optional: Water
- 2 small scales (such as postage scales)
- 2 liquid crystal temperature strips (available in most pet stores or stores that sell aquarium fish)
- 2 magnifying glasses
- Optional: 2 laser pointers
- Optional: 2 ear thermometers
For each child:
- His/her My Trip to Jupiter Journal or just the relevant "Investigating the Insides" page
- 1 pencil or pen
For the facilitator:
- Review the background information.
- Prepare the balloons: After stretching out the balloon, place a magnet, one or more paperclips, several beads, or several marbles in it and inflate it. Repeat for each balloon. If possible, add some water to several of the balloons and then finish inflating them before tying the ends. Tie a secure knot in the end of each balloon.
- Set out the remainder of the materials on a variety of tables for the children to use.
1. Ask the children how scientists study planets.
- Are there different tools we can use to study planets? We can use telescopes, and can send robotic spacecraft to the planets. There are different instruments on spacecraft and on telescopes, like cameras and sophisticated detectors, that can be used to study planets.
- How can we study what's inside a planet? No instruments can "see" inside a planet. We need to use indirect methods to study planetary interiors.
Scientists study the interiors through models they create, which are based on a planet's observable characteristics. Earth's interior is studied in part through seismic data. The giant planets and Earth all have magnetic fields, which are detectable by the radio signals they emit. Magnetic fields are generated deep within planets, so they provide clues to the internal structure and composition. Orbiting spacecraft experience slight variations in their trajectories that help scientists understand a planet's gravity well. By measuring the gravitational pull, scientists can tell more about how a planet's heavy material is distributed in its interior. That information will help them make educated inferences about a planet's composition.
2. Share that the Juno mission launched in 2011 to study Jupiter.
- One of its goals is to study Jupiter's structure using different kinds of sophisticated instruments. Juno will measure the atmosphere's temperature and amounts of water and ammonia at different depths. This information will help scientists understand the winds deep in Jupiter's atmosphere and piece together Jupiter's internal structure. JunoCam will take pictures of the planet, which scientists and studentswill use to study the poles. Juno will study Jupiter's magnetic field. It has cameras and sensors that will study Jupiter in visible light, in ultraviolet, infrared, and radio. It will keep track of how its orbit is slightly changed by the amount of pull from Jupiter; this will provide clues about Jupiter's gravity field. While some of these instruments will provide clues about the inside of Jupiter, none of them will be able to see inside the planet.
3. Tell the children that they are going to explore how we study planets, using balloons as models.
- What's a model?
- How does a planet compare with a balloon? We can only see the surfaces or outer layers of planets, just like we can only see the outside of a balloon.
- What are some ways we can determine what is inside of these balloons? We can feel the balloons and shake them. We can use tools like thermometers, scales, magnets, and compasses to learn more about what's inside the balloon.
4. Invite the children to divide into groups of four and use their senses and the tools in the room to investigate their balloons. Each child or group should write down their observations in their journals. They must be careful not to pop the balloons, but they are allowed to use their senses and other tools to study their "planets." Have each team record a hypothesis about what is inside their balloon in their journals.
5. One at a time, invite each group to share their observations with the others. Ask the groups to share their hypothesis on what is inside of their balloons.
- What materials do they think are inside their balloons? Are they hard (solid), sloshy (liquid), or feel like a normal balloon (filled with gas)?
Ask the children to compare their balloons to planets.
- How are the planets like the balloons? We can't see inside a planet or inside a dark balloon. We inferred what was inside.
- What tools did you use to tell what was inside your balloon? Children might have used the scale to weigh the balloon, compared its weight with familiar objects, and listened to the noises when they shook it, among other things.
- Can scientists do all of these things to a distant planet? Can they shake it, pick it up, or weigh it? No.
- How might a scientist study a planet? What kind of tools should a spacecraft have to study a planet? They can see if the planet has a magnetic field with something like a compass or magnet. They can measure its mass by seeing how much it pulls on an object like a spacecraft. The strength of a planet's gravitational pull for its size can help scientists understand whether gases, liquids, or solids make up the planet's insides. They can examine the outside to study its composition.
Reiterate that Juno will investigate Jupiter — like the children did with their balloons — using a variety of sophisticated instruments.
Facilitator's Note: Juno will use sophisticated instruments, such as a microwave radiometer and magnetometer. For more information about the instruments onboard the Juno spacecraft, visit http://www.nasa.gov/mission_pages/juno/spacecraft/.
Invite the children to pop their balloons to test their hypotheses (outside if there is water or whipped cream in any balloon).
Share with the children that scientists can never see exactly what is a planet or how its inside materials are arranged. Scientists cannot "pop" the planet to see if they are right! Their interpretation is based on the evidence they gathered. Their interpretation may be altered in the future as more evidence is collected, or new instruments are created.
If possible, build on the children's knowledge by offering them a future Jupiter's Family Secrets activity. Ten-year-old children may wrap-up their investigations of Jupiter by attending the concluding activity, My Trip to Jupiter, where they create scrapbooks to document their own journeys into Jupiter's deepest mysteries! Invite children ages 11 to 13 to return for the next program and use some of these tools to investigate Neato-Magneto Planets! | 0.862265 | 3.138265 |
Cheers erupted from the UC Berkeley Space Sciences Laboratory on Sunday evening as a spacecraft designed largely by UC Berkeley researchers successfully fell into orbit around Mars.
The Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft recently completed its 10-month-long journey to Earth’s nearest neighbor and will officially begin its mission to study Mars’ evolution from a warm and wet planet into the seemingly inhospitable one it has become.
Researchers hope to find an explanation for the thinning of the martian atmosphere by detecting radiation and solar wind interactions and tracking escaping particles in Mars’ upper atmosphere. UC Berkeley researchers have collaborated for several years with scientists at the University of Colorado Boulder to design instruments and track MAVEN’s progress.
Campus researcher Gregory Delory remembered the moment of arrival as one of “relief and elation.”
“You’re really excited, because you’ve realized everything you’ve worked for is going to happen,” he said. “I like to stay optimistic, but orbit insertion is the second-most-dangerous thing aside from launch, so it’s not to be taken lightly.”
Scientists will now spend the next six weeks deploying various mechanisms to optimize MAVEN’s orbital operation. By the first week of November, it will have officially started systematic data collection.
The data, to be collected and archived in three-month intervals, will be made available to the public in hopes of drawing analyses from scientists worldwide.
G. Scott Hubbard, a consulting professor of aeronautics and astronautics at Stanford University, called MAVEN a “time machine” that would fill a very important piece in the puzzle of Mars’ history.
“The science is truly fundamental, because knowing the answer to the big question — ‘Are we alone?’ — requires space missions to answer, and Mars is the best place to look for the potential past emergence of life,” Hubbard said.
He reasoned that because the spacecraft has already passed two major milestones — launch and orbit entrance — there is a high likelihood that it may be the latest addition to the few successful missions to Mars.
If successful, MAVEN could provide insight into how planets form and how they evolve.
“An interesting question would be what would happen to Earth if we lost our magnetic field — would we have lost our atmosphere?” Delory said. “It’s kind of a preview of what could’ve happened to us if we weren’t so special here.”
One unexpected bump in the road may arise from a comet, Siding Spring, to draw near Mars soon. While scientists are not too concerned with hazards it may create for the spacecraft, they will be shutting down some instruments for about a week upon its arrival and using others to measure potential changes.
“We already have a special experiment that we hadn’t planned, courtesy of mother nature,” said principal investigator Janet Luhmann.
While the mission is currently funded by NASA for only one year, co-investigator Robert Lillis said the researchers will be applying for an extension, explaining that the spacecraft has enough fuel to last it several more years. If granted, scientists would be able to paint a much broader picture of a planet that, he said, will almost inevitably house humans. | 0.836812 | 3.579824 |
The Parker Solar Probe will be the first spacecraft to ‘deep dive’ into the Sun's atmosphere so it can study its corona, getting closer to the Sun than any other mission ever has. It will orbit the Sun 24 times and pass by Venus seven times, using the gravity of the planet to slow the spacecraft down a little bit each time so it can pass closer to the Sun. NASA plans to launch the spacecraft sometime between July 31 and August 20 next year. It will take just three months to make the first flyby of the Sun. It will come closest to the Sun on December 19, 2024. Travelling at more than 720,000 kilometres per hour, the probe will eventually come within less than 6.4 million kilometres of the Sun's surface. This may not sound very close, but if you think of the Sun and Earth as being one metre apart, then the craft would be located just 4 centimetres from the Sun. The probe will be in regions of the corona where temperatures exceed 1,400 degrees Celsius.
The two big questions scientists are asking are:
- Why is the corona on the outside of the Sun at least 300 times hotter than the surface?
- Why does the solar wind speed up?
These questions are important because we literally live in the atmosphere of the Sun. This outer region gets accelerated and moves away from the Sun, bathing all of the planets. When large events such as sunspots or coronal mass ejections happen, they can have dramatic effects on our planet, causing spectacular aurorae but also disrupting communication systems. Understanding solar winds is also integral to understanding how much radiation we could be exposed to in space.
The probe is about 3m tall and weighs about 685kg. A white light imager will analyse the solar wind in front of the spacecraft so scientists can "see" what the other instruments are about to detect. The front of the spacecraft will have a shield, 2.3 metres wide and 11 centimetres thick, made up of a special carbon foam sandwiched between two thin sheets. The front face will be covered in aluminium oxide to reflect light and heat. So while the shield will get up to 1,400C, the instruments inside will stay at room temperature.
Source Reference: http://www.abc.net.au/news/science/2017-06-01/parker-solar-probe-nasas-journey-to-touch-the-sun/8572540
Featured image at top of page: (Supplied: Johns Hopkins University Applied Physics Laboratory) | 0.838428 | 3.476458 |
Using images from NASA’s Swift satellite, astronomers have measured the amount of water production from comet C/2013 A1.
In late May, NASA’s Swift satellite imaged comet Siding Spring, which will brush astonishingly close to Mars later this year. These optical and ultraviolet observations are the first to reveal how rapidly the comet is producing water and allow astronomers to better estimate its size.
“Comet Siding Spring is making its first passage through the inner solar system and is experiencing its first strong heating from the sun,” said lead researcher Dennis Bodewits, an astronomer at the University of Maryland College Park (UMCP). “These observations are part of a two-year-long Swift campaign to watch how the comet’s activity develops during its travels.”
“Fresh” comets like Siding Spring, which is formally known as C/2013 A1, contain some of the most ancient material scientists can study. The solid part of a comet, called its nucleus, is a clump of frozen gases mixed with dust and is often described as a “dirty snowball.” Comets cast off gas and dust whenever they venture near enough to the sun.
What powers this activity is the transformation of frozen material from solid ice to gas, a process called sublimation. As the comet approaches the sun and becomes heated, different gases stream from the nucleus, carrying with them large quantities of dust that reflect sunlight and brighten the comet. By about two and a half times Earth’s distance from the sun (2.5 astronomical units, or AU), the comet has warmed enough that water becomes the primary gas emitted by the nucleus.
Between May 27 and 29, Swift’s Ultraviolet/Optical Telescope (UVOT) captured a sequence of images as comet Siding Spring cruised through the constellation Eridanus at a distance of about 2.46 AU (229 million miles or 368 million km) from the sun. While the UVOT cannot detect water molecules directly, it can detect light emitted by fragments formed when ultraviolet sunlight breaks up water — specifically, hydrogen atoms and hydroxyl (OH) molecules.
“Based on our observations, we calculate that at the time of the observations the comet was producing about 2 billion billion billion water molecules, equivalent to about 13 gallons or 49 liters, each second,” said team member Tony Farnham, a senior research scientist at UMCP. At this rate, comet Siding Spring could fill an Olympic-size swimming pool in about 14 hours. Impressive as it sounds, though, this is relatively modest water emission compared to other comets Swift has observed.
Based on these measurements, the team concludes that the icy nucleus of comet Siding Spring is only about 2,300 feet (700 meters) across, placing it at the lower end of a size range estimated from earlier observations by other spacecraft.
The comet makes its closest approach to Mars on Oct. 19, passing just 86,000 miles (138,000 km) from the Red Planet — so close that gas and dust in the outermost reaches of the comet’s atmosphere, or coma, will interact with the atmosphere of Mars.
For comparison, the closest recorded Earth approach by a comet was by the now-defunct comet Lexell, which on July 1, 1770, swept to within 1.4 million miles (2.3 million km) or about six times farther than the moon. During its Mars flyby, comet Siding Spring will pass more than 16 times closer than this.
Scientists have established that the comet poses no danger to spacecraft now in orbit around Mars. These missions will be pressed into service as a provisional comet observation fleet to take advantage of this unprecedented opportunity.
The Swift observations are part of a larger study to investigate the activity and evolution of new comets, which show distinct brightening characteristics as they approach the sun not seen in other comets. Bodewits and his colleagues single out comets that can be observed by Swift at distances where water has not yet become the primary gas and repeatedly observe them as they course through the inner solar system. This systematic study will help astronomers better understand how comet activity changes with repeated solar heating.
Image: NASA/Swift/D. Bodewits (UMD), DSS | 0.836992 | 4.005497 |
This story was updated at 12:51 p.m. EDT.
A NASA spacecraft and its trusty rocket stage are drawing ever closer to the moon to intentionally crash to their doom Friday, all in the name of science.
The cosmic collisions are expected to kick up tons of moon dirt in giant debris plumes that will then be scanned for signs of water ice suspected to be buried beneath the floor of a permanently shadowed crater at the lunar south pole.
"Everybody is feeling very excited," said Victoria Friedensen, NASA's program executive for the LCROSS mission at the heart of the moon crash. "There is a great sense of anticipation."
NASA launched the LCROSS probe in June along with a powerful lunar orbiter that is currently circling the moon to determine whether water ice, which could be a vital resource for astronauts in the future, actually exists in the perpetual darkness of craters at the moon's south pole.
Since then, the $79 million LCROSS — short for Lunar Crater Observation Sensing Satellite — has made three long loops around the Earth while attached to an empty Centaur rocket stage, its first weapon in the upcoming lunar double whammy.
The two vehicles are due to separate late tonight and the first impact is set for 7:31 a.m. EDT (1131 GMT). That's when the 42-foot (13-meter) long Centaur rocket stage will plow into the crater Cabeus at the moon's south pole. NASA will start broadcasting the event live on NASA TV at 6:30 a.m. EDT (1030 GMT).
Seasoned amateur astronomers may be able to see the crash using 10 or 12-inch telescopes depending on their location, local weather and lighting conditions. [Click here to see how to watch the LCROSS moon crashes.]
The Centaur rocket stage weighs 5,216 pounds (2,366 kg), about as much as a sport utility vehicle, and will slam into the moon at about 5,600 mph (9,010 kph). Researchers believe the blast will create a debris plume about 12 miles (20 km) wide and send moon dirt soaring to heights of 6.2 miles (10 km), where it would be illuminated by the sun.
"It will kick up whatever is on the floor of the crater," LCROSS project manager Daniel Andrews has said. "That may very well include water ice."
But the first crash is only the prelude. Riding aboard the LCROSS spacecraft are nine different science instruments, including cameras that will beam live views of the impact back to NASA's mission operations center at the Ames Research Center in Moffett Field, Calif. Those tools will be used to scan the debris plume for evidence of water ice.
"We expect to see the crater getting closer and closer," Friedensen told SPACE.com.
The 1,664-pound (891-kg) LCROSS shepherding craft will follow its Centaur rocket stage down to make its own crash about four minutes after the initial lunar hit.
More than 20 observatories on Earth, as well as a host of amateur astronomers, museums and volunteers will be watching the two crashes to search for signs of any water ice in the debris clouds. The Hubble Space Telescope and other space-based observatories will also turn their camera eyes on the moon for the event.
"Our last day in flight promises to be the most challenging and the most rewarding for the project," LCROSS flight director Paul Tomkins wrote in his NASA blog today. "Our 112 days in orbit are focused entirely on the last four minutes, after the Centaur impacts our target crater and raises a plume of lunar material for the LCROSS Shepherding Spacecraft to observe for signs of water, but before the Shepherd also impacts the moon."
Unlike other spacecraft that have smacked the moon, like Japan's recent Kaguya probe, Europe's Smart-1 and NASA's Lunar Prospector, the LCROSS impactors will hit at a steep angle in order to get the biggest boom for their buck, mission managers said.
LCROSS has not had a completely smooth ride to the moon. An August glitch forced the spacecraft to use much of its propellant supply, but not enough to prevent its ultimate mission.
NASA also unexpectedly switched target craters last week, choosing the 60-mile (98-km) wide Cabeus over its nearby neighbor Cabeus A because data suggested the new target had a higher concentration of hydrogen — a signal for potential water ice.
Hunting moon water
Scientists already know that some small amount of water exists on the moon, but LCROSS is designed to seek out buried water ice at the lunar south pole — a region where the sun has never shined on some craters with permanent shadows.
NASA scientists say the areas may be the coldest places in the solar system, with temperatures reaching minus 400 degrees Fahrenheit (minus 240 Celsius) in the crater shadows. Finding usable amounts of water ice would be a boon for NASA's vision to send astronauts back to the moon by the mid-2020s.
But Friedensen said that it will take time before scientists know if any water is present in the debris plumes. A few hours after the two impacts, LCROSS scientists will hold a press conference, but will likely only be able to discuss how accurate the hits were, she added.
"We will not be able to talk about how much water is there, if it's water we find," she said. "The science team will need a couple of days, maybe even a couple of weeks to make sure."
The live stream of data from LCROSS will be recorded in triplicate — at the mission control center at Ames and two other sites — to make sure it is saved for posterity, Friedensen added.
Tompkins said that knowing LCROSS will soon meet its fate is a bit sad, even if it was already preordained for the cause of science.
"Well, we all knew it was going to happen. It was inevitable. It was the whole design of the mission," he wrote. "LCROSS was destined to end its wonderfully fantastic journey by intentionally crashing into a permanently shadowed crater at the south pole of the moon."
SPACE.com is providing full coverage of the LCROSS moon crash. Click here for a look at the mission and return to SPACE.com at 6:30 a.m. ET (1030 GMT) for live crash coverage. | 0.830351 | 3.09548 |
But there's one thing that space really isn't: loud. Without Earth's air molecules to help you hear, out there in space you'd be listening to a whole lot of silence.
Luckily, that didn't stop NASA from figuring out a way to produce sound in the soundlessness of space back in 2019 - by 'sonifying' the above image taken by the Hubble Space Telescope.
Yep, move over music, podcasts, or audio-books - the new thing to listen to is Hubble images.
The image NASA used for this project was taken by the Hubble's Advanced Camera for Surveys and Wide-Field Camera 3 back in August 2018.
The guys working with Hubble call the image a 'galactic treasure chest' because of the number of galaxies splattered across it.
"Each visible speck of a galaxy is home to countless stars," NASA explained about the image.
"A few stars closer to home shine brightly in the foreground, while a massive galaxy cluster nestles at the very centre of the image; an immense collection of maybe thousands of galaxies, all held together by the relentless force of gravity."
But as beautiful as this image already is, it just reached a new level, once transformed into a stunningly eerie musical composition.
The team that created the sonified image explains that the different locations and elements of the image produce different sounds.
Stars and compact galaxies are represented by short and clear sounds, while the spiralling galaxies emit more complex, longer notes.
"Time flows left to right, and the frequency of sound changes from bottom to top, ranging from 30 to 1,000 hertz," NASA explained in comments accompanying the video.
"Objects near the bottom of the image produce lower notes, while those near the top produce higher ones."
And although it might sound a little eerie at first, the 'sounds' of this picture create a rather beautiful melody, especially near the middle, when the sound reaches a galaxy cluster called RXC J0142.9+4438.
"The higher density of galaxies near the centre of the image," the team explained, "results in a swell of mid-range tones halfway through the video."
So there you have it: an entirely new way to enjoy the Universe.
A version of this article was first published in March 2019. | 0.835836 | 3.090134 |
Where black hole research goes next
A close-up of the core of the M87 galaxy with a black hole in its center. Photo: NASA/CXC/Villanova University/J. Neilsen
The astonishing first photo of a black hole, revealed Wednesday by the team behind the Event Horizon Telescope, opens up new avenues for researchers to probe more deeply into the inner workings of these extreme and fundamental aspects of our universe.
Why it matters: The major announcement that scientists have finally caught one on camera, so to speak, paves the way for the pursuit of new avenues in astrophysics that will probe the nature of gravity, scientists tell Axios. This work may reveal limits to Albert Einstein's theory of general relativity.
Details: One focus for scientists going forward will be trying to observe and understand the powerful jets of radiation and ultra high-speed particles that are ejected from near the black holes at close to the speed of light. It's thought that black holes are the source for some of the most energetic particles in the universe, known as cosmic rays.
Context: The photo, taken by the Event Horizon Telescope, shows the shadow of the Messier 87 (M87) galaxy's supermassive black hole surrounded by a ring of light near the object's event horizon — the point at which nothing, not even light, can escape the gravitational pull of the black hole.
- The ring consists of superheated gases known as plasma, which forms as a result of the black hole's immense gravitational field.
- The material headed toward Earth appears brighter than the side moving away.
What's next: Sera Markoff, a member of the EHT science council and theoretical physicist at the University of Amsterdam, tells Axios that even with the new discovery, scientists are still limited in their understanding of black holes.
"I’m very interested in this interface with theoretical physics, and what are black holes really?" Markoff tells Axios.
"We know that Einstein was right in a general sense, but we don’t actually understand why gravity works the way it does on a really microscopic level. How does it function? Gravity is not a force like the others … general relatively explains how it works, but it doesn’t answer the why."— Sera Markoff
Markoff says the jets that are "literally rooted in the black hole" could be used to figure out something fundamental about the nature of space-time. "So we’re not there yet, but there’s just so much that’s going to come out of this," she says.
The intrigue: "The most exciting thing we could possibly do would be to supplant Einstein, to find that in this extreme gravitational laboratory that there’s something a little new," Avery Broderick, an astrophysicist with the EHT team, said at the press conference.
- "The problem of quantum gravity remains unsolved with the current tools that we have. Black holes are one of the places to look for answers," Broderick said.
Where it stands: Currently, EHT consists of 9 radio telescopes at 7 sites, including those in Antarctica and Greenland.
- The EHT team is planning to add 2 more to the mix by 2020 and is putting together proposals for a space-based telescope to boost capability for probing the secrets of black holes. | 0.889885 | 3.867329 |
Size of Neptune compared with the Earth
Facts about Neptune
- It takes Neptune 164.8 Earth years to orbit the Sun. On 11 July 2011, Neptune completed its first full orbit since its discovery in 1846.
- Neptune was discovered by Jean Joseph Le Verrier. The planet was not known to ancient civilizations because it is not visible to the naked eye. The planet was initially called Le Verrier after its discoverer. This name, however, quickly was abandoned and the name Neptune was chosen instead.
- Neptune is the Roman God of the Sea. In Greek, Neptune is called Poseidon.
- Neptune has the second largest gravity of any planet in the solar system – second only to Jupiter.
- The orbit path of Neptune is approximately 30 astronomical units (AU) from the Sun. This means it is around 30 times the distance from the Earth to the Sun.
- The largest Neptunian moon, Triton, was discovered just 17 days after Neptune itself was discovered.
- Neptune has a storm similar the Great Red Spot on Jupiter. It is commonly known as the Great Dark Spot and is roughly the size of Earth.
- Neptune also has a second storm called the Small Dark Spot. This storm is around the same size as Earth’s moon.
- Neptune spins very quickly on its axis. The planets equatorial clouds take 18 hours to complete one rotation. The reason this happens is that Neptune does not have a solid body.
- Only one spacecraft, the Voyager 2, has flown past Neptune. It happened in 1989 and captured the first close-up images of the Neptunian system. It took 246 minutes – four hours and six minutes – for signals from Voyager 2 to reach back to Earth.
- The climate on Neptune is extremely active. In its upper atmosphere, large storms sweep across it and high-speed solar winds track around the planet at up to 1,340 km per second. The largest storm was the Great Dark Spot in 1989 which lasted for around five years.
- Like the other outer planets, Neptune possesses a ring system, though its rings are very faint. They are most likely made up of ice particles and grains of dust with a carbon-based substance coating them.
- Neptune has 14 known moons. The largest of these moons is Titan – a frozen world which spits out particles of nitrogen ice and dust from below its surface. It is believed that Titan was caught by the immense gravitational pull of Neptune and is regarded as one of the coldest worlds in our solar system.
- Neptune has an average surface temperature of -214°C – approximately -353°F.
More information and facts about Neptune
When scientific discoveries are made there is often a debate (sometimes heated) as to who deserves credit. The discovery of Neptune is one such example. Shortly after the discovery of the planet Uranus in 1781, scientists noticed that its orbit had significant fluctuations that were not expected. To solve this mystery, they proposed the existence of another planet whose gravitational field would account for such orbital variances.
In 1845, the English astronomer John Couch Adams completed his calculations as to the position of this unknown planet. Although he submitted his findings to the Royal Society (the leading English scientific organization), his work was met with little interest. However, a year later the French astronomer Jean Joseph Le Verrier made known his calculations that were strikingly similar to those of Adams. As a result of the two men’s independent estimates being so close, the scientific community took notice and began its search for the planet in the region of the sky Adams and Le Verrier had predicted. On September 23, 1846, the German astronomer Johann Gall observed the new planet near to where Adam’s calculations had forecasted and even closer to those of Le Verrier.
Le Verrier was initially given credit for the discovery. As a result, an international dispute arose, with one faction championing Adams and the other Le Verrier. This conflict, however, was not shared between the two men themselves. Eventually, the campaign for each side cooled, and both men were given credit.
Until the Voyager 2 spacecraft fly-by in 1989, little was known about Neptune. This mission provided new information about Neptune’s rings, number of moons, atmosphere and rotation. Additionally, Voyager 2 discovered significant features of the moon Triton. There are no official planetary missions scheduled to Neptune in the near future.
Neptune’s upper atmosphere is composed of 80% hydrogen (H2), 19% helium and trace amounts of methane. Similar to Uranus, the blue coloration of Neptune is due in part to its atmospheric methane, which absorbs light having a wavelength corresponding to red. Unlike Uranus, Neptune is a deeper blue, and, therefore, some other atmospheric component must be present in the Neptunian atmosphere that is not found in Uranus’ atmosphere.
Two significant weather patterns have been observed on Neptune. The first, seen during the Voyager 2 fly-by mission, are the Dark Spots. These are storms comparable to the Great Red Spot found on Jupiter. However, a difference between these storms is their duration. Whereas the Great Red Spot has lasted for centuries, the Dark Spots are much more shortly lived as is evident by their disappearance when Neptune was viewed by the Hubble Space Telescope just four years after the Voyager 2 fly-by.
The second of the two weather patterns observed by Voyager 2 is the swiftly moving white storm system, nicknamed Scooter. This type of storm system, which is much smaller than the Dark Spots, also appears to be short-lived.
As with the other gas giants, Neptune’s atmosphere is divided into latitudinal bands. The wind speed achieved in some of these bands is almost 600 m/s, the fastest known in the Solar System.
The interior of Neptune, similar to that of Uranus, is made of two layers: a core and mantle. The core is rocky and estimated to be 1.2 times as massive as the Earth. The mantle is an extremely hot and dense liquid composed of water, ammonia and methane. The mantle is between ten to fifteen times the mass of the Earth.
Although Neptune and Uranus share similar interiors, they are, however, quite distinct in one way. Whereas Uranus emits only about the same amount of heat that it receives from the Sun, Neptune emits nearly 2.61 times the amount of the sunlight it receives. To place this in perspective, the two planets’ surface temperatures are approximately equal, yet Neptune receives only 40% of the sunlight that Uranus does. Additionally, this large internal heat is also what powers the extreme winds found in the upper atmosphere.
Orbit & Rotation
With the discovery of Neptune, the size of the known Solar System increased by a factor of two. With an average orbital distance of 4.50 x 109 km, it takes sunlight almost four hours and forty minutes to reach Neptune. Moreover, this distance also means that a Neptunian year lasts about 165 Earth years!
Neptune’s orbital eccentricity of .0097 is second smallest behind that of Venus. This small eccentricity means that the orbit of Neptune is very close to being circular. Another way of looking at this is to compare Neptune’s perihelion of 4.46 x 109 km and its aphelion of 4.54 x 109 km and notice that this is a difference of less than two percent.
Like Jupiter and Saturn, Neptune rotates very quickly as compared to the terrestrial planets. With a rotational period of a little over 16 hours, Neptune has the third shortest day in the Solar System.
The axial tilt of Neptune is 28.3°, which is relatively close to the Earth’s 23.5°. What is amazing is that, even at such a far distance from the Sun, Neptune still experiences seasons (though more subtly) similar to those on Earth as a result of its axial tilt.
Currently, Neptune is known to have thirteen moons. Of these thirteen only one is large and spherical in shape. This moon, Triton, is believed to have originally been a dwarf planet captured by Neptune’s gravitational field, and, thus, not a natural satellite of the planet. Evidence for this theory comes from Triton’s retrograde orbit of Neptune; that is, Triton orbits in the opposite direction that Neptune rotates. With a recorded surface temperature of -235° C, Triton is the coldest known object in the Solar System.
Neptune has three major rings – Adams, Le Verrier and Galle. This ring system is much fainter than that of the other gas giants. In fact, some of the rings are so dim that it was believed at one time that they were incomplete. However, images from the Voyager 2 fly-bys show extremely faint rings. | 0.905573 | 3.389278 |
Link to our semi-technical analysis of this apparition.
by Jeffrey L. Hunt
Venus shines as a brilliant evening star during late 2019 and early 2020. The apparition (appearance) includes conjunctions with Jupiter and Saturn that occur within a month. Then Venus moves past Neptune and Uranus. The appearance includes a close conjunction with the Pleiades and a quasi-conjunction (near conjunction) with Beta Tauri. The apparition ends as Venus dives toward inferior conjunction and has a conjunction with Mercury, followed by a pretty grouping of the two planets, Beta Tauri, and the moon.
Click through the collection of Venus
The young lunar crescent’s appearance with Venus is always an exciting time to view and photograph the brilliant planet and the moon displaying Earthshine. The best view occurs on November 28, when the pair is 1.9° apart.
The chart above shows the setting time of Venus compared to sunset along with other bright stars near the ecliptic and the moon. The chart is constructed from data from the U.S. Naval Observatory for Chicago, Illinois. When the Venus line crosses the lines of other objects, they set at the same time. A conjunction occurs near the intersection. If a moon circle is near one of the setting lines, a conjunction may occur on that date, or on the day before or day after the date the moon and that object are plotted together.
It is important to note that because two objects set at the same time, they may not appear close together in the sky. Two objects that are far apart in the sky can set at the same time. Because objects have been selected for the chart that are near the ecliptic, close conjunctions might occur. While Antares, Aldebaran, and Pollux generally lie near the ecliptic, the conjunctions with planets usually have gaps of several degrees.
Venus passes superior conjunction at 1:07 a.m. CDT on August 14, 2019, nearly 1.3° north of the sun. Because of the time, the conjunction is invisible in the Central U.S., but Venus can be found with optical assistance in a clear sky northeast of the sun after it rises that morning. Great care must be taken for visual observations of the planet in close proximity to the sun
Venus Emerges Into Bright Evening Twilight
Venus climbs into bright evening twilight in the southwestern sky and is soon visible in darker skies. It is headed toward a conjunction with Jupiter in about a month. On October 27, Venus is 20° from the sun and sets in the southwest and about an hour after sunset.
In the charts that follow, several of them are displayed for a time interval after sunset. Use local sources for the time of your sunset. The U.S. Naval Observatory has an online calculator that displays a year of sunrises and sunsets. Enter your state and city into Form A on the website. Make appropriate changes for Daylight Saving Time. For readers outside the U.S., enter your longitude and latitude in Form B for your yearly table. Click here.
The moon makes its first appearance with Venus on October 29, as illustrated above. Thirty minutes after sunset, the moon appears to the upper left of Venus, only 4° up in the southwest with bright Jupiter to the upper left of the pair. The moon is 1.8 days old, past its New phase, and 4.4% illuminated. The moon appears with Jupiter two evenings later (October 31). By early November, Venus continues to set later. By November 4, it sets about an hour after sunset.
Venus – Jupiter Conjunction
For the second time during this apparition of Jupiter, Venus passes the Giant Planet. Watch Venus move into Ophiuchus and then it passes Jupiter on the edge of Sagittarius. The next conjunction is February 11, 2021, but the planets rise during bright morning twilight. On April 30, 2022, the planets rise into the eastern sky about 90 minutes before sunrise 29’ apart, an Epoch Conjunction. During the current apparition, Venus and the moon have a very nice pairing (1.9°) near the end of November. Follow the progress of the 2019 Venus – Jupiter conjunction during November:
On November 9, thirty minutes after sunset, Venus, nearly 6° up in the southwest, is 3.9° to the upper right of the star Antares. The Venus – Jupiter gap is 15°. Venus continues to set later, appearing higher at the same time each evening.
By November 13, thirty minutes after sunset, the Venus – Jupiter gap is over 10°. Venus is 6° up in the southwest. A few evenings later, November 16, Venus is 25° east of the sun. Thirty minutes after sunset, it is 7° in altitude in the southwest.
Venus continues to close in on Jupiter. By November 19, forty-five minutes after sunset, the Venus – Jupiter gap is about 5°. Venus is 4° up in the southwest. The separations until the conjunction: Nov 20, 3.9°; Nov 21, 2.8°; Nov 22, 2.1°; Nov 23, 1.5°, Venus is to the lower left of Jupiter.
On November 24, Venus is closest to Jupiter! Forty-five minutes after sunset, Venus, nearly 7° up in the southwest, is 1.4° to the lower left of bright Jupiter. This evening, Venus sets at its southern-most azimuth, 236°. It sets here until December 1. The Venus – Jupiter separations after conjunction: Nov 25, 2°, Venus is to the left of Jupiter; Nov 26, 2.8°; Nov 27, 3.7°, Venus is to the upper left of Jupiter; Nov 28, 4.7°.
On November 26, Venus sets at the end of twilight, over 90 minutes after sunset, when the sun is 18° below the horizon. Venus sets after the end of evening twilight until May 19, 2020.
The next evening, November 27, thirty minutes after sunset look for the crescent moon (1.3d, 2%), about 5° up in the southwest. It is nearly 11° to the lower right of Venus, with Jupiter between them, but Jupiter is closer to Venus.
On November 28, at mid-twilight (about 45 minutes after sunset) Venus and the moon (2.3d, 6.3%) have a classic appearance, with Venus 1.9° to the lower right of the moon. At this time, Venus is about 7° up in the southwest. Both appear in the viewfinder of a camera with a 300 mm focal length lens. A longer exposure reveals Earthshine on the moon.
Venus continues to move away from Jupiter. On November 30, Venus passes 0.8° to the upper right of Kaus Borealis, the star at the top of the lid of the Teapot of Sagittarius.
Venus – Saturn Conjunction
As Venus moves away from Jupiter, it approaches and passes Saturn. Watch Venus close the gap on Saturn and pass it on December 10. Venus passes Saturn again on February 6, 2021 in a difficult-to-see conjunction, just 5 days before the Venus-Jupiter conjunction of 2021. On the morning of March 29, 2022, Venus is 2.1° from Saturn. Mars is nearby, 4.4° to the upper right of Saturn.
- The diagram above on December 2, 45 minutes after sunset, shows Venus about 9° up in the southwest. It is about 10° to the lower right of Saturn. On the next evening, December 3, the three evening planets – Venus, Jupiter, and Saturn – are nearly equidistant tonight, but they are not along the same arc in the sky: Venus – Saturn, 8.6°; Venus – Jupiter, 9.7°.
Venus continues to move eastward compared to the starry background toward Saturn. On December 5, Venus passes 1.9° to the upper right of Sigma Sagittarii. Venus continues to close the gap on Saturn. Venus – Saturn separations until the conjunction: Dec 7, 4.3°, Dec 8, 3.3°; Dec 9, 2.4°.
Venus passes Saturn on December 10. At mid-twilight, Venus, over 11° up in the southwest, is 1.8° to the lower left of Saturn. Venus – Saturn gaps after the conjunction: Dec 11, 1.9°; Dec 12, 2.5°; Dec 13, 3.4°, Venus is to the upper left of Saturn; Dec 14, 4.4°, Dec 15, 5.4°. Venus continues eastward against the starry background, moving farther away from Saturn. on December 19, one hour after sunset, Venus, 12° up in the southwest, is nearly 10° to the upper left of Saturn. Venus moves into Capricornus.
By the end of 2019, the crescent moon rejoins Venus. One December 28, about an hour after sunset, Venus is about 15° up in the southwest. The moon (2.8d, 8%) is 2.4° below the planet.
Venus as an Evening Star in 2020
Venus begins the New Year among the dimmer stars of eastern Capricornus. Now setting abut 3 hours after the sun, watch Venus move eastward into Aquarius and toward a Neptune conjunction.
Venus continues moving eastward, appearing higher in the sky when it is completely dark. By January 27, Venus is 40° east of the sun. At the end of evening twilight, Venus, 18° up in the west-southwest, is 0.2° to the upper left of Neptune, nearly 7° above the crescent moon (3.1d, 9%) and 0.2° to the lower right of Phi Aquarii. A binocular or small telescope is needed to see Neptune.
On the next evening, January 28, at the end of evening twilight Venus, about 18° up in the west-southwest, is 7° below the moon (4.1d, 15%).
Venus Moves Into Pisces
During February brilliant Venus, still moving about 1.2° each day along the ecliptic, moves into Pisces and passes several dimmer stars. The starry background is dim.
By the end of February, the crescent moon is back in the evening sky. On February 26, at the end of twilight, the moon (3.4d, 10%), 14° up in the west, is 10° to the lower left of Venus. On the next evening, February 27, at the end of evening twilight, Venus, 25° up in the west, is nearly 7° to the right of the waxing crescent moon (4.4d, 16%)
Venus Moves Through Aries: A Venus – Uranus Conjunction
During March, Venus crosses into Aries, passing far from the constellation’s brighter stars. It is heading toward a conjunction with Uranus
Venus closes in on the planet Uranus. On March 7, Venus is 2.2° to the right of Uranus. The planet is brighter than Neptune, which Venus passed in January. In a dark sky, Uranus is visible in a dark sky to those with good eyesight. Use a binocular to see it easier.
Venus continues to set later in the evening and appears farther from the sun. On March 24, Venus is at greatest elongation (46.1°) at 5:13 p.m. CDT. We see Venus farthest from the sun during these evenings. At the end of evening twilight, Venus is over 25° up in the west.
As the weather warms in the northern hemisphere, Venus approaches the Pleiades star cluster. Here we reference the Pleiades with its brightest star Alcyone (Eta Tauri) The moon enters the region with Venus. On March 27, Venus is nearly 10° to the upper right of the waxing crescent moon (3.7d, 12%) and 6.5° to the lower right of the Pleiades. Here are the gaps as Venus closes in on the star cluster: March 30, 3.6°; March 31, 2.7°; April 1, 1.8°; April 2, 0.9°, Venus is below Alcyone.
On March 28, at the end of evening twilight, Venus, 26° up in the west, is 8° to the lower right of the moon (4.7d, 18%) and 5.5° to the lower right of the Pleiades. The trio – Venus, Moon, and Pleiades – makes nearly an equilateral triangle. Venus sets at its maximum interval after sunset – 4 hours, 7 minutes, through April 7.
Venus in Taurus: A Spectacular Pleiades Conjunction
In late March, Venus moves into Taurus, heading for a conjunction with the Pleiades. During April, Venus moves between the Pleiades and Hyades and toward Elnath (Beta Tauri, m = 1.6), the Bull’s northern horn. As Venus approaches the star, it begins a rapid descent toward the western horizon, toward its early June inferior conjunction.
On March 30, Venus moves into Taurus, 3.6° to the lower right of Alcyone, the brightest star in the Pleiades star cluster. The next evening, March 31, at the end of evening twilight, Venus, over 25° up in the west, is 2.7° to the lower right of Alcyone.
As April opens Venus is in the west near the Pleiades. On April 3, one hour after sunset, Venus, 30° up in the west, is 0.3° to the lower left of Alcyone. This is the closest Venus gets to the Pleiades on this evening appearance.
On the next evening, April 4, on this evening and for the next few evenings Venus and Sirius are at nearly the same altitude in the west at about 9 p.m. CDT in Chicago, a few minutes after the end of evening twilight (about 105 minutes after sunset). While Venus and Sirius are too far apart for technical comparisons of their brightness difference, the brightest star and the brightest planet are the same altitude in the western sky. Sirius, Orion’s belt, Aldebaran, and Venus are nearly in a line across the western horizon. The Venus – Alcyone gap, 0.9°. Gaps as Venus moves eastward along the ecliptic and away from the Pleiades: April 5, 1.8°; April 6, 2.7°; April 7, 3.5°; April 8, 4.6°; April 9, 5.2°.
Venus moves between the Pleiades and the Hyades. On April 9, at the end of evening twilight, Venus, nearly 25° up in the west-northwest, is below a line that extends from Aldebaran to Epsilon Tauri. Venus passes nearly nearly 7° to the upper right of Epsilon Tauri on April 12.
Venus continues to brighten from its first appearance in the evening sky. Beginning April 13, Venus reaches its maximum brightness until May 10. The midpoint, April 27, is marked on the setting chart (GB) near the beginning of the article. While the planet may grow brighter, as measured with detailed light measurements through a telescope, our eyes likely cannot perceive the minute difference in brightness during this duration. The planet reaches its latest setting time 11:33 p.m. CDT in Chicago, 243 minutes after sunset. This setting time continues until April 18.
Venus continues its climb through Taurus. On April 14, one hour after sunset, Venus, 30° up in the west, passes nearly 10° to the upper right of Aldebaran. A week later, April 21, Venus sets at its northern most setting azimuth (309°). It sets here until May 14.
As Venus continues through Taurus, it moves toward Beta Tauri, the northern horn of the Bull. On April 26, One hour after sunset, Venus, over 25° up in the west-northwest, is over 7° to the right of the crescent moon (4d, 14%). The planet is 5.5° to the lower right of Beta Tauri. The moon is 5° to the lower right of Zeta Tauri, the southern horn of Taurus.
Venus is at the interval of greatest brightness on April 27. On this evening, the waxing crescent moon (5.0d, 22%) is over 17° to the upper left of Venus. The planet has an elongation of 40°, and it is midway between its greatest elongation and inferior conjunction. Venus is at its greatest illuminated extent. The illuminated portion of the planet covers the largest area of the sky. (For a more technical explanation of greatest illuminated extent, see https://tinyurl.com/venus-greatest-illuminated.) Venus closes in on Beta Tauri. The gaps: Apr 27, 5.1°; Apr 28, 4.6°; Apr 29, 4.1°; Apr 30, 3.7°.
A Venus – Beta Tauri Quasi-Conjunction and a Venus – Mercury Conjunction
During May, Venus rapidly descends toward the western horizon, as measured from its setting time compared to the sun. Venus is nearing its quasi-conjunction (or near conjunction) with Beta Tauri. The gap between the brilliant planet and the star: May 1, 3.3°; May 2, 2.9°; May 3, 2.6°; May 4, 2.3°; May 5, 2.1°; May 6, 1.9°; May 7, 1.7°; May 8, 1.6°, May 9, 1.5°.
On May 10, Venus is at its closest approach to Beta Tauri, a quasi-conjunction or “near conjunction.” One hour after sunset, Venus, over 17° up in the west-northwest, is 1.4° to the lower left of the star.
The next evening, May 11, Venus is 30° east of the sun. The Venus – Beta Tauri gap is still 1.4°, but slightly larger than last night, when the small fractions of a degree are included in the measurement. The Venus – Beta Tauri gap begins to widen: May 12, 1.5°; May 13, 1.6°; May 14, 1.7°; May 15, 1.8°; May 16, 2.0°; May 17, 2.2°; May 18, 2.4°.
On May 19, Venus sets at the end of evening twilight, nearly 2 hours after sunset. Forty-five minutes after sunset, Venus, 11° up in the west northwest, is 2.7° from Beta Tauri. As this celestial pair descends toward the western horizon during the next several evenings, Mercury emerges from the sun’s glare for its evening apparition. This evening. Venus is 4.8° to the upper left of Mercury (m = −0.8). Watching Mercury’s rapid movement during the next several evenings, you will see it move from Venus’ lower right to its upper left.
Venus is moving very rapidly toward the sun. On May 20, Venus is 20° from the sun. The Venus – Beta Tauri gap is 3.0° and bright Mercury is 2.8° to the lower right of brilliant Venus. During the next few evenings, the Venus- Beta Tauri gap continues to widen: May 21, 3.4°; May 22, 3.8°.
Mercury closes in on Venus. On May 21, Venus, in the west-northwest, is 1.1° to the upper right of bright Mercury, a conjunction. The Venus – Beta Tauri gap is 3.4°.
On May 22, Venus, Mercury, and Beta Tauri make a compact triangle. Venus is 1.6° to the lower right of Mercury; Venus is 3.8° below Beta Tauri; and the Mercury – Beta Tauri gap is 3.4°. Tomorrow evening the moon enters the scene.
During the next evening, May 23, at 45 minutes after sunset, Venus, about 8° up in the west-northwest, is 4.7° to the upper right of the crescent moon (1.3d, 2%). The Venus – β Tauri gap is 4.2°. Mercury is 3.6° to the upper left of Venus and 3.1° to the lower left of Beta Tauri.
This spectacle is not, yet, finished. On May 24, Venus, bright Mercury , Moon (2.3d, 5%), and Beta Tauri are near each other. The planets and the star make a triangle. Mercury is 5.5° to the upper left of Venus, nearly midway from Venus to the moon that is nearly 12° to the upper left of Venus, although Mercury is above a line that connects Venus and the moon. Betai is 4.6° above Venus and 3.5° to the upper right of Mercury. Venus’ elongation from the sun is 15°.
The next evening, May 25, 45 minutes after sunset, Venus is 4° up in the west-northwest. The planet continues to make a triangle with Mercury and Beta Tauri. Venus is 5.1° to the lower right of the star, while Mercury is 4.5° to the upper left of Beta Tauri. Venus sets at Nautical Twilight, over an hour after sunset. The observing window is rapidly closing to see Venus. The gaps of the two planets and star continue to grow as Venus disappears into brighter twilight.
Venus is now quickly disappearing into bright twilight. On May 28, 30 minutes after sunset, Venus is less than 3° up in the west-northwest. The planet is only 9° from the sun, setting only 49 minutes after sunset.
By May 30, Venus sets at Civil Twilight, 32 minutes after sunset. Good-bye, Venus, for this appearance!
On June 3, Venus is at inferior conjunction, 12:44 p.m. CDT, when it is 0.5° north of the sun and 58” across.
This evening apparition of Venus has several exciting conjunctions with planets and stars. As with every evening appearance, Venus slowly moves into the sky. As the evening ecliptic takes a more favorable angle as the weather warms and daylight grows, the planet reaches its latest setting time and greatest brightness as Spring arrives. At this time, it has a spectacular conjunction with the Pleiades and a near-conjunction with Beta Tauri before it seemingly dives between our planet and the sun to reappear in the morning sky. Early during the next apparition, Venus has a double conjunction with Aldebaran and a traverse through the Hyades in a fairly dark sky. It also passes several bright stars near the ecliptic including Regulus and Spica. Appearances of Venus with the moon provide broader views of the sky. As noted in the daily descriptions, Venus has conjunctions with Saturn and Jupiter, but they occur during bright twilight. When the Venusian cycle repeats its motions in eight years, Venus goes into the Pleiades appearing nearly between Merope and Alcyone. | 0.83297 | 3.415282 |
THE BASIC FACTS :
Figure 1: This graph presents an overview of the architecture of binary systems harboring a confirmed exoplanet on an S-type orbit, that is, a planet orbiting one of the two stars in the system. This list is exhaustive for all binaries of separation <200 AU (A more complete list, with separations up to 500au can be found at the end of this page)
Detailed description: All systems with at least one confirmed exoplanet and one confirmed stellar companion (or with non-background probability of <1%) with projected separation <200au. The blue circles' location shows the semi-major axis of the exoplanet while the yellow circles show the location of the companion star. The radius of the blue circle is proportional to the estimated radius of the planet (or the cubic root of its mass when only a mass estimate is available). The radius of the yellow circle is proportional to the cubic root of the mass ratio between the companion and the central star (for the sake of visibility, the sizes of the planets have been inflated by a factor 20 with respect to the sizes of the yellow stars).
For both the planets and the stars, the horizontal purple line represents the radial excursion due to the object's eccentricity. Note that, for most stellar systems of separation > 30-50AU, the semi-major axis of the binary is unknown and the only available information is the projected separation between the stellar components. These cases are indicated by a "|" symbol overlaid onto the companion star.
The black vertical line plotted between the planet and the stellar companion represents the outer limit for long-term orbital stability as estimated with the widely used empirical formula of Holman & Wiegert (1999), assuming that the planet and the binary are coplanar. For systems where only the projected separation of the binary is known, the stability limit is computed assuming that the companion star is on a circular orbit whose radius is equal to the projected separation. // Planets detected by the radial velocity method are written in black, planets detected by transit are in blue, and planets detected by other methos are in red.
Figure originally in Thebault & Haghighipour (2015) (N.B. : The graphs might be freely re-used, as long as properly credited to Philippe Thebault and referring to the original Thebault & Haghighipour (2015) article)
Last major updates:
- 21/02/2020 (added HR858, HD42936 and DS Tuc)
- 27/01/2020 (new companions detected around WASP-systems by Bohn et al., 2020)
- 29/11/2019 (including all new data on stellar-companions to exoplanet-hosts derived (using Gaia data) by Mugrauer et al., 2019)
TRIPLE AND QUADRUPLE SYSTEMS:
Some of the presented cases are in fact higher-order multiple systems, mostly triple or even quadruple stellar systems. However, almost all of these systems are highly hierarchical, meaning that the third star does not significantly impact the dynamical evolution of the planet. This is why, for the sake of clarity and simplicity, we chose to present them as "binaries", labelling them with an additional "*" at the end of the system's name, with a brief explanation presenting the system's specificity. Most of these hierarchical cases fall into 2 categories:
1) Systems where either the central or the companion star is itself a very tight spectroscopic binary. In this case, the dynamical stability of the planet is computed by merging the two stars into one "effective" central or companion star
2) Systems where the third star is very distant from the central binary, typically more than 10 times the distance of the closer companion star. In this case, the gravitational pull of the third star is ignored when estimating the planet's stability.
OTHER SPECIAL CASES:
For most cases, the planet orbits the more massive component (usually labelled as "A") of the binary. In this case, we simply give the stellar name without adding the "A". For the few systems where the planet orbits the lower mass ("B") binary component, we specify it be adding the "B" at the end of the stellar name.
For a few systems (2 so far), there are planets orbiting each member of the binary. In this case, the system is divided into two "binaries", one where the first star is the "central star" and the other star is the perturbing companion, and another one where the roles are reversed.
We chose a rather conservative policy of excluding all systems with « planetary » objects having a mass (or a minimum mass) higher than 13 MJup. However, we display the > 13 MJup companions for the few systems (2 so far) for which an exoplanet has been detected in addition to them. These >13 MJup objects are drawn in orange instead of blue.
A FEW WORDS OF CAUTION:
As already pointed out, for the vast majority of systems where only the projected separation between the stars is known while the actual orbit of the binary remains unconstrained, we consider the fiducial configuration of a binary having a circular orbit equal to the projected separation. The estimated stability limit thus only gives a first-order estimate and should be taken with caution. However, it can be reasonably considered as a rather conservative assumption with respect to the planet's orbital stability, as it corresponds to the smallest possible physical separation between the stars.
On a related note, for most systems there is another unknown parameter, which is the relative inclination between the planetary and binary orbital planes. We have considered the simplest possible case of a coplanar configuration, which might hold for the tightest binaries, since observations of young binaries have shown that proptoplanetary discs tend to be aligned with stellar equatorial planes for separations up to 30-40AU (see Hale, 1994). But significant inclination values, possibly entailing complex effects such as the Kozai mechanism, cannot be ruled out for most systems. As a matter of fact, some detailed numerical studies have shown that large i values could increase the odds for long term orbital stability for some specific planets observed at the limit (or even beyond the limit) of the coplanar orbital stability (HD196885, HD59686).
Although it might be tempting to do so, it is difficult to straightforwardly derive statistics regarding the incidence of planets in binary systems, because the available list of systems is affected by several strong biases. The first one is that, until relatively recently, observational surveys, especially those relying on the radial velocity method, had been strongly biased against binaries, excluding known multiple systems from their potential targets. Another issue is that, for many cases, the binarity of the system was not known at the time of the exoplanet's discovery and was established by later observational campaigns. This means that there should still be a potentially large population of exoplanet-hosting "single" stars that are in fact members of a (yet undetected) multiple system. To alleviate this problem, several large-scale adaptive optics surveys are currently underway in order to assess the presence of stellar companions around exoplanet hosts. These surveys have already detected a large number of potential stellar companions (albeit mostly around yet-unconfirmed KOIs ("Kepler Object of Interest")), but the physical link between stellar components (as opposed to chance alignment with background stars) of each individual system remains yet to be established (see, for instance, Wang et al., 2015a,2015b, Kraus et al., 2016, or Ziegler et al., 2017).
NOTES ON SOME INDIVIDUAL SYSTEMS:
- Gamma Ceph A is a post-main-sequence star (sub-giant). Recent astrometry analysis (Benedict et al., 2018) shows that there is a 70 degrees mutual inclination between the binary and planetary orbits and that the planet probably has a much higher mass than previously expected (9 MJup).
- 30Ari B is actually part of a wide triple system (component Ari A, see Kane et al., 2015). What we show here is the BC binary. The orbit of the Ari C companion is poorly constrained: with a separation of 21.9AU, the constraint is that e<0.75. I took e=0.75/2 as a reference value. (And the component Ari Aa is actually also a very tight binary)
- Kepler 410 is maybe a triple system with a star "C" between A and B (Gajdos et al., 2017) / Binary revised by Mugrauer(2019)
- Kepler 420: The binary companion was inferred by Santerne et al.(2014) based on joint analysis of RV, bisector and FWHM variations. It should be confirmed by other independent constraints.
- Kepler 444: it is a triple star, so the data corresponds to the merged B+C M-stars (Dupuy et al., 2016).
- HD8673: The "planet" is at the brown dwarf limit. The projected separation is actually 11AU only. The given orbit is the closest stable one as computed by Roberts et al.(2015)
- HD87646: the 2nd "planet" is potentially a brown dwarf
- HD131399: DISCARDED. It is a hierarchical triple (the companion star is in fact a tight binary, see Wagner et al., 2016): Nielsen et al.(2017) discard the imaged planet as a being a background star
- HD106515: The binary orbit corresponds to that with lowest possible e and a, but there is a wide range of other possibilities (see Fig.9 of Desidera et al., 2012). Better (but still loose) constraints on the orbit given by Rica et al.(2017). Refined projected distance in Mugrauer(2019)
- Kepler 132 possesses at least 3 planets, and we know that 2 of them (b and c) cannot orbit the same star. But we don't know which planet orbits which star. There is also a 4th planet that is still a KOI. (Lissauer, et al., 2014, Everett et al., 2015)
- HD132563B: The distant A component is itself a binary of separation 15AU (Desidera et al., 2011)
- Gliese667: Triple System. The planet-hosting C star is linked to the A-B binary at a projected distance of 230AU. The AB binary has an orbit with a =12.6AU and e=0.58. The stability has been calculated for a merged AB component
- Kelt 4: Kelt-4A is orbited, at a projected separation of 328AU, by a binary (B-C), composed of 2 identical K stars separated by 10.3AU. The stability has been calculated for a merged BC component (Eastman et al., 2015)
- HD65216: The B component is in fact a B-C tight binary of separation 6AU (Mugrauer et aL, 2007)
- Kepler 21, 68 , HD197037, HD217786: binarity discovered by Ginski et al.(2016)
- HD28254: listed as binary in Moutou et al. and Lodieu et al.(2014).
- HD30856, HD116029, HD207382, HD86081, HD43691. All objects described in Ngo et al.(2017). HD30856, 86051, 207382: companions presented for the first time in this paper. HD43691 & 116029: companions confirmed by Ngo.
-Kepler693: 150Mjup companion inferred by Masuda by modelling the transit timing&duration variations. Planet and Binary planes should have a mutual inclination of 53 deg.
-Kepler13: the B component is in fact a binary (separation 0.410UA)
-HD126614 is a triple star, the third component is beyond 1000AU (Gould and Chamané, 2004)
-HD2638 is a triple star. The planet is actually orbiting HD2628B, the companion being HD2638C. But there is a third, more massive star (called HD2567, not HD2638A) at a projected separation of 839" (45000AU, see Roberts et al., 2015)
-TauBootis: refined investigation of the binary by Justesen&Albrecht(2019). Finds a larger semi-major axis than before (221 instead of 118, but with a large uncertainty). And constrains q to 28.3au+-3. Planetary and Binary orbits should be aligned.
- LTT 1445: Triple system with 3 M stars. The A component is orbited by the BC pair, whose orbit has been constrained to be a=8,00au and e=0.5 (Winters et al., 2019). The A-BC orbit is unconstrained.
- HD202772: first hot-Jupiter discovered by TESS. The A star is mildly evolved. The bound nature of the AB pair has been confirmed by Mugrauer(2019).
- HD4732: Planets by Sato et al.(2013)
- HD19994: also known as 94 Cet / planet by Queloz2001 / binary parameters by Hale1994, revised by Roberts(2011) / B is itself a compact binary (BC) (Röll et al.2011)/ proj.separation (50au) by Mugrauer2019. This system is highly inclined with respect to the line of sight (104degres), with a « real » orbit of a=220 & e=0.26 (Roberts2011).
- WASP-49: Planet by Lendl(2012) / Binary in Mugrauer(2019)
- omi Uma: Planet by Sato(2012)/ Binary in Mugrauer2019
- HD93385: planets by Harris2012 / Binary in Mugrauer2019
- HD98736: planet by Ment(2018) / binary in Vogt(2015)
- HD102365: planet by Tinney(2011) / Binary well known
- HD103774: Planet by Lo Curto(2013) / Binary identified by Mugrauer(2019)
- HD108341: Planet by Moutou(2014) / binary in Mugrauer2019
- Qatar 6 : Planet by Alsubai(2018) / Binary by Mugrauer(2019)
- HD133131: each star of this wide binary possesses planets (Teske, 2016).
- HD142245: Planet by Johnson(2011)/ Binary and binarity of the BC component in Mugrauer2015
- Kepler1651: Planet by Fischer(2012)/ Binary by Mann(2017), revised by Mugrauer(2019)
- HD176051: Planet detected by astrometry by Muterspaugh(2010) / Not sure which star the planet is orbiting (I’ve put A by default) / binary well known, orbit by Muterspaugh(2010)
- Kepler1319: Planet by Morton(2016) / binary by Mann(2017), revised by Mugrauer(2019) / not sure around which star the planet is orbiting
- Kepler333: Planets by Rowe(2014) / Binary in Mugrauer(2019)
- HD185269: Planet by Moutou(2006)/ The B component is itself a tight binary (BC)
- WASP145: Planet by Hellier(2018) / Bound nature of the AB pair confirmed by Mugrauer(2019)
- HD220842: Planet by Hebrard(2016 / Binary by Mugrauer(2019)
- WASP-8: Triple system, with a distant (14500au) C component / Planet b in transit by Queloz(2010), Planet c in RV by Knutson(2014)
- HD114762: DISCARDED: The study by Kiefer et al.(2019) shows that the « planetary » companion has a mass of more than 100 MJup.
- WASP-108: triple system: wide companion (>2000au) detected by Evans(2018), closer companion by Bohn(2020). Possibly a 4th object at 5" (Bohn2020)
- HD42936: planet and binary by Barnes(2019)
- HR858: planets by Vanderburg(2019). Mass of HR858B not given, extrapolated from its radius
- DS Tuc: Planet and binary by Newton(2019) / Young (40Myr) system in the Tucana-Horologium association
Online catalogue giving additional data about planets in binaries:
- Catalogue of exoplanets in binary star systems
Review paper on planet formation in binaries:
- Thebault & Haghighipour, 2015
Page developed and maintained by Philippe Thebault
Figure 2: Same as Figure 1, but with all exoplanet-hosting binaries with separations up to 500au: | 0.892729 | 3.963923 |
Light escaping from a black hole may “boomerang” its way to freedom, new X-ray images reveal.
Researchers found this odd behavior while reviewing archival X-ray observations of a black hole that’s approximately 10 times as massive as our sun. Located about 17,000 light-years from Earth, the black hole siphons material from a partner star; together, the black hole and star are known as XTE J1550-564.
Things can get pretty weird around a black hole. These exceptionally dense cosmic objects exert such a powerful gravitational pull that even light can’t resist their attraction. And scientists recently found that light behaves even more strangely around a black hole than once thought. Light in a black hole’s accretion disk — a spiraling, flattened cloud of dust and gas that circles the edges of a black hole — can sometimes escape into space. But the departing light from the XTE J1550-564 black hole didn’t follow the predictable path. Instead of escaping directly from the disk, the light was instead pulled back toward the black hole and then reflected off the disk and away from the black hole “like a boomerang,” researchers reported in a new study.
They modeled the black hole’s accretion disk and its corona — a lower-density gas zone very close to the black hole — using data captured by the Rossi X-ray Timing Explorer, a now-defunct NASA satellite mission that investigated black holes, neutron stars and other X-ray emitting objects between 1995 and 2012.
“Typically, what we study is light that comes from that gas” — the corona — “and it bounces off of this disk that’s spiraling toward the black hole,” said lead study author Riley Connors, a postdoctoral researcher in physics at the California Institute of Technology’s Cahill Center for Astronomy and Astrophysics in Pasadena, California.
Normally, the team studies light “coming from that corona and hitting the disk, bouncing off, and then arriving at our telescopes. That’s something we’ve been studying for a long time,” Connors told Live Science.
This time, however, some of the light bouncing off the black hole’s disk appeared to originate in the disk itself rather than in the corona; it was then dragged back toward the black hole before bouncing away.
“The thing that we found, that was predicted in the 1970s, is that you could see light that comes from the disk bent all the way back onto itself,” Connors said.
Light from different regions around the black hole has distinctive X-ray signatures that tell scientists where the light came from. When the study authors looked at the data for XTE J1550-564, they saw light that was reflected from the black hole but had emission “fingerprints” that didn’t quite match those in light that came from the corona, Connors said. The researchers then turned to computer models to explain the anomaly.
Putting a new spin on black holes
This discovery could help scientists confirm other elusive aspects of black holes, such as how fast they spin. Researchers already understand how an accretion disk around a black hole behaves. By adding this boomeranging light to their computer models, astrophysicists can then calculate a black hole’s rotation speed based on how much of the light is bending and bouncing back, Connors explained.
“It’s perhaps a more reliable way for us to measure how fast the black holes are spinning,” he said. ‘”
Though this phenomenon has been documented to date only in the XTE J1550-564 system, this is likely not the only black hole where light performs these unusual gymnastic feats, Connors said.
“We’re starting to look at data from other black holes; we have data from multiple X-ray satellites for dozens of these systems in our own galaxy,” he said. “We think that we should see this in many other sources.”
The findings were published online March 20 in The Astrophysical Journal. | 0.893484 | 3.939974 |
This set of Cassini spacecraft images shows a close-up view of two propeller structures in Saturn's A ring. These images are part of a large view (See Propeller Belt) that captures eight new propeller-like features in what may be the propeller "hot zone" of Saturn's rings.
Propellers were first discovered in Cassini images taken during Saturn orbit insertion in 2004. Propellers form around small moonlets that are not massive enough to clear out ring material, but are still able to push the ring particles into a shape reminiscent of an airplane propeller.
These pictures show two new propellers close up (one centered on each image). These images were put together from images in the Planetary Data System, a web site which archives and distributes scientific data from NASA planetary missions. The image on the top shows a propeller induced by a 150-meter (490-foot) moonlet (See Propeller Belt for a global view; with this close up marked with a red box). Smaller bright spots in the image are artifacts. The image on the bottom shows another propeller located just outside of the Encke Gap. Fine horizontal stripes seen in the image are wakes induced by the moon Pan.
In the top clear-filter image, taken during a stellar occultation on Aug. 20, 2005, the Cassini spacecraft narrow-angle camera observed the unlit side of the rings, with a phase angle of 126 degrees. The images were taken at 1 minute intervals with 0.05 seconds exposure time. Image resolution is 1 kilometer (0.6 miles) per pixel. The bottom clear-filter image was taken few hours later with 2 seconds exposure time. Image resolution is 1.5 kilometer (1 mile) per pixel.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, 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 was designed, developed and assembled at JPL.
For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov .
Credit: NASA/JPL/Space Science Institute/University of Colorado | 0.814634 | 3.02878 |
First Herschel SPIRE images outPosted: July 10, 2009
[tweetmeme only_single=false service=”wp.me” source=”allinthegutter”]
A couple of weeks ago ESA released the first images from the PACS instrument onboard the Herschel Space Telescope. This morning it followed them up with the equally impressive first light images from the longer wavelength, UK led, SPIRE instrument.
The images above show two spiral galaxies, M66 and M74. The wavelengths at which SPIRE operates means that it sees the glow from cold clouds of dust which occur in regions where lots of star formation is occurring (this is why the spiral arms show up so clearly). Even more interesting for me though are all the blobs that can be seen in the background to the images – each one is actually a much more distant galaxy, too far away from us to be seen as anything other than a point source. As the speed of light is always the same, looking at these galaxies is like looking back in time; the light Herschel has detected was emitted many, many years ago and has been travelling towards us ever since. This means that studying these objects can tell us about what things were like in the Universe when it was young.
This picture compares two images of the same nearby spiral galaxy, M74, one taken with the Spitzer Space Telescope and the other taken with the SPIRE instrument. It illustrates how much more detail Hershchel can see with its larger (3.5 m) mirror and more sensitive detectors.
More images from these first observations can be found here and see here for the UK Herschel Outreach Site which gives a good overview of the mission, including a fun counter showing how far away the satellite currently is along with how fast its now moving.
The quality of these images is amazing given that they were taken before the telescope’s been properly set up. I think it’s like buying a new TV, turning it on for the first time, and being able to start watching it after only half tuning it in. It’s all very exciting! | 0.832176 | 3.306652 |
Water is crucial for life, but how do you make water? Cooking up some H2O takes more than mixing hydrogen and oxygen. It requires the special conditions found deep within frigid molecular clouds, where dust shields against destructive ultraviolet light and aids chemical reactions. NASA’s James Webb Space Telescope will peer into these cosmic reservoirs to gain new insights into the origin and evolution of water and other key building blocks for habitable planets.
A molecular cloud is an interstellar cloud of dust, gas, and a variety of molecules ranging from molecular hydrogen (H2) to complex, carbon-containing organics. Molecular clouds hold most of the water in the universe, and serve as nurseries for newborn stars and their planets.
Within these clouds, on the surfaces of tiny dust grains, hydrogen atoms link with oxygen to form water. Carbon joins with hydrogen to make methane. Nitrogen bonds with hydrogen to create ammonia. All of these molecules stick to the surface of dust specks, accumulating icy layers over millions of years. The result is a vast collection of “snowflakes” that are swept up by infant planets, delivering materials needed for life as we know it. "If we can understand the chemical complexity of these ices in the molecular cloud, and how they evolve during the formation of a star and its planets, then we can assess whether the building blocks of life should exist in every star system," said Melissa McClure of the Universiteit van Amsterdam, the principal investigator on a research project to investigate cosmic ices.
In order to understand these processes, one of Webb’s Director’s Discretionary Early Release Science projects will examine a nearby star-forming region to determine which ices are present where. “We plan to use a variety of Webb’s instrument modes and capabilities, not only to investigate this one region, but also to learn how best to study cosmic ices with Webb,” said Klaus Pontoppidan of the Space Telescope Science Institute (STScI), an investigator on McClure’s project. This project will take advantage of Webb’s high-resolution spectrographs to get the most sensitive and precise observations at wavelengths that specifically measure ices. Webb’s spectrographs, NIRSpec and MIRI, will provide up to five times better precision that any previous space telescope at near- and mid-infrared wavelengths.
Infant stars and comet cradles
The team, led by McClure and co-principal investigators Adwin Boogert (University of Hawaii) and Harold Linnartz (Universiteit Leiden), plans to target the Chamaeleon Complex, a star-forming region visible in the southern sky. It’s located about 500 light-years from Earth and contains several hundred protostars, the oldest of which are about 1 million years old. “This region has a bit of everything we’re looking for,” said Pontoppidan.
The team will use Webb’s sensitive infrared detectors to observe stars behind the molecular cloud. As light from those faint, background stars passes through the cloud, ices in the cloud will absorb some of the light. By observing many background stars spread across the sky, astronomers can map ices within the cloud’s entire expanse and locate where different ices form. They will also target individual protostars within the cloud itself to learn how ultraviolet light from these nascent stars promotes the creation of more complex molecules.
Astronomers also will examine the birthplaces of planets, rotating disks of gas and dust known as protoplanetary disks that surround newly formed stars. They will be able to measure the amounts and relative abundances of ices as close as 5 billion miles from the infant star, which is about the orbital distance of Pluto in our solar system.
“Comets have been described as dusty snowballs. At least some of the water in Earth’s oceans likely was delivered by the impacts of comets early in our solar system’s history. We’ll be looking at the places where comets form around other stars,” explained Pontoppidan.
In order to understand Webb’s observations, scientists will need to conduct experiments on Earth. Webb’s spectrographs will spread incoming infrared light into a rainbow spectrum. Different molecules absorb light at certain wavelengths, or colors, resulting in dark spectral lines. Laboratories can measure a variety of substances to create a database of molecular “fingerprints.” When astronomers see those fingerprints in a spectrum from Webb, they can then identify the molecule or family of molecules that created the absorption lines.
“Laboratory studies will help address two key questions. The first is what molecules are present. But just as important, we’ll look at how the ices got there. How did they form? What we find with Webb will help inform our models and allow us to understand the mechanisms for ice formation at very low temperatures,” explained Karin Öberg of the Harvard-Smithsonian Center for Astrophysics, an investigator on the project.
“It will take years to fully mine the data that comes out of Webb,” Öberg added.
The James Webb Space Telescope will be the world’s premier infrared space observatory of the next decade. Webb will help humanity solve the mysteries of our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international project led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency). | 0.903439 | 4.031424 |
by Andrew Hall
The face of the Earth was shaped by three primary means: volcanic eruption, lightning, and wind. It occurred in primordial storms which significantly ionized the atmosphere, charged the ground like a battery, and discharged energy between them in the same way we see today: earthquakes, volcanoes and storms. Only these storms were beyond biblical. They occurred before Man arrived. These were the storms of creation, which shaped the face of the planet.
Because wind played the predominant role in laying and piling the sediments that most of us now live on, its effects are most visible to us. Once you start recognizing the characteristics of wind-formed topography, it becomes impossible to ignore.
To identify wind direction, look at mountains. Mountains (not volcanoes) are all essentially wind blown dunes. One side will be windward and one side will be leeward to the wind that formed them, and like a dune, reflects this in their shape. The leeward side is generally steep and slab sided, and the windward side dips at shallower slope.
The windward side actually portrays the shape of the wind itself, as pressure waves undulate across movable sands and mold them. The interface between wind and sand is created by the motions of the wind.
If the wind reaches Mach speed, standing shock waves reflect from any protrusion in the wind’s path and cause a sharp crease in the wind direction. Distinct patterns form at this crease where the wind direction changes abruptly. The reflected standing shock wave forms a fan-shaped interference pattern of compression and rarefaction. This pattern can be found on most mountain forms, including Cordillera mountain arcs, continental divides, lone inselbergs, and ‘island in the sky’ basin and range mountain structures.
Dust laden supersonic winds deposit their heavy cargo where the crease in the wind forms. A tetrahedron-shaped zone of rarefaction (low pressure) develops at the root of the standing wave, called a “separation bubble.” Wind-born dust collects in this bubble as the wind deflects upward with the shock wave.
As material deposits in the separation bubble, it forms a new barrier to deflect the wind, which moves the standing shock reflection backwards into the wind. The separation bubble migrates into the wind with the shock wave, causing new dust to overlay the old in layers that stack into the direction of the wind.
The shock wave is a discontinuity in density, temperature, and ionization. Remember, we are talking about a primordial storm where much of the atmosphere ionized. So, standing shock waves formed hot plasma sheets of electric current through the air. The separation bubble is not only a pressure sink, which collects heavy matter, but is also a current sink, being the lowest potential region connected to the high potential current in the reflected shock wave. It, therefore, draws current to bake, compress, and fuse the deposited dust.
It creates a distinct pattern on the windward side. Dragon’s teeth – triangular buttresses, sometimes called flat-irons, are formed by the sonic, ionized shock waves of supersonic winds. They rise and fall in amplitude and wavelength, and display harmonic frequency shifts, as well as many, many other features which could only be produced by the sonic effects of supersonic winds — see the “Arc Blast” and “Monocline” articles for more detail.
The behavior of shock waves, in particular the triangular shock patterns of compression and rarefaction they produce, is embossed on the land. It is also recorded in many ancient human artifacts, as we’ll discuss another time.
The Mexican Kink
Understanding how winds form these shock patterns and examining the result on the landscape reveals a wealth of information. Let’s consider this very simple dune, called El Guaje, in the Sierra Oriental mountains of central Mexico. The shock pattern of triangular buttresses is very apparent on its windward side.
The next annotated image of El Guaje highlights four consecutively formed pressure ridges that are visible. The first (green) is almost buried by later deposition and only the tops of its buttresses are exposed. The second (yellow) is a minor ridge caused by a period of weaker winds. It is also partially buried by the third, and largest ridge (red).
Large triangular buttresses at one end of the large (red) ridge shrink in amplitude with geometric progression until they almost vanish, indicating the jet-stream velocity transitioned from supersonic to near subsonic velocity along the wind-front of this dune. The faster jet-stream region advanced the growth of the dune, depositing material faster and pushing the shock-wave into the wind. It advanced the ridge line into the wind (violet) and built this portion of the mountain thicker, taller, with large amplitude reflected shocks forming bigger buttresses.
Each layer of the buttresses is formed by a new shock front from winds impinging on the last layer. New shock fronts formed as the winds gusted, piling new layers on the old. A final diminishing wind created a fourth shock front which deposited a small pressure ridge (purple) along the foot of the mountain. The highlights obscure natural features so please contrast all annotated images with the first, naked image.
The winds that created these ridges were like any storm, just quite a bit more violent. They stiffened as the storm grew, reached a crescendo with electrically charged, gusting blasts at Mach speeds, and then ebbed away. Their formation precludes any notion that the winds that created them were caused by meteor or comet. A large impact might produce supersonic, dust laden winds, but they would crest with the first shock wave and then dissipate, not slowly build to a crescendo.
Take a look at the surroundings of El Guaje ridge, and it becomes even more apparent how it was made. It is part of a larger structure — an oblong crater, two hundred feet deeper in the center than outside the rim. The pressure ridges, including El Guaje, form the rim of the crater.
It wasn’t made by an oblong meteor. This is the result of a down-burst wind. The pressure ridges are the rims of the crater, with triangular buttresses showing the wind direction as it blasted the Earth and blew out radially, depositing dust along the standing shock waves it created. The outward blast is interfered at the top end by two, round mountains formed by lightning discharge (or intense plasma filaments) that altered the wind flow around them.
Taking another step back reveals this entire mountain region in Mexico is shaped by a turbulent shear zone in the wind that was feeding the big storm over the Colorado Plateau. These mountains were formed by the uni-polar winds, screaming from the south, and mixing into plasma storms along the shear zone with opposite polarity uni-polar winds screaming the other direction. It is eerily similar to the turbulent shear zones adjacent to the Great Red Spot on Jupiter, creating kinked circulations that have a crab-claw shape.
Turbulent winds fold back and forth to make these kinks, but they also fold up and down and twist into tornadoes, blowing and sucking at the land. In turbulent zones, the downdrafts form cyclones that are often stretched out-of-round into oval, polygonal, and U-shaped structures. The winds are electric currents so these turbulent kinks are semi-steady-state and keep their form for a long time, molding the land.
Downdraft turbulence also means updraft turbulence. So next to downdraft craters in Mexico are mountains formed by updrafts. Updraft wind will create a dome or ridge of layered deposit with a rim around it also, but the inflow to the updraft leaves triangular buttresses from shock waves on the outside of the mountain, pointing inward.
The updrafts deposit linear and lobe shaped mountains around and between the downdraft craters. The turbulence is in a shear zone so deposits occur in narrow lanes between conflicting winds. Updraft deposits are composed of more material than craters and have the triangular patterns of shock wave reflections on the flanks.
As it relates to clouds on Jupiter, a long, rising column like the one highlighted below would create such linear mountains. One can see the dark depths of the hole in the clouds from which the updraft column rises. The winds roll upward from the ground and curl over, leaving a broom-swept linear ridge on the land below.
And, of course, the juxtaposition of the updraft and downdraft features must also be considered.
Also, the turbulent kinks in an electric circuit are fractal, so taking another step back reveals the fractal crab-claw shape emerging at a larger scale. The smaller feature with the crater shown above is nested within this larger repetition of the wind pattern shown next, aligned along the same axis. Nested fractals are very evident in Jupiter’s clouds as well.
The similarity between Mexico’s mountains and Jupiter’s clouds is due to capacitance in the planetary circuits. The strongest winds are rotating vertical winds created by the flow of electric currents. A few more examples using landforms from around the world will demonstrate this isn’t a freak local geology.
Following is a random sample taken from the southern leg of storm centers that molded South America, Australia, Africa, and Eurasia. The winds pushed and pulled on the land with electric force, literally molding it from wind action above and volcanic action below.
The fluid shapes are a dead giveaway for atmospheric electro-hydro-dynamic forces. But deeper levels of evidence are there, in Mach speed sonic shock effects, arcing effects, and sputtering effects that provide a holistic electric picture of everything that happened. Look close at the following images and note patterns of stratification and liquid deformation evident from waves of heat and pressure.
Turbulent winds lifting off the land, arcing across the sky, and returning in downdrafts were plasma currents — filaments of current that varied in charge density in cross-section. Take note how a tornado’s wind speed and density varies in cross-section with the outer wall of the tube being the fastest, most dusty region, and the inner core often a clear updraft. The plasma filaments of primordial storms varied in dust content, charge density, and velocity in cross-section as well.
The result is stratification of mineral deposits vertically, where rock morphology and mineral composition discretely change from the core of the feature, to the walls of the feature and then to the outer surroundings.
The following images show where the storm pulsed and ebbed with current, stratifying layers of dust with different dielectric composition from inside-out, where vertical up-and-down draft winds created domes and craters.
Layers of varying mineral composition are particularly evident where winds abruptly changed direction, from horizontal to vertical at the rim of craters and the buttressed flanks of mountains. There, charge densities in the shock waves and the effects of magnetic pinch were greatest.
The stratification of species within the electric winds of Jupiter matches the pattern of stratification in land forms. Each up- and down-draft swirl in the clouds is layered in colors of various mixtures of vapors and dust. They are coherently layered from the inside-out of each turbulent kink, or vortex, unmixed by the turbulence, in accordance with charge densities in currents primarily moving up and down.
That electromagnetic fields sort species and recombine them is predicted behavior in plasma. We use a multitude of techniques in manufacturing based on this fact. But the electrical properties of materials is not well understood. There are new findings every day about quantum fluids, superconductivity, and the behavior of materials in phase changes. There are new material properties being discovered, like “quantum atmosphere,” the “fourth phase of water,” and materials that are surface conductive yet insulators inside. The new discoveries all have to do with electricity.
Eighty percent of Earth’s surface rock is silica. Almost any rock you pick up is mostly silica, bound with oxygen and other constituents. Each constituent, how it is bound, its percentage in the rock and local concentrations, even how large the rock is, all affect the electrical properties. Silica, oxygen, trace minerals: it’s the formula we use to produce computer chips, and the Earth’s crust is essentially made the same way.
Different materials respond to magnetic fields differently. The electric field responds to charge density so shapes itself around conductive flows of material, and vice-versa. The result is stratification, and it’s apparent the stratification on Earth’s landscapes is a match for the stratification in Jupiter’s winds.
Some mountains do not conform to the wind-blown dune shape, exhibiting triangular buttresses on both flanks of the mountain, or not conforming to the windward/leeward angle of slope. This does not mean they are not dunes, but indicates they were formed subject to shifting, or competing winds.
In some cases, mountains formed as sastrugi, or linear deposits in the shear zone between laminated channels of wind of different velocity. In most cases, it is easy to distinguish the predominate ambient wind direction from the mountain flank with the most pronounced triangular buttresses, and of course, the obvious curve on the landscape.
So, it is possible by looking at the land to deduce wind patterns. Following this method, the next image shows the Colorado Plateau region with a significant number of wind formed pressure ridges annotated by blue lines. These are pressure ridges formed perpendicular to the wind. Each line is drawn parallel to the pressure ridge, and perpendicular hash marks indicate wind direction, pointing to where triangular buttresses formed. Red lines indicate sastrugi, or pressure ridges formed parallel to the wind, at the shear zone between conflicting winds.
Not every ridge line is annotated, and there is great complexity in the detail. A significant sampling of wind formed dunes in the most affected regions is presented to show large scale wind patterns generated by the storms.
These wind-blown pressure ridges show the direction of ground level winds entering and circulating in a complex fractal multi-vortex. This provides one layer of dimension to the storm. To add another layer, we can look at the signatures of updraft and downdraft winds. The North America map is rotated 90 degrees for better perspective.
Red areas are updrafts, yellow are downdrafts, blue are precipitation footprints. There are more than can be shown without making an indecipherable collage of color, because storm(s) progressed over time and there are layers upon layers. This is a best estimate of the last layer.
Mapping the most obvious downdraft craters and updraft domes and adding this layer of information to the pressure ridges, produces a wind map of the Colorado Plateau and Rocky Mountains that looks like this:
Two jet streams flowed from the north. One rose into a tight plasma mesocyclone forming Sacajewea Peak, which downdrafted through the Snake River Valley, arcing east towards Yellowstone. Yellowstone itself was erupting, creating its own rising mesocyclone. The downdraft from this storm made a dish-like crater next to it. These storms rained rock and ash from a multitude of volcanic eruptions from all along the ring of fire and Yellowstone.
The other northern jet stream swept into the largest mesocyclone in the system, rippling the great basin with rows of windblown dunes. An “S” shaped range of mountains in central Nevada defines the center of rotation, as this meso-cyclone scraped the ground as one incredible tornado. It down-drafted in two streams. One pressing down the Uinta Valley, Utah, the other sweeping northern Arizona and depositing much of the Mogollon Rim.
The Northern jet streams were wet and carried a tsunami of water, which will be discussed in future articles. Much of this water rained from the second jet stream as it rotated in the giant Great Basin tornado, leaving salt lakes between the rows of mountain range that, except for the Great Salt Lake, are now mostly dry.
The Great Basin tornado also spun air south, bypassing the rotation to help define the Sierra Mountain arc, and scoured deep valleys between tall linear ranges, forming Owens, Amorgosa, Saline, and Death Valley. The Sierras formed by winds from the west (not shown) that pressed against the Great Basin rotation and the winds bypassing south.
From the south, winds collected and then split, forming the Mexican Kink and the El Guaje mountain. They reformed in a ground-hugging laminar flow near Four Corners, sweeping across Colorado, Utah, and northern Arizona, laying down the foundations of the Colorado Plateau.
The main attractors for this wind were two coronal loops, one rising into a mesocyclone at San Rafael Reef and down-drafting into a mirror image crater defined by Capitol Reef in Utah. The other rising at Monument Valley, its shock wave defined by Comb Ridge, Arizona and down-drafting due south to rejoin the general counter-clockwise rotation over the Plateau in the region bordered by the San Juan River.
Winds from the south also circulated eastward over the Great Plains to be sucked into the Colorado Plateau cyclone through a row of coronal loops that built the eastern face of the Rockies. These down-drafted into tight cyclones, forming huge craters in the mountains, like San Luis Valley, Colorado.
Each of these features — the large Great Basin mesocyclone, the tightly wound cyclone over the Colorado Plateau, and the arching colonnades of coronal loops within the bigger cyclone which feed it, like thunderstorms feed a hurricane. It’s all the same fractal-ing thing.
So this completes the view of winds at the very eye of the storm. The Monument Valley and San Rafael Swell coronal loop storms caused the largest potential difference and hottest plasma torching in North America. Surrounding areas were also ravaged by storm but none so severely. In fact, the whole Earth was wrapped in storms. So, we’ll look closer at some of those regions, as well as more details on North America in the next instalment of Eye of the Storm.
Additional Resources by Andrew Hall:
Andrew Hall is a natural philosopher, engineer, and writer. A graduate of the University of Arizona’s Aerospace and Mechanical Engineering College, he spent thirty years in the energy industry. He has designed, consulted, managed, and directed the construction and operation of over two and a half gigawatts of power generation and transmission, including solar, gasification, and natural gas power systems. From his home in Arizona, he explores the mountains, canyons, volcanoes, and deserts of the American Southwest to understand and rewrite an interpretation of Earth’s form in its proper electrical context. Andrew was a speaker at the EU2016 and EU2017 conferences. He can be reached at [email protected] or thedailyplasma.blog
Disclosure: The proposed theories are the sole ideas of the author, as a result of observation, experience in shock and hydrodynamic effects, and deductive reasoning. The author makes no claims that this method is the only way mountains or other geological features are created.
The ideas expressed in Thunderblogs do not necessarily express the views of T-Bolts Group Inc. or The Thunderbolts Project. | 0.865999 | 3.455458 |
The spectrum acquired by GTC of interstellar comet C/2019 Q4 (Borisov) reveals that this object has a surface composition not unlike that found in Solar System comets.
Shortly before dawn on September 13th, Julia de León, Miquel Serra-Ricart, Javier Licandro, all members of IAC's Solar System Group, and Carlos Raúl de la Fuente Marcos, from the Complutense University of Madrid, obtained high resolution images and visible spectra of comet C/2019 Q4 (Borisov) using the OSIRIS instrument at the 10.4m GTC, installed in the Roque de los Muchachos Observatory (Garafía, La Palma). Observations were not easy, the object could only be seen at low elevation over the horizon and small angular separation from the Sun. However, thanks to the excellent atmospheric conditions of the Canarian Observatories and GTC's expert telescope support astronomerss, these challenging observations were successfully completed.
Miquel Serra Ricart points out that "the image of C/2019 Q4 shows a cometary object, with well-defined coma and tail". Julia de León adds that "the spectrum of this object is similar to those of Solar System comets and this indicates that their composition must be similar". Comets are made of ice and dust, they are ---in the words of Fred Whipple in 1950--- "dirty snowballs" formed in the outermost regions of a protoplanetary disc, where water is frozen because it is so far away from the central star. They are part of the debris left behind after the formation of the Giant planets. Comet C/2019 Q4 was discovered on August 30, 2019 by G. Borisov observing from the Crimean Astrophysical Observatory, when the object was nearly 3 AU from the Sun. The discovery was announced by the Minor Planet Center on September 11, 2019 stating that C/2019 Q4 is following a clearly hyperbolic path and that it is approaching the Sun at high speed. The comet will be closest to the Sun, at 2 AU, early in December and then it will head for interstellar space, leaving the Solar System, never to return. This is only the second confirmed interstellar visitor after interstellar object 1I/2017~U1 (`Oumuamua), discovered two years ago.
Comet C/2019 Q4 could not have formed in our Solar System as we know it, it has to have formed around a star other than the Sun and escaped from its gravitational attraction, probably millions of years ago. Comet C/2019 Q4 is the first clearly cometary object observed in the inner Solar System, but of extrasolar origin. Carlos and Raúl de la Fuente Marcos point out that their "direct N-body simulations that use the latest orbit determination place C/2019 Q4 well beyond the sphere of influence of the Solar System only 50,000 years ago, moving inbound at a velocity nearly 500 times higher than the escape velocity from the Solar System at that distance. In this context, it is difficult to exclude an extrasolar origin for C/2019 Q4."
For Javier Licandro, the results of this research "clearly show that comets in other planetary systems can be similar to those of the Solar System and they may have formed by processes similar to those which led to the formation of the Oort Cloud comets in the Solar System."
Article: "Interstellar Visitors: A Physical Characterization of Comet C/2019 Q4 (Borisov) with OSIRIS at the 10.4 m GTC", AAS20106. Preprint: https://www.dropbox.com/s/c8j9acjuce2fx3d/deLeonC2019Q4_V3.pdf?dl=0
Julia de León: jmlc [at] iac.es
MIquel Serra-Ricart: mserra [at] iac.es
Javier Licandro: jlicandr [at] iac.es
This project studies the physical and compositional properties of the so-called minor bodies of the Solar System, that includes asteroids, icy objects, and comets. Of special interest are the trans-neptunian objects (TNOs), including those considered the most distant objects detected so far (Extreme-TNOs or ETNOs); the comets and the comet-asteroid | 0.905133 | 3.968443 |
The Universe is permeated by hot, turbulent, magnetized plasmas. Turbulent plasma is a major constituent of active galactic nuclei, supernova remnants, the intergalactic and interstellar medium, the solar corona, the solar wind and the Earth’s magnetosphere, just to mention a few examples. Energy dissipation of turbulent fluctuations plays a key role in plasma heating and energization, yet we still do not understand the underlying physical mechanisms involved. THOR is a mission designed to answer the questions of how turbulent plasma is heated and particles accelerated, how the dissipated energy is partitioned and how dissipation operates in different regimes of turbulence. THOR is a single-spacecraft mission with an orbit tuned to maximize data return from regions in near-Earth space – magnetosheath, shock, foreshock and pristine solar wind – featuring different kinds of turbulence. Here we summarize the THOR proposal submitted on 15 January 2015 to the ‘Call for a Medium-size mission opportunity in ESAs Science Programme for a launch in 2025 (M4)’. THOR has been selected by European Space Agency (ESA) for the study phase. | 0.9023 | 3.214414 |
What do you get if you put 40 researchers and 12 technologically advanced experiments in an aircraft and fly at maximum thrust in repeated 49° angles at the limits of the aircraft’s design? Zero-gravity science, and this is exactly what is happening this week on the 72nd ESA parabolic flight campaign.
Parabolic flights offer repeated sessions of 20 seconds of zero gravity giving a total of 10 minutes of weightlessness each flight. The advantage of parabolic flights over other platforms for experimentation in altered gravity is that researchers can join the flight and interact with their experiment – fine tuning hardware, running tests on human subjects or changing parameters on the fly.
The experiments are carefully chosen for potential benefits, safety and uniqueness. This campaign, starting today, covers disciplines as diverse as astronomy, cooling techniques, metallurgy, weather and human physiology.
The Progra2 experiment is creating clouds of matter and recording how light is scattered by micrometre-sized particles. The carbon-based dust is chosen to resemble the clouds found in our Solar System such as around asteroids and comets. Knowing how light is scattered by these particles in microgravity will help interpret observations made from telescopes and increase our understanding the Universe.
The experiment is linked to the ICAPS experiment that is looking at what happens next when dust clouds interact in space – how they clump together to form larger bodies such as planets – ICAPS flew earlier this month but on a rocket offering six minutes of weightlessness.
Crumbs and jams
Somewhat unintuitively, larger particles move to the top when shaken – this is why the person to finish a packet of cornflakes ends with all the smaller crumbs. The VIP-GRAN team is looking into how particles behave in reduced gravity to understand the underlying physics in detail. For this flight they are investigating the jamming of particles as they flow through small openings. This can be an annoyance on Earth when salt get stuck in the shaker for example, but the phenomenon is influenced by gravity and the researchers want to know more. This will be the ninth flight for the VIP-GRAN team, who are working towards having a version of their experiment fly on the International Space Station with even more weightless time.
Picking up good vibrations, giving the excitations
The “Complex fluids under periodic excitations” experiment, shortened to Comflu is part of ESA’s long-running investigations into how liquids mix. For this flight the team will observe layers of normal fluids and non-Newtonian liquids that solidify like ketchup when you try to bash out the last drops from a bottle. The liquids will receive periodic vibrations from pistons at either end to force them to mix.
The goal for this experiment is to understand how microparticles mix with the viscoelastic fluids and will help understand how microplastics behave in liquids and their toxicity for aquatic organisms. The experiment is run in weightlessness to understand the process without gravity, adding complexity to the mathematical models.
ESA’s 72nd parabolic flight campaign will take place from the week of 25 November over three days. The teams are preparing their experiments and loading them onto the aircraft this week. Two experiments are part of the FlyYourThesis! initiative for university students. | 0.809905 | 3.167354 |
Also found in: Dictionary.
Lagrangian points(lă-grayn -jee-ăn) Five locations in space where a small body can maintain a stable orbit despite the gravitational influence of two much more massive bodies, orbiting about a common center of mass. They are named after the French mathematician J.L. Lagrange who first suggested their existence in 1772. A Lagrangian point 60° ahead of Jupiter in its orbit around the Sun, and another 60° behind Jupiter, are the average locations of members of the Trojan group of asteroids; these points are denoted L4 and L5. The three other Lagrangian points in the Sun–Jupiter gravitational field do not permit stable asteroid orbits owing to the perturbing influence of the other planets. In any system these three points lie on the line joining the centers of mass of the two massive bodies and are denoted L1 (the inner Lagrangian point) and L2 and L3 (the outer Lagrangian points); small bodies here would be in unstable equilibrium (see equipotential surfaces).
Lagrangian points[lə′grän·jē·ən ‚poins]
Five points in the orbital plane of two massive objects orbiting about a common center of gravity at which a third object of negligible mass can remain in equilibrium; three points of instable equilibrium are located on the line passing through the centers of mass of the two bodies, and two points of stable equilibrium are located in the orbit of the less massive body, 60° ahead of or behind it. | 0.858526 | 3.410919 |
Comet Hale-Bopp observed by SOHO/SWAN on April 3, 1997.
SOHO looks at a comet's shadow in space Depicted here is a series of three images of Comet Hale-Bopp's shadow taken by SOHO's SWAN instrument between 25 February, 1997 and 8 March, 1997. The blue-white monochrome images show a portion of the sky illuminated by the Sun's ultraviolet light. The Sun is shown as a round dot at the bottom. The bright white glow at the centre is a 150-million-kilometre-wide hydrogen cloud released by Hale-Bopp's nucleus.
As the comet neared the Sun, the water-ice nucleus began to vaporize. Ultraviolet radiation then split the water molecules, which freed the hydrogen. The resulting hydrogen cloud absorbed the ultraviolet light emitted by the Sun, which was no longer available to illuminate the background of interstellar hydrogen. That resulted in an elongated, 150-million-kilometre-long shadow of the comet projected in sky, which is visible in the upper part of each image.
The comet's movement in the sky (right to left) is evident by looking at the blue three-image sequence. The image bottom left is a schematic that depicts the geometry of the SWAN observations | 0.800364 | 3.674354 |
A group of astronomers is using a new method to search for hard to spot alien planets: By measuring the difference between the amount of light coming from the planets' daysides and nightsides, astronomers have spotted 60 new worlds thus far.
The researchers used data from NASA's Kepler space telescope to apply their technique. After training computers to hunt for the worlds, the researchers released the machines on over 140,000 stars. For their first dive into the data, the scientists targeted only stars with no known planets (although some of the systems are suspected to host planets). The computer program looked for changes in the amount of light coming from the star system that could be caused by the telescope alternately seeing a close-orbiting planet's dayside and then its nightside.
"We're searching for the light that the planets reflect from their host stars," Sarah Millholland, a graduate student at Yale University and a co-author of the paper, told Space.com by email. She and her co-author Greg Laughlin, a professor of astronomy at Yale, are using their program to identify exoplanets that otherwise would have been missed in the Kepler data. [7 Ways to Discover Alien Planets]
Normally, Kepler detects exoplanets via the transit method. As a planet passes between its star and the sun, the amount of light Kepler observes drops sharply because it has been blocked by the distant world, and rises again once the planet moves on. The researchers' new method also examines how starlight is changed by a passing planet, but in a whole new way.
"This [new] method of planet hunting uses the same kind of data as transits … but it involves looking for a different kind of signal in the data," Millholland said.
Traditionally, scientists have relied on a handful of methods to hunt for planets. One technique, called the radial velocity (RV) method, was the first to reveal a distant world, tracking how a massive planet can cause its parent star to wobble. And using another technique, called the direct imaging method, researchers snap photos of exoplanets, but that method can be applied only to large worlds orbiting far from their stars.
But thanks to the Kepler space telescope, the transit method rules the exoplanet roost. Over the course of its primary mission, which lasted about four years, Kepler revealed thousands of potential and confirmed worlds. (The Kepler spacecraft is now being used for a secondary mission, dubbed K2.) The spacecraft has a numbers advantage: Whereas instruments capable of searching for planets via the direct imaging and RV methods can focus on only one star at a time, Kepler can collect light from thousands of stars simultaneously.
But the transit method of searching for exoplanets also has limitations. For a planet to block the light of its star, it must orbit along the line of sight between Earth and the parent star. For every planet Kepler has spotted, there are likely another 99 that it couldn't see, according to an estimate by astronomy blogger and astrophysicist Ethan Siegel. That's an awful lot of missed worlds.
Millholland and Laughlin weren't content to leave all of those planets hidden. They used the Kepler data to look for worlds lit up by their parent stars, just like the sun lights up the face of the moon and the planets in our solar system (which is why planets in our solar system look like "stars" in the night sky). When an alien planet is on the near side of its star, it radiates a dim light from its nightside (from retained heat), and when the exoplanet is on the far side of the star, it reflects light from its parent star (the dayside). If those variations appear in the Kepler data, they can reveal a planet's presence.
After ensuring that the program could identify already-known, hot gas giants by their glow, the researchers turned their program loose on over 140,000 Kepler stars. The new technique turned up 60 previously unidentified gas giant candidates that don't transit their sun.
Due to limitations in its precision, Kepler can hunt only for the glow of close-in gas giant planets — the so-called hot Jupiters. Future instruments with increased precision could extend the method to smaller worlds, Millholland said.
Compared to the dazzling searchlight glow of a star, the glow from a planet is extremely faint. Stellar activity, such as sunspots and flares, have the potential to give false positives in the search for planets. That's why, Millholland said, any detections made with the new method should be followed up with RV-method measurements; they have not yet used RV to follow up on the 60 detections reported in the new study.
"RV observations are necessary to confirm the planet candidates," she said. (Many "objects of interest" detected by Kepler are also confirmed using RV measurements.) "Close-in giants produce large RV signals, so they should be readily detectable," Millholland said.
Millholland and Laughlin started out with stars with no known or suspected planets, but eventually, they plan to use the method to search for gas giants in systems already known to host small worlds.
This method could help solve the mystery of how and where hot Jupiters form, according to the authors.
Prior to the first discoveries of planets around other stars, planetary evolution models — which were based on Earth's solar system — set the birth of gas giants far from their stars, similar to where Jupiter and the other giant planets orbit the sun. So when the first exoplanet hunts revealed hot Jupiters, scientists were startled. The leading hypothesis became that these massive gassy worlds had migrated inward after forming at a distance.
But several years ago, some scientists proposed that hot Jupiters might have formed closer to their star. Laughlin is among those who question the migration model. Following another line of research, Laughlin predicted that hot Jupiters born near their stars would have small-mass sibling planets with orbits that are not aligned with the parent star's orbital plane. (In Earth's solar system, the eight planets orbit in a kind of flat disk around the sun.) Soon, he and Millholland plan to turn their attention toward known collections of rocky worlds with strange orbital alignments, in hunt of hidden gas giants.
The research was published in The Astronomical Journal on Aug. 4, which is the end of the Northern Hemisphere observing season for the Kepler field, Millholland said. She said several groups of scientists in the Northern Hemisphere plan to begin their hunt for the glowing worlds next spring.
"If we use this technique to find systems with hot Jupiters and misaligned small planets, it would be evidence toward this theory of hot-Jupiter formation," Millholland said. In the near future, the pair plans to use the method to probe stars that host oddly aligned rocky planets, after the 60 new worlds have been confirmed using the radial-velocity method.
"It would be best to study those systems separately," she said. | 0.873358 | 3.718638 |
With someresearchers predicting the onset of severe solar weather in a few years, NASAis planning to triple team the Sun by keeping one ancient craft alive toprovide critical support for two fancy new missions.
The SOHO spacecraft has been the workhorse of space weather forecasting since it beganobserving the Sun in 1995. It has weathered storms of its own, sufferingelectrical problems and various malfunctions that rendered it all but dead on morethan one occasion.
But SOHO (Solar and Heliospheric Observatory) has endured, longer than any othersolar-dedicated observatory. Designed as a two-year mission, funding to operatethe craft has been extended twice in the past so it could cover a complete11-year solar cycle.
And now,even though it is being upstaged by the more glamorous 3-D Solar TErrestrialRElations Observatory (STEREO)images, SOHO has received funding through 2009. Why? Turns out, there arecrucial observations only SOHO can do in the effort to monitor the raging Sun. Even next year, when the SolarDynamics Observatory (SDO) is slated to launch, SOHO will remain a vital part of thethree-mission observation team.
"SOHO hasbeen a godsend in terms of advancing our science in the years it's been up,"said Joseph Kunches, lead forecaster at the NOAA Space Environment Center. "SOHO has already taken us and lifted the whole profession up to the first floor of thebuilding from the basement, and now we're trying to go higher."
Currently,forecasters rely on statistics to predict when a storm will hit, for instanceusing information from an average magneticstorm. In contrast, the triple fleet will provide real-time information.Plus, rather than a window of, say, six hours, Kunches said the forecastersmight be able in the future to say that stormy conditions will clear up in thenext 45 minutes with some confidence.
"Right now,we have somebody standing at home plate and the Sun is the pitcher and it'sthrowing us these fast balls," Kunches said in a phone interview. STEREO willprovide "first-base and third-base coaches," watching what's comingfrom the "pitcher" to the "batter," he said. "They'll beable to tell us better than ever when [a pitch or a solar storm] is going toarrive at home plate, at the Earth."
Adding SDOto the team will be like a sharp-eyed umpire, upping the chances of "hittingone out of the park," he said, extending the analogy.
"We want tohit home runs. We want to know what's coming and be able to prepare for it asbest we can and get the word out," Kunches said.
The jury isstill out as to whether the coming solarcycle will be characterized by lots of intense solar storms or a calmperiod. There is strong evidence on both sides, Kunches said.
Considered SOHO's replacement, SDO is the first mission to be launched for NASA's Living With a Star(LWS) program, which aims to determine the causes of solar variability and howthese peaks and troughs in solar storms impact Earth.
But SOHO's Large Angle and Spectrometric COronagraph Experiment (LASCO) coronagraphs, whichroutinely capturemassive solar eruptions called coronal mass ejections (CMEs), can't bematched by either STEREO or SDO. These major storms sometimes slam into Earth,threatening satellites, communications and even terrestrial power grids.
"LASCOis the only show in town," said Bernhard Fleck, SOHO project scientist atNASA's Goddard Space Flight Center in Greenbelt, Md.
The LASCOinstrument uses a Sun-shade to block out the main body of the Sun, simulating asolar eclipse. That way, astronomers can watch activity in the Sun's outeratmosphere, which is up to 10 million times fainter than the light from thesolar disk. Without the bright-light blocker, forecasters would not be able toobserve a solar ejection inthe corona and beyond, a step that is crucial for forecasting how such spaceweather might impact Earth.
"Thisinstrument is capable of observing what is happening in the high atmosphere ofthe Sun," said Guillermo Stenborg, SOHO-LASCO operations scientist at Goddard.
One set ofinstruments aboard SOHO monitors solar activity in the disk itself, and oncethe charged ejections reach the outer atmosphere LASCO's coronagraphs takeover, tracking the event in interplanetary space out to a distance of 432,000miles (695,500 kilometers) from the Sun.
If itsurvives long enough, SOHO will also be used for the crucial task ofcalibrating SDO to make more accurate readings of the data it collects.
Meanwhile,Fleck told SPACE.com, he and other SOHO engineers are working toautomate SOHO mission procedures and observations to "fly verycheaply." Instead of scientists monitoring the status of instruments, "thiswill be done by computers which will alert the spacecraft engineers andinstrument teams in case of an anomaly," Fleck said. "The plan is to move tounmanned night passes in the fall."
If SOHO can hang in there, it will also make up for a shortcoming of the STEREO mission plan.STEREO's two spacecraft are drifting apart at about 45 degrees each year. Withinfour years, the probes will be so widely spaced they won't be watching theportion of the Sun that faces us, and they won't be able to properly monitorhow solar storms will affect Earth.
SOHO can fill in the gap.
"SOHOis actually the third eye of STEREO," Fleck said, and even now many ofSTEREO's observations are enhanced by adding SOHO data. In order to whip up a 3-Dimage, astronomers need three points of reference, so STEREO's twins providetwo points while SOHO generates the third.
Currently, SOHO and its instruments appear in good shape, and Stenborg said battery power (a typicalreason for instrument conk-outs on an old mission) is not an issue.
Stenborgsaid most of the instruments will be decommissioned a year or two after SDO islaunched, which is set for August 2008. "They will be taken out of operationexcept for LASCO and a couple of other instruments, especially because SDO hasno LASCO kind of instrument," he said.
- Images: Sun Storms
- Top 10 Sun Images from SOHO
- Mysteries of the Sun | 0.808243 | 3.107156 |
IRSPEC (Infrared Spectrometer) was a multi-purpose spectrometer first installed on the ESO 3.6-metre telescope in the mid-1980s.
Spectrometers collect and separate wavelengths of light to produce what is called a spectra. Spectra can be analysed to learn about the composition, speed, and a number of other characteristics of astronomical objects. IRSPEC gathered near-infrared wavelengths, which allowed astronomers to study gas and dust rich astronomical objects, such as newborn stars.
Cold liquid nitrogen ran throughout IRSPEC to lower the temperature of the optical components to -193 ºC and the detector to -223 ºC. Heat generated from running the instruments can contaminate the data with heat noise, so cooling instruments can create sharper spectra.
Data taken with IRSPEC formed part of a number of studies during the 1980s and 1990s, including the research of comets, supernova, and nebula. In 1994, researchers used IRSPEC to search for molecules in the impacts of Shoemaker-Levy 9 on Jupiter (eso9402).
After several years on the ESO 3.6-metre telescope, IRSPEC was installed as one of the first instruments on the New Technology Telescope (NTT) in 1989. Developments in infrared technology during the 1990s resulted in more sensitive infrared instruments, and when compared to new technology, the IRSPEC suffered from more noise. In 1997, SOFI (Son of ISSAC) spectrograph therefore replaced IRSPEC on the NTT.
This table lists the global capabilities of the instrument. | 0.844679 | 3.343677 |
Possible signature of dark matter annihilation detected
We live in a dramatic epoch of astrophysics. Breakthrough discoveries like exoplanets, gravitational waves from merging black holes, or cosmic acceleration seem to arrive every decade, or even more often. But perhaps no discovery was more unexpected, mysterious, and challenging to our grasp of the "known universe" than the recognition that the vast majority of matter in the universe cannot be directly seen. This matter is dubbed "dark matter," and its nature is unknown. According to the latest results from the Planck satellite, a mere 4.9% of the universe is made of ordinary matter (that is, matter composed of atoms or their constituents). The rest is dark matter, and it has been firmly detected via its gravitational influence on stars and other normal matter. Dark energy is a separate constituent.
Understanding this ubiquitous yet mysterious substance is a prime goal of modern astrophysics. Some astronomers have speculated that dark matter might have another property besides gravity in common with ordinary matter: It might come in two flavors, matter and anti-matter, that annihilate and emit high energy radiation when coming into contact. The leading class of particles in this category are called weakly interacting massive particles (WIMPS). If dark matter annihilation does occur, the range of options for the theoretical nature of dark matter would be considerably narrowed.
CfA astronomer Doug Finkbeiner and a team of colleagues claim to have identified just such a signature of dark matter annihilation. They studied the spatial distribution of gamma-ray emission in the Milky Way, in particular gamma-ray emission from the Galactic Center region. This region is both relatively nearby and has a high matter density (and nominally a high dark matter density as well). If dark matter annihilation occurred, the location would be expected to be bright in gamma-rays. Indeed, a large gamma-ray signature has been seen from the area that extends over hundreds of light-years (there is also fainter emission extending outward for thousands of light-years). There are other possible explanations, however, most notably that the gamma-rays result from a large population of rapidly spinning pulsars, the nuclear ashes of some supernovae.
The scientists revisited the set of previously published gamma-ray observations, applying careful new data reduction methods in order to constrain more precisely the location of the emission, and they did so for each of the several observed energy regimes of the gamma-ray emission. Pulsars have a distinctive spatial distribution: they are located where stars are found, predominantly in the plane of the galaxy. The team was able to show with high significance that the distribution of gamma-ray emission is in good agreement with the predictions of simple annihilating dark matter models, but less likely to be consistent with a pulsar explanation. Their result, if confirmed, would be an impressive breakthrough in the understanding of the nature of dark matter, the dominant constituent of the cosmos. | 0.888705 | 4.25557 |
NASA research reveals Saturn is losing its rings at ‘worst-case-scenario’ rate
New NASA research confirms that Saturn is losing its iconic rings at the maximum rate estimated from Voyager 1 & 2 observations made decades ago. The rings are being pulled into Saturn by gravity as a dusty rain of ice particles under the influence of Saturn’s magnetic field.
“We estimate that this ‘ring rain’ drains an amount of water products that could fill an Olympic-sized swimming pool from Saturn’s rings in half an hour,” said James O’Donoghue of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “From this alone, the entire ring system will be gone in 300 million years, but add to this the Cassini-spacecraft measured ring-material detected falling into Saturn’s equator, and the rings have less than 100 million years to live. This is relatively short, compared to Saturn’s age of over 4 billion years.” O’Donoghue is lead author of a study on Saturn’s ring rain appearing in Icarus December 17.
Scientists have long wondered if Saturn was formed with the rings or if the planet acquired them later in life. The new research favors the latter scenario, indicating that they are unlikely to be older than 100 million years, as it would take that long for the C-ring to become what it is today assuming it was once as dense as the B-ring. “We are lucky to be around to see Saturn’s ring system, which appears to be in the middle of its lifetime. However, if rings are temporary, perhaps we just missed out on seeing giant ring systems of Jupiter, Uranus and Neptune, which have only thin ringlets today!” O’Donoghue added.
Various theories have been proposed for the ring’s origin. If the planet got them later in life, the rings could have formed when small, icy moons in orbit around Saturn collided, perhaps because their orbits were perturbed by a gravitational tug from a passing asteroid or comet.
The first hints that ring rain existed came from Voyager observations of seemingly unrelated phenomena: peculiar variations in Saturn’s electrically charged upper atmosphere (ionosphere), density variations in Saturn’s rings, and a trio of narrow dark bands encircling the planet at northern mid-latitudes. These dark bands appeared in images of Saturn’s hazy upper atmosphere (stratosphere) made by NASA’s Voyager 2 mission in 1981.
In 1986, Jack Connerney of NASA Goddard published a paper in Geophysical Research Letters that linked those narrow dark bands to the shape of Saturn’s enormous magnetic field, proposing that electrically charged ice particles from Saturn’s rings were flowing down invisible magnetic field lines, dumping water in Saturn’s upper atmosphere where these lines emerged from the planet. The influx of water from the rings, appearing at specific latitudes, washed away the stratospheric haze, making it appear dark in reflected light, producing the narrow dark bands captured in the Voyager images.
Saturn’s rings are mostly chunks of water ice ranging in size from microscopic dust grains to boulders several yards (meters) across. Ring particles are caught in a balancing act between the pull of Saturn’s gravity, which wants to draw them back into the planet, and their orbital velocity, which wants to fling them outward into space. Tiny particles can get electrically charged by ultraviolet light from the Sun or by plasma clouds emanating from micrometeoroid bombardment of the rings. When this happens, the particles can feel the pull of Saturn’s magnetic field, which curves inward toward the planet at Saturn’s rings. In some parts of the rings, once charged, the balance of forces on these tiny particles changes dramatically, and Saturn’s gravity pulls them in along the magnetic field lines into the upper atmosphere.
Once there, the icy ring particles vaporize and the water can react chemically with Saturn’s ionosphere. One outcome from these reactions is an increase in the lifespan of electrically charged particles called H3+ ions, which are made up of three protons and two electrons. When energized by sunlight, the H3+ ions glow in infrared light, which was observed by O’Donoghue’s team using special instruments attached to the Keck telescope in Mauna Kea, Hawaii.
Their observations revealed glowing bands in Saturn’s northern and southern hemispheres where the magnetic field lines that intersect the ring plane enter the planet. They analyzed the light to determine the amount of rain from the ring and its effects on Saturn’s ionosphere. They found that the amount of rain matches remarkably well with the astonishingly high values derived more than three decades earlier by Connerney and colleagues, with one region in the south receiving most of it.
The team also discovered a glowing band at a higher latitude in the southern hemisphere. This is where Saturn’s magnetic field intersects the orbit of Enceladus, a geologically active moon that is shooting geysers of water ice into space, indicating that some of those particles are raining onto Saturn as well. “That wasn’t a complete surprise,” said Connerney. “We identified Enceladus and the E-ring as a copious source of water as well, based on another narrow dark band in that old Voyager image.” The geysers, first observed by Cassini instruments in 2005, are thought to be coming from an ocean of liquid water beneath the frozen surface of the tiny moon. Its geologic activity and water ocean make Enceladus one of the most promising places to search for extraterrestrial life.
The team would like to see how the ring rain changes with the seasons on Saturn. As the planet progresses in its 29.4-year orbit, the rings are exposed to the Sun to varying degrees. Since ultraviolet light from the Sun charges the ice grains and makes them respond to Saturn’s magnetic field, varying exposure to sunlight should change the quantity of ring rain. | 0.869525 | 3.656075 |
Back in February I wrote about a fairly decent SF novel I was reading, Coyote by Allen Steele (it had some problems, but I liked it well enough to read the sequel, Coyote Rising). Coyote is a "novel of interstellar exploration" that starts in 2070 and involves hundreds of colonists traveling for 230 years (in "biostasis") at 20% the speed of light to reach a star system 46 light years from Earth. There they wake up and land on the fourth moon of a Saturn-like gas giant planet orbiting in the habitable zone of its star. This Earth-like moon was named "Coyote."
Today NASA announced the discovery of a fifth planet orbiting the star 55 Cancri, 41 light years from here in the constellation Cancer (more info including a cool video here). It is a remarkable achievement of observation, data collection, Doppler-shift measurement, and data reduction to tease out the properties of the star's five individual planets from 18 years of observational data from California's Lick Observatory.
What's even cooler is that while the fifth planet (which is actually the fourth in distance from its star) is also a gas giant (45 times the mass of Earth), its orbital distance (116.7 million kilometers, orbital period 260 days) puts it within the habitable zone of its star (closer to the star than we are to the sun, but the star is fainter than the sun). That means that if it has any rocky moons orbiting it, they could have liquid water on their surfaces, and where there's liquid water, there could be... you get the idea.
Of course no moons have been detected yet, but all the gas giants of our solar system have them, and it's reasonable to assume that extra solar gas giants would as well. So "Coyote" could be there, and it's 5 light years closer than in Steele's novel! Now we need to get to work on giant space-based optics so we can image those exoplanetary moons, not to mention the star ship and propulsion systems that will give us 0.2c, and the robotics and biostatasis system that will let our intrepid colonists sleep for 200 or so years on the way to their new home. This is left as an exercise for the reader.
Update: For anyone interested in more details and serious discussion, this post in Centauri Dreams is a good place to start. The comments have additional details including a link to a PDF preprint of the five-planet paper by the scientific team. As Paul notes, we are indeed entering what seems to be a golden age of exoplanet research. | 0.890166 | 3.168781 |
Halley’s Comet won’t swing by Earth for another 48 years, but you won’t have to wait that long to watch bits of the iconic comet zip across our skies. That’s because this weekend Earth smashes into a stream of material, known as the Eta Aquarid meteors, shed from the speedy iceberg in years past. (Related: Ancient Greeks Made First Halley’s Comet Sighting?)
Coming through the inner solar system every 76 years, Halley melts a bit from the heat of the sun and sheds some pounds as gas, dust, and rocks break off. All this material then gets deposited in clouds of debris which follow the same orbit as the comet.
The result of this cosmic diet the comet undergoes is an annual shooting-star show, which this year is set to peak in the predawn hours of May 5, with rates of 10 to 50 meteors an hour – depending on local sky conditions. Our planet plows through the densest part of Halley’s debris cloud Saturday night into Monday morning.
While not as spectacular as its August cousin, the Perseids, the cool factor for sky-watchers is that all those modest shooting stars are bits of debris from Halley’s Comet. One other shower – the Orionids in October – shares the same royal pedigree. (Related: See ‘Postcards’ from Halley’s Comet)
No telescopes or binoculars required to enjoy the show – just unaided eyes so that you can soak in as much of the overhead skies. The meteors will appear to radiate out from the constellation Aquarius – rising in the southeast around 3 am local time. Aquarids are known to be fast and bright, and because the waning crescent moon rises only around morning twilight, skywatchers stuck in light polluted suburbs should be able to catch at least a dozen per hour early Sunday morning. Best views will be from the Southern Hemisphere with meteor counts decreasing as you head into the Northern Hemisphere – by mid northern latitudes Aquarids tend to be falling at a trickle.
Halley’s last paid a visit back in 1986 and won’t return until 2061, but with some clear skies and patience, we can still marvel at its tiny but flashy, cosmic offspring this weekend. | 0.870302 | 3.418364 |
Image: Hubble stares into the crammed center of Messier 22
This image shows the center of the globular cluster Messier 22, also known as M22, as observed by the NASA/ESA Hubble Space Telescope. Globular clusters are spherical collections of densely packed stars, relics of the early years of the Universe, with ages of typically 12 to 13 billion years. This is very old considering that the Universe is only 13.8 billion years old.
Messier 22 is one of about 150 globular clusters in the Milky Way and at just 10,000 light-years away it is also one of the closest to Earth. It was discovered in 1665 by Abraham Ihle, making it one of the first globulars ever to be discovered. This is not so surprising as it is one of the brightest globular clusters visible from the northern hemisphere, located in the constellation of Sagittarius, close to the Galactic Bulge—the dense mass of stars at the center of the Milky Way.
The cluster has a diameter of about 70 light-years and, when looking from Earth, appears to take up a patch of sky the size of the full Moon. Despite its relative proximity to us, the light from the stars in the cluster is not as bright as it should be as it is dimmed by dust and gas located between us and the cluster.
As they are leftovers from the early Universe, globular clusters are popular study objects for astronomers. M22 in particular has fascinating additional features: six planet-sized objects that are not orbiting a star have been detected in the cluster, it seems to host two black holes, and the cluster is one of only three ever found to host a planetary nebula—a short-lived gaseous shells ejected by massive stars at the ends of their lives. | 0.895657 | 3.572639 |
In 1960, famed theoretical physicist Freeman Dyson made a radical proposal. In a paper titled “Search for Artificial Stellar Sources of Infrared Radiation” he suggested that advanced extra-terrestrial intelligences (ETIs) could be found by looking for signs of artificial structures so large, they encompassed entire star systems (aka. megastructures). Since then, many scientists have come up with their own ideas for possible megastructures.
Like Dyson’s proposed Sphere, these ideas were suggested as a way of giving scientists engaged in the Search for Extra-Terrestrial Intelligence (SETI) something to look for. Adding to this fascinating field, Dr. Albert Jackson of the Houston-based technology company Triton Systems recently released a study where he proposed how an advanced ETI could use rely on a neutron star or black hole to focus neutrino beams to create a beacon.
To summarize briefly, the existence of megastructures depends entirely on where an extra-terrestrial civilization would fit into the Kardashev Scale (i.e. if they are a planetary, stellar, or galactic civilization). In this case, Jackson suggests that a Type II civilization would be capable of enclosing a neutron star or black hole through the creation of a large constellation of neutrino-transmitting satellites.
Dr. Jackson begins his study with a quote from Freeman Dyson’s 1966 essay, “The Search for Extraterrestrial Technology”, where he summarized his aims:
“So the first rule of my game is: think of the biggest possible artificial activities with limits set only by the laws of physics and look for those.
In a previous study, Dr. Jackson suggested how advanced ETIs could use small black holes as a gravitational lens to send gravitational wave signals across the galaxy. This concept builds upon recent work by other researchers who have suggested that gravitational waves (GWs) – which have become the focus of considerable research since they were first detected in 2016 – could be used to transmit information.
In another paper, he also ventured how a sufficiently-advanced civilization could use the same type of lens to create a laser beacon. In both cases, the technological requirements would be staggering and would require infrastructure on a stellar scale. Taking this a step further, Dr. Jackson explores the possibility of neutrinos being used to transmit information since they, like GWs, travel well through the interstellar medium.
Compared to focused beams of photons (aka. lasers), neutrinos have a number of advantages as far as beacons are concerned. As Dr. Jackson told Universe Today via email:
“Neutrinos arrive almost without attenuation from any source direction, this would have [a] big advantage in the Galactic plane. Photons in wavelengths like the infrared are also good with gas and dust (why the Webb is an IR scope) still there is some absorption. Neutrinos can travel across the universe almost without absorption.”
As for the process through which such a beacon could be created, Jackson once again refers to Freeman Dyson’s guiding rule on how ETIs could go about creating any type of megastructure. This rule is simply, “if the physics allows it, it is possibly technologically feasible.” In the case of a Type II civilization, the engineering requirements would be beyond our comprehension, but the principle remains sound.
Basically, the concept takes advantage of a phenomenon known as gravitational lensing, where scientists rely on the presence of a massive intervening object to focus and magnify light coming from a more distant object. In this case, the light source would be neutrinos, and the effect of focusing them would make for a stronger beacon signal. As Jackson explained:
“Place a source of neutrinos in orbit about a black hole or neutron star. The black hole or neutrons star are best because they are very compact objects. A black hole or neutron star is a gravitational lens, this lens focuses the neutrinos (it could be photons or gravitons) into an intense beam. This beam when seen at a distance is so ‘tight’ one has to place a constellation of neutrino ‘transmitters’ about the gravitational lens in order to get an approximate isotropic transmitter. In this case the number of ‘transmitters’ is about , or about a billion times the number of stars in the Milky Way Galaxy.”
Much like building a Dyson Sphere, this sort of engineering undertaking would only be possible for a species that had effectively become a Type II civilization. In other words, a civilization capable of harnessing and channeling the energy radiated by its own star, which amounts to about ~4×1033 erg/sec (or 4×1026 watts) of energy – which is several trillion times what humanity currently consumes on an annual basis.
Another interesting possibility arising from this is its implications for SETI. Given that a sufficiently-advanced extra-terrestrial species could be communicating via neutrinos, scientists could use existing detectors to pinpoint the sources. In this respect, focused neutrino beams could be added to the list of possible “technosignatures” – i.e. signs of technological activity – being sought out by SETI researchers.
“There are a number of ‘neutrino telescopes’ around the world,” Jackson stated. “If an advanced civilization beacon exists it could produce a very anomalous number of neutrino events, way above the natural sources of neutrinos such [as] the sun or supernova.. this would be an addition to the candidates for signs of advanced technological activity.”
To summarize things with another quote from one of Dyson’s famous essays:
“When we look into the universe for signs of artificial activities, it is technology and not intelligence that we must search for. It would be much more rewarding to search directly for intelligence, but technology is the only thing we have any chance of seeing.”
As we learn more about the Universe and become more advanced as a species, it opens our mind to new possibilities in the ongoing search for life. If and when we do find evidence of ETIs, it is entirely possible it will be because we’ve learned finally learned to read the signatures of their existence correctly. In the meantime, the search continues…
Further Reading: arXiv
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Tokyo: Scientists have discovered 15 new planets - including one ‘super-Earth’ that could harbour liquid water - orbiting small, cool stars near our solar system. These stars, known as red dwarfs, are of enormous interest for studies of planetary formation and evolution.
The team led by Teruyuki Hirano of Tokyo Institute of Technology in Japan validated 15 exoplanets orbiting red dwarf systems. One of the brightest red dwarfs, K2-155 that is around 200 light years away from Earth, has three transiting super-Earths, which are slightly bigger than our own planet.
Of those three super-Earths, the outermost planet, K2-155d, with a radius 1.6 times that of Earth, could be within the host star’s habitable zone. The findings, published in The Astronomical Journal, are based on data from Nasa Kepler spacecraft’s second mission, K2, and follow-up observations using ground-based telescopes, including the Subaru Telescope in Hawaii and the Nordic Optical Telescope (NOT) in Spain.
The researchers found that K2-155d could potentially have liquid water on its surface based on 3D global climate simulations. A more precise estimate of the radius and temperature of the K2-155 star would be needed to conclude definitively whether K2-155d is habitable.
Achieving such precision would require further studies, for example, using interferometric techniques, researchers said. A key outcome from the current studies was that planets orbiting red dwarfs may have remarkably similar characteristics to planets orbiting solar-type stars.
“It’s important to note that the number of planets around red dwarfs is much smaller than the number around solar-type stars," said Hirano. “Red dwarf systems, especially coolest red dwarfs, are just beginning to be investigated, so they are very exciting targets for future exoplanet research," he said. | 0.899686 | 3.543946 |
Over the past two and half centuries, scientists envisioning the origin of planetary systems (including our own) have focused on a specific scene: a spinning disk around a newborn star, sculpting planets out of gas and dust like clay on a potter’s wheel.
But as for testing the idea, by actually spotting an exoplanet coalesce from swirling matter? No luck yet. “Nowadays, everybody says planets form in protoplanetary disks,” said Ruobing Dong, an astrophysicist at the University of Arizona.“This sentence is, technically, a theoretical statement.”
Advances over the past few years suggest it won’t stay theoretical for long. Using second-generation instruments mounted on giant ground-based telescopes, several teams have finally resolved the inner regions of a few protoplanetary disks, uncovering unexpected, enigmatic patterns.
The latest views came on April 11, when the European Southern Observatory released eight images of disks around young, sunlike stars, perhaps illustrating what our own solar system looked like in its infancy.
The images don’t show clear, unambiguous points of lights from planets. But these and other systems do contain tantalizing — albeit indirect — hints that infant planets may be hiding within. Some disks are like a vinyl record, with rings and gaps that could have been carved out by young worlds. In others, starlight illuminates both a top and bottom surface of the disk, forming a structure that resembles a yo-yo.
If astronomers could find an embryonic planet in a place like this, the payoff would be far-reaching. Beyond just proving one of astronomy’s deepest-held ideas, the quantitative measurement of where a planet is forming, and at what size, would immediately help differentiate between battling theories of how planets are born.
One account of planet formation, called core accretion, holds that planets form slowly, coalescing around rocky cores, and in a region close to their stars. Another theory appeals to gravitational instabilities in the disk, suggesting giant planets can coalesce quickly, far away from their stars. Currently, these ideas can be tested against the distribution of current planets in our solar system and extrasolar systems. But they’ve never been studied with the process still under way, before planets have a chance to migrate and rearrange themselves.
That gives astronomers who study these systems a unifying, unfinished quest. Look at dim, distant, untidy disks. Hunt down baby planets. And at long last, after centuries of anticipation, begin to unravel the fundamental processes that shape countless worlds across the universe.
When searching for planets in protoplanetary disks, it’s easy to convince yourself that you’re seeing them. Astronomers who study these disks have already spotted multiple specks of light hiding inside. As recently as May 6, for example, an international team reported signs of a giant planet lurking in a system called CS Cha. But for now these specks remain mere planetary candidates, not confirmed worlds.
“We’re at the very hairy edge of the technology,” said Katherine Follette, an astronomer at Amherst College. “In the case of planets embedded in disks, absolutely every single one of them is still debated heavily.”
This ambiguity is intimately tied to the same messy environments that would make these planets special.
One instrument leading the search is SPHERE, mounted on the Very Large Telescope in Chile’s Atacama Desert, which obtained the eight recent protoplanetary disk images. Another, which Follette works on, is the Gemini Planet Imager (GPI), a rival instrument on another Chilean mountain.
Both were designed to catch photons from planets around other stars, unlike most techniques for studying exoplanets that rely on more indirect signatures. Both also produce data that’s easiest to interpret when they’re trained on uncluttered, older solar systems where disks have already eroded.
These cameras need ways to peel faint pinpricks of light away from bright host stars, like finding a firefly sitting on the rim of a distant spotlight. They use adaptive optics, a technology that tracks fluctuations in the atmosphere and then warps its own optics in real time to compensate. This cancels out Earth’s roiling air, de-twinkling the night sky to achieve higher resolution. They also use coronagraphs, which block out light from the star.
And on top of that, these planet-hunting cameras employ yet another trick called differential imaging. SPHERE, for example, takes two simultaneous pictures through different polarized filters. Starlight itself isn’t polarized, so the star looks the same in both versions. It can be subtracted away. But when light scatters, it gets polarized. This allows astronomers to accentuate the photons that have bounced off a disk or a planet.
Algorithms then search for leftover points of light. But when looking for planets within disks, the algorithms can confuse clumps and clouds for newborn worlds.
Follette and colleagues have spent the past few years trying to analyze these false signals. They’ve also studied puzzling planet candidates, including some that don’t seem to be orbiting their host star in accordance with Kepler’s laws of motion, as all planets would.
Meanwhile, there’s another path to planets unfolding in parallel. Although SPHERE and GPI haven’t unambiguously found a forming world, they have managed to take the sharpest-ever pictures of protoplanetary disks themselves.
Finally seen up close, these disks host a menagerie of strange features that may be linked to planet formation. “That has completely changed the game,” said Konstantin Batygin, an astrophysicist at the California Institute of Technology. “It has been revolutionary.”
The problem lies in associating these features with the putative planets causing them. And that’s not easy, either. “We talk about disks as signposts of planets,” said Follette. “But if they’re signposts of planets, they’re ones that we have no idea how to interpret yet.”
Consider a striking pattern first noticed in 2012. In at least half a dozen protoplanetary disks, something seems be winding gas and dust into seashell whorls like the arms of spiral galaxies.
Astrophysicists have two main ideas to explain what’s making these spiral arms. Both borrow from a decades-old theory of galactic spirals. According to this idea, gas and dust spinning around a newborn star begin to pile up in a celestial traffic jam. Something has to trigger the initial snarl-up, however.
Astronomers have suggested that in stars surrounded by heavy disks — those that weigh at least a quarter as much as the star they orbit — gravitational instabilities can cause pileups of material into spiral arms. But researchers have found many spiral disks that appear to be far below this mass threshold, intimating that another mechanism may be at work.
Perhaps a hidden puppeteer is to blame. In 2015, a team led by Dong, the Arizona astrophysicist, built simulations that showed how giant planets a little bigger than Jupiter could trigger spiral whorls, too. The planet would sit right at the tip of one the arms and drag the spiral along as it orbited the star. If this is the case, every spiral is like a giant arrow pointing toward the field’s ultimate quarry — a planet in the process of being born.
In 2016, Dong’s team found evidence that these spirals can be triggered by a massive body. In this case, the triggering object orbiting the star HD 100453 was a dwarf star, which is easier to spot than a planet. But it served as a proof of concept. “After that, people started believing more in the model,” Dong said.
Finding an arm-tip planet itself would seal the deal, but astronomers are still waiting. In an recent paper in The Astrophysical Journal Letters, a team led by Bin Ren, a researcher at Johns Hopkins University, gathered and analyzed data from MWC 758’s spiral going back more than a decade.
Over this time, Ren’s analysis shows, the whorls may have rotated ever so slightly, at about six tenths of a degree per year. This rotation would be expected from a giant planet out at the tip of an arm that orbits the star every 600 years or so, Ren said. But such a planet, if it exists, is still hiding.
Of course, even if spirals are conclusively linked to planets, they won’t lead the way to all newborn worlds. In simulations, only gas giant planets are hefty enough to draw spiral patterns. Smaller worlds would have to be discovered through other means. And not all protoplanetary disks host spirals, either.
For example, none of the new SPHERE images of disks around sunlike stars have spiral arms. (That suggests the spiral process, whatever it is, may be more efficient around more massive stars, said Henning Avenhaus of the Max Planck Institute for Astronomy in Heidelberg.) But they and many other protoplanetary disks do show something else, something perhaps even more promising: gaps.
Planets in the Cracks
In the fall of 2014, astronomers testing ALMA, a collection of radio dishes in the Chilean Andes, decided to train it on the most massive protoplanetary disk they could find. When the resulting picture of empty gaps and thick rings in a system called HL Tauri was later displayed at an internal ALMA meeting, it stopped the show.
“We just spent the rest of the meeting talking about HL Tau,” said Lucas Cieza, an astronomer at Diego Portales University in Chile. Looking at the gaps, the assembled scientists debated whether they were produced by planets. ALMA scientists later studied images of another, nearby system called TW Hydrae, which show similar gaps in even higher detail. But neither system can settle the issue of whether the gaps are caused by planets or by something else. “The debate is still ongoing,” Cieza said.
Just like spirals, both planets and other effects can sculpt gaps. A planet would carve out a gap over thousands to millions of years. As it orbits, it would both pull disk material in toward itself as well as scatter it away from the planet’s orbit, leaving an empty groove.
This gravitational engraving would be cumulative. While it takes something bigger than Jupiter to make a spiral, worlds the size of Neptune or even as small as Earth could create noticeable gaps, said Jeffrey Fung, an astrophysicist at the University of California, Berkeley.
“All of these planets have the potential to open deep enough gaps that we can easily see with today’s instruments,” he said. Crucially, these gaps might be the only near-term chance to study the formation of small planets, which would be even more difficult than Jupiter-size worlds to spot directly in a disk.
What might be making these gaps if not planets? The magnetic field of a disk can lead to regions of turbulence, sweeping material away from what become empty, magnetic “dead zones.” Or abrupt changes in chemistry can cause a gap that also mimics the action of a planet. A solar system’s snow line, for example, marks the boundary between the hot inner disk, where water exists as vapor, and the outer disk, where water freezes into solid grains. Similar transitions occur for other compounds, like carbon monoxide and ammonia.
The confusion leaves astronomers searching for an answer key. “The best-case scenario is we actually see a planet in a gap,” said Fung. Technically, current technology would not pick up a planet itself, but a smaller, circumplanetary disk of material falling onto one. If such a signal could be linked to a spiral or gap, it would help observers start translating back and forth between worlds and disk features more generally.
The wait might not be too long. “The most exciting things that I have seen are not published,” said Cieza, who declined to comment on specifics. “We can expect a lot of very exciting things coming in the next few months.”
Next-generation telescopes should also be able to help. The James Webb Space Telescope will be able to peer inside disks in infrared wavelengths and look directly for planets. Its launch has recently been delayed again, this time to 2020.
And the challenge of catching planet formation in the act is “a beautiful science case” for 30-meter-class telescopes, said Bruce Macintosh of Stanford University, who leads the GPI team. Observatories that size, like the Extremely Large Telescope currently being constructed in Chile, will be able to resolve even smaller structures inside protoplanetary disks.
Whenever it happens, confirmed cases of forming planets will be “groundbreaking,” Dong said. What used to be a mathematical bedtime story of the birth of worlds would be playing out in real time, in real data. “It’s related to the fundamental question of where we come from.”
This article was reprinted on Wired.com. | 0.942379 | 3.996248 |
The WISE spacecraft has completed a special mission called NEOWISE, looking for small bodies in the solar system, and has discovered a plethora of previously unknown objects. The NEOWISE mission found 20 comets, more than 33,000 asteroids in the main belt between Mars and Jupiter, and 134 near-Earth objects (NEOs). More data from NEOWISE also have the potential to reveal a brown dwarf even closer to us than our closest known star, Proxima Centauri, if such an object does exist. Likewise, if there is a hidden gas-giant planet in the outer reaches of our solar system, data from WISE and NEOWISE could detect it.
“WISE has unearthed a mother lode of amazing sources, and we’re having a great time figuring out their nature,” said Edward (Ned) Wright, the principal investigator of WISE at UCLA.
“Even just one year of observations from the NEOWISE project has significantly increased our catalog of data on NEOs and the other small bodies of the solar systems,” said Lindley Johnson, NASA’s program executive for the NEO Observation Program.
The NEOs are asteroids and comets with orbits that come within 45 million kilometers (28 million miles) of Earth’s path around the sun.
The NEOWISE mission made use of the the WISE spacecraft, the Wide-field Infrared Survey Explorer that launched in December 2009. WISE scanned the entire celestial sky in infrared light about 1.5 times. It captured more than 2.7 million images of objects in space, ranging from faraway galaxies to asteroids and comets close to Earth.
However, in early October 2010, after completing its prime science mission, the spacecraft ran out of the frozen coolant that keeps its instrumentation cold. But two of its four infrared cameras remained operational, which were still optimal for asteroid hunting, so NASA extended the NEOWISE portion of the WISE mission by four months, with the primary purpose of hunting for more asteroids and comets, and to finish one complete scan of the main asteroid belt.
Now that NEOWISE has successfully completed a full sweep of the main asteroid belt, the WISE spacecraft will go into hibernation mode and remain in polar orbit around Earth, where it could be called back into service in the future.
In addition to discovering new asteroids and comets, NEOWISE also confirmed the presence of objects in the main belt that had already been detected. In just one year, it observed about 153,000 rocky bodies out of approximately 500,000 known objects. Those include the 33,000 that NEOWISE discovered.
NEOWISE also observed known objects closer and farther to us than the main belt, including roughly 2,000 asteroids that orbit along with Jupiter, hundreds of NEOs and more than 100 comets.
These observations will be key to determining the objects’ sizes and compositions. Visible-light data alone reveal how much sunlight reflects off an asteroid, whereas infrared data is much more directly related to the object’s size. By combining visible and infrared measurements, astronomers also can learn about the compositions of the rocky bodies — for example, whether they are solid or crumbly. The findings will lead to a much-improved picture of the various asteroid populations.
NEOWISE took longer to survey the whole asteroid belt than WISE took to scan the entire sky because most of the asteroids are moving in the same direction around the sun as the spacecraft moves while it orbits Earth. The spacecraft field of view had to catch up to, and lap, the movement of the asteroids in order to see them all.
“You can think of Earth and the asteroids as racehorses moving along in a track,” said Amy Mainzer, the principal investigator of NEOWISE at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “We’re moving along together around the sun, but the main belt asteroids are like horses on the outer part of the track. They take longer to orbit than us, so we eventually lap them.”
NEOWISE data on the asteroid and comet orbits are catalogued at the NASA-funded International Astronomical Union’s Minor Planet Center, a clearinghouse for information about all solar system bodies at the Smithsonian Astrophysical Observatory in Cambridge, Mass. The science team is analyzing the infrared observations now and will publish new findings in the coming months.
The first batch of observations from the WISE mission will be available to the public and astronomical community in April. | 0.877015 | 3.874506 |
A star that is roughly 16,300 light-years away from the sun was inexplicably being flung around at speeds of several hundred kilometers per hour — or so we thought.
The group of international astronomers that observed the star inside of a cluster called NGC 3201 in the Vela constellation knew that the only possible intergalactic object that could be causing it to do this is a black hole that was hiding among thousands of other stars.
In a research paper published in the Monthly Notices of the Royal Astronomical Society on January 9, the team detailed how they were able to detect this “lonely black hole” inside of NGC 3201. This is the first black hole that has been discovered without the help of X-rays or radio waves and it’s the first one to ever be discovered in these this type of cluster.
Globular star clusters are spherical collections of tens of thousands of stars that can be found in most galaxies and are one of the oldest known stellar systems. Due to the age of these clusters and the sheer number of stars found inside them they are thought to have produced a sizable number of stellar-mass black holes — or black holes formed by the gravitational collapse of a massive star.
By utilizing the MUSE instrument on the European Southern Observatory’s Very Large Telescope in Chile, the team was able to track the erratic movements of this one star to prove it was being moved by a black hole 4.36 times the Sun’s mass, which is actually pretty small by black hole standards.
The fact that this star was not being swallowed up let the astronomers know that this newfound black hole is also inactive, which means it’s not currently devouring matter that comes too close.
“Until recently, it was assumed that almost all black holes would disappear from globular clusters after a short time and that systems like this should not even exist,” Benjamin Giesers, the lead author of the paper, in a statement. “But clearly this is not the case…This finding helps in understanding the formation of globular clusters and the evolution of black holes and binary systems — vital in the context of understanding gravitational wave sources.”
Previous studies have suggested that black holes may be more common inside of globular clusters than previously thought. This discovery certainly bolsters that argument and gives astronomers an idea for what to look for when they’re looking for inactive black holes in the future. | 0.878397 | 3.858999 |
News Release 08-204
Planetary "First Family" Discovered By Astronomers Using Gemini and Keck Observatories
First direct images of a planetary familly around a normal star observed
November 13, 2008
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Astronomers using the Gemini North telescope and W.M. Keck Observatory on Hawaii's Mauna Kea, the tallest mountain in the Hawaiian chain, have obtained the first-ever direct images identifying a multi-planet system around a normal star.
The Gemini images allowed the international team to make the initial discovery of two of the planets in the confirmed planetary system with data obtained on Oct. 17, 2007. Then, on Oct. 25, 2007, and in the summer of 2008, the team, led by Christian Marois of the National Research Council of Canada's Herzberg Institute of Astrophysics in Victoria, British Columbia, and members from the U.S. and U.K., confirmed this discovery and found a third planet orbiting even closer to the star with images obtained by the Keck II telescope. These historic infrared images of an extra-solar multiple-planet system were made possible by adaptive optics technology used to correct in real time for atmospheric turbulence, the shimmering or blinking of starlight as it passes through the earth's atmosphere.
"This discovery is significant--it is the first time a family of planets around a normal star outside of our solar system was imaged," said Brian Patten, program manager at the National Science Foundation. "Scientists may now directly view planets themselves, as opposed to indirectly through a star's spectrum or its brightness."
Research results will be published in the Nov.13, 2008, issue of Science Express, an international weekly science journal.
The host star, a young, massive star called HR 8799, is about 130 light years away from Earth. Comparison of multi-epoch data shows that the three planets are all moving with, and orbiting around, the star, proving that they are associated with it rather than just unrelated background objects coincidentally aligned in the image.
The planets, which formed about 60 million years ago, are young enough that they are still glowing from heat released as they contracted, making them easier to see in infrared light. Analysis of the brightness and colors of the objects at multiple wavelengths shows that these objects are about seven and 10 times the mass of Jupiter. As in our solar system, these giant planets orbit in the outer regions of this system--at roughly 25, 40, and 70 times the Earth-Sun separation. The furthest planet orbits just inside a disk of dusty debris, similar to that produced by the comets of the Kuiper Belt objects of our solar system just beyond the orbit of Neptune at 30 times the Earth-Sun distance. In some ways, this planetary system seems to be a scaled-up version of our solar system orbiting a larger and brighter star.
HR 8799 observations are part of a survey of 80 such young, dusty, and massive stars located in the solar neighborhood. The survey is using adaptive optics systems at Gemini, Keck and VLT in Chile to constrain the Jupiter-mass planet populations in a range of separations inaccessible to other exoplanet detection techniques. This discovery was made after observing only a few stars, which may lead to the conclusion that Jupiter-mass planets at separations similar to the giant planets of our solar system are frequent around stars more massive than the Sun, Marois said. "HR 8799's planetary system will be studied in great detail in the years to come, and it will surely be a prime target for future next-generation, exoplanet finding instruments and dedicated space missions."
About the Gemini Observatory
The Gemini Observatory is an international partnership involving the United States, the United Kingdom, Canada, Australia, Chile, Brazil and Argentina. The partnership has constructed and now operates two 8-meter telescopes: one in the Northern Hemisphere on Mauna Kea, Hawaii, and one in the Southern Hemisphere on Cerro Pachon, Chile. The twin telescopes are infrared-optimized, have superb image quality, and provide unprecedented optical and infrared coverage of the northern and southern skies for astronomical research. Scientific operations began on Gemini North in 2000 and on Gemini South in 2001.
NSF acts as the executive agency for the partnership, and the Association of Universities for Research in Astronomy Inc.--a consortium of 33 U.S. universities and institutions and seven international affiliates--manages the Gemini Observatory. The Astronomy Division also provides the U.S. share of funding for the operation of the observatory.
Gemini Observatory discovery image using the Altair adaptive optics system on Gemini North.
Credit and Larger Version
Brian M Patten, NSF, (703) 292-4910, email: [email protected]
Bruce Macintosh, Lawrence Livermore National Laboratories, Livermore, CA, (925) 423-8129, email: [email protected]
The U.S. National Science Foundation propels the nation forward by advancing fundamental research in all fields of science and engineering. NSF supports research and people by providing facilities, instruments and funding to support their ingenuity and sustain the U.S. as a global leader in research and innovation. With a fiscal year 2020 budget of $8.3 billion, NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and institutions. Each year, NSF receives more than 40,000 competitive proposals and makes about 11,000 new awards. Those awards include support for cooperative research with industry, Arctic and Antarctic research and operations, and U.S. participation in international scientific efforts. | 0.882833 | 3.627369 |
The fast asteroid is expected to swing along the so-called Earth-moving trajectory. According to NASA, the closest approach to the asteroid will occur on the afternoon of Halloween, October 31st. When that happens, NASA estimates that the space rock will reach speeds of about 19 215 mph (30,924 km / h).
What do we know about the 2019 UJ3 asteroid?
Astronomers have called the rocky body Asteroid 2019 UJ3 since its discovery on October 19 this year.
The cosmic rock is an Apollo-type asteroid, which means that it orbits the Earth in an orbit similar to the 1862 Apollo Apollo.
NASA has also classified an asteroid near the Earth or NEO.
NEOs are all comets and asteroids in orbital trajectories that approach astronomically our planet.
READ MORE: NASA just traced two large rocks flying past Earth
In most cases, NEOs pass harmlessly across our planet without threatening them.
But if the NEO is large enough to warrant NASA interest, the space agency will closely monitor its prognosis. [1
"If a comet or asteroid approach brings it to 1.3 astronomical units of the Sun, it is an object near Earth. ”
The 2019 UJ3 asteroid is thought to measure anywhere in the range of 55.7 feet to 124.6 feet (17 meters to 38 meters) in
Will the 2019 UJ3 asteroid hit Earth on Halloween?
Fortunately, NASA does not expect UJ3 to come close enough to pose a threat to Earth.
The asteroid will approach Earth from a distance of about 0.01871 astronomical units.
An astronomical unit is the distance from Earth to the Sun – about 93 million miles (149.6 million km).
The asteroid UJ3 will shorten this to just 1.7 million miles (2.79 million km) on Halloween night.
NASA said, "As they orbit the orbit of the sun, near-Earth objects can sometimes approach close to Earth.
"Note that the" near "astronomical passage can be very far in human terms: millions or even tens of millions of kilometers. "
Quick facts about asteroids and other cosmic rocks:
1. Some of the larger objects in the asteroid belt are approximately 583 miles long.
2. NASA estimates that a car-sized asteroid collides with the Earth about once a year.
3. According to the Cosmic Space Rock, cosmic rocks the size of a football field descend on the planet about once every 2,000 years.
4. If a meteor survives a descent through the atmosphere, it is called a meteorite.
5. Comets are different from asteroids because they are covered in ice layers that sublimate in space. | 0.812349 | 3.03133 |
Oct 03, 2012
Thermonuclear fusion reactions from deep in the core are said to drive the Sun.
Hypothetically, how does the Sun produce heat and light enough to sustain life on Earth at a mean distance of 149,476,000 kilometers?
According to spectrographic analysis, the Sun is composed primarily of hydrogen gas (71%), with 27% helium and the remainder thought to be minute percentages of oxygen, nitrogen, sulfur, carbon, and six other elements. Although every element on Earth can be seen in a spectrogram of the Sun, those 12 make up 99.9% of its mass
The Sun is 1,390,000 kilometers in diameter, with a mass approximation of 1.98 X 10^30 kilograms. The temperature measured at its surface is 5800 Kelvin and is estimated to be as high as 15,600,000 Kelvin in the core. As conventional models suggest, the Sun must generate outward radiation pressure or gravity would compress it into a relatively tiny, solid ball. The theory states that an energy source must exist inside the Sun, acting as a counter force to gravitational contraction.
Sir Arthur Eddington is considered to be the “father” of stellar nucleosynthesis with the publication of his book, The Internal Constitution of the Stars in 1929, although nuclear fusion had not been discovered at that time. It was in 1938 that Hans Bethe developed the proton-proton reaction hypothesis that would, he supposed, provide enough energy to power the Sun. The proton-proton cycle is now “known” to be the source for 98% of solar energy production.
Standard theory states that when the Sun condensed out of the nebular cloud that is supposed to have been its nursery, the gases were compressed by gravity until they reached temperatures greater than ten million Kelvin. At that temperature, hydrogen atoms are disrupted into individual protons and electrons, leaving the protons free to collide with one another. It is these initial proton collisions, it is said, that are the first step in a reaction called the proton-proton (p-p) chain, as mentioned above.
When protons collide at those high temperatures, they are thought to be moving fast enough for them to fuse into other particles: deuterium, a positron and a neutrino. Deuterium is a proton-neutron combination, while a positron is a positively charged electron. Neutrinos are conventionally thought to be similar to electrons, except they do not carry an electric charge and are almost massless. Being neutral, they are said to not be affected by the electromagnetic forces that affect electrons.
The second stage in the p-p reaction is the formation of a helium-3 nucleus when the deuterium captures another proton, while at the same time emitting a gamma ray. A helium-4 nucleus and two neutrinos are the end results of the reaction, although it can follow one of many different reaction paths.
In reality, as Electric Universe theorist Wal Thornhill points out, stars reside within plasma sheaths perhaps as great as a light-day in extent. “It is clear from the behavior of its relatively cool photosphere that the Sun is an anode, or positively charged electrode, in a galactic discharge. The red chromosphere is the counterpart to the glow above the anode surface in a discharge tube. When the current density is too high for the anode surface to accommodate, a bright secondary plasma forms within the primary plasma. It is termed ‘anode tufting.’ On the Sun, the tufts are packed together tightly so that their tops give the appearance of ‘granulation.’”
The stars receive their power from outside, not inside. Any nuclear reactions are taking place on the surface of the Sun and not in its core. The solar wind is an electric current connecting the Sun with its family of planets and with its galactic clan, so the 90-year-old theory of fusion firing the solar furnace needs to be reexamined. | 0.867809 | 3.925113 |
Space debris is becoming more of an issue as time goes on with the number of objects doubling in the last 15 years. Part of that problem is inevitable as the stage based approach to rocketry, whilst being the most efficient way to transport mass to orbit, unfortunately leaves behind a considerable amount of mass. This, combined with the numerous defunct satellites and other bits of junk, means that our lower orbits are littered with objects hurtling through space with enough force to cause some rather significant damage to anything else we put up there. Solving this problem isn’t easy as just picking it up is far more complicated than it sounds. Thus researchers have long thought of ideas to tackle this issue and scientists working at the RIKEN institute may have come up with a workable solution for some of the most dangerous and hardest to remove debris out there.
The idea comes off the back of the Japanese Experiment Module – Extreme Universe Space Observatory (JEM-EUSO) telescope which is slated to be launched and installed on the International Space Station sometime in 2017. The telescope is designed to use the Earth’s atmosphere as a giant detector for energetic particles which will leave a trail of light behind them as they decay in the Earth’s atmosphere. The design of the telescope, which consists of three large lenses that direct the light to some 137 photodetector modules, means it has an extremely wide field of view. Whilst this is by design for its primary mission it also lends itself well to detecting space debris over a large area, something which is advantageous to the ISS which needs to do everything it can to avoid them.
However that’s only half the solution; the other half is a freaking laser.
Scientists at the RIKEN institute have posited that using something like the CAN laser, which is a fibre based laser that was originally designed for use in particle accelerators, could then be used to zap space junk and send it back down to Earth. This kind of approach only works for debris that are centimeters in size however they’re among some of the most devastating pieces of junk due to the difficulty in detecting them. With the JEM-EUSO however these bits of debris could be readily identified and, if they’re within the reach of the laser, heated up so their orbit begins to decay.
The current plan is to develop a proof of concept device that uses a 1/10th scale version of the current JEM-EUSO telescope combined with a 100 fiber laser. Whilst they haven’t provided any specifications beyond that going off their full scale design (10,000 fibers) the concept should be able to deorbit debris up to a kilometer away. The full scale version on the other hand would be able to zap space junk at a range of up to 100km, an incredible feat that would dramatically help in cleaning up Earth’s orbit. The final stage would be to develop a standalone satellite that could be put into a 800km polar orbit, one of the most cluttered orbits above Earth.
Our approach to tackling space debris is fast becoming a multi-faceted approach, one that will require many different methods to tackle the various types of junk that we have circling our Earth. Things like this are the kind of approach we’ll need going forward as one launch will be able to eliminate several times its own mass in debris before its useful life is over. It’s far from an unsolvable problem however whatever solutions we develop will need to be put to use soon lest our low orbits become a place that no man can ever venture through again.
Time is a strange beast. As far as we know it always appears to go forward although strange things start to occur in the presence of gravity. Indeed if you synchronized two atomic clocks together then took one of them on a trip around the world with you by the time you got back they’d be wildly out of sync, more than they ever could be through normal drift. This is part of Einstein’s theory of general relativity where time appears to speed up or slow down due to the differing effects of gravity on the two objects which results in time dilation. This effect, whilst so vanishingly small as to be inconsequential in day to day life, becomes a real problem when you want to tell super accurate time, to the point where a new atomic clock might be worthless for telling the time.
Most atomic clocks in the world use a caesium atom to tell time as they transition between two states with an exact and measurable frequency. This allows them to keep time with incredible precision, to the point of not losing even a second of time over the course of hundreds of millions of years. Such accurate time keeping is what has allowed us to develop things like GPS where accurate time keeping allows us to pinpoint locations with amazing accuracy (well, when it’s not fuzzed). However a new type of atomic clock takes accuracy to a whole new level, being able to keep time on the scale of billions of years with pinpoint precision.
The Strontium Optical Atomic Clock comes from researchers working at the University of Colorado and can hold perfect time for 5 billion years. It works by suspending strontium atoms in a framework of lasers and then giving them a slight jolt, sending the atoms oscillating at a highly predictable rate. This allows the researchers to keep time to an incredibly precise level, so precise in fact that minor perturbations in gravity fields have a profound impact on how fast it ticks. As it turns out Earth is somewhat of a gravitational minefield thanks to the tectonic plates under its surface.
You see the further away you are from the Earth’s core the weaker its gravitational pull is and thus time passes just a little bit faster the further away you get. For us humans the difference is imperceptible, fractions of a fraction second that would barely register even if you found yourself floating billions of kilometres away in almost true 0g. However for a time instrument as sensitive as the one the researchers created minor changes in the Earth’s makeup greatly influence its tick rate, making accurate time keeping an incredibly difficult job. Indeed the researchers say that these clocks are likely to only be able to truly useful once we put one in space, far beyond the heavy gravitic influences that are found here on Earth.
It’s amazing that we have the ability to create something like this which throws all our understanding and perceptions around such a common and supposedly well understood phenomenon into question. That, for me, is the true heart of science, uncovering just how much we don’t know about something and then hunting down answers wherever they may lie. Sure, often we’ll end up having more questions when we come out of the end of it but that’s just a function of the vastness of the universe we live in, one that’s filled with ceaseless wonders that we’re yet to discover.
A common misconception that many people have around vaccines is that they’re a one shot deal that provides you with complete immunity from the disease in question. The efficacy of a vaccine is judged by how much it lowers the incident rate of a particular disease given ideal conditions and typically that number is high enough that herd immunity takes care of the rest. The flu vaccine is a great example of a vaccine that doesn’t provide full immunity to the disease in question (due to its highly mutable nature) but it does however give your immune system some tools with which to fight off variants of the disease should you get infected. Thus anything we can do to improve the efficacy of vaccines is important and it just so happens that lasers might be the next big thing.
Researchers at the Massachusetts General Hospital in conjunction with the Harvard-MIT Division of Health Science and Technology investigated the application of a cosmetic laser to an injection site prior to administering a vaccine. The research was primarily focused on improving the efficacy and duration of the protection offered by the influenza vaccine as its current levels could do with some improvement. The results they found were quite interesting, showing a 4 to 7 fold increase in immune response to the vaccine. Interestingly the results could not be replicated by simply increasing the dose of the vaccine, signalling that there was another mechanism in effect. The results also lend credence to one line of thinking of how adjuvants work, opening up new avenues for research.
Cosmetic lasers work by stimulating the body’s in built healing processes. Essentially they damage your dermis (without damaging the outer layer of skin) which causes an inflammation response at the site. For cosmetic purposes this is desirable as it promotes the renewal of skin cells at that site, making the skin look more youthful. For vaccines however this inflammatory response brings antigen-presenting cells to the site, the cells which are responsible for binding to pathogens or other harmful cells, which when faced with the vaccine rapidly bind to it. Interestingly enough the effect is most pronounced when used in conjunction with a typical adjuvant (Imiquimod, a topical cream) which also promotes an immune response at the site.
Interestingly this isn’t the first time that trauma at the injection site was used to promote the immune response. The smallpox vaccine used a bifurcated (split in two) needle which caused a rather unnerving wound at the injection site. This reduced the amount of vaccine required by about 4 times and resulted in the same effect, drastically reducing the cost required to vaccinate large populations. The cosmetic laser is a better approach due to the way it’s administered, reducing the chance for opportunistic infections and nocebo effects that might arise from the treatment.
Best of all whilst the research focused primarily on the influenza vaccine the same method appears to work for some of the other common vaccines. It’s still early days though as there’s a wide range of vaccines out there that will need to be tested with this method before it becomes standard procedure. Still anything that increases the effectiveness of an already high effective tool is great news as it means that these diseases will become less prevalent and, hopefully, we can reduce our mortality rates from them as well.
But also it’s just so freaking cool that lasers (LASERS!) are the things making vaccines better. It makes me unreasonably happy, for some reason… 🙂
Do you remember the Microwave Power Plant in Sim City 2000? The idea behind them was an intriguing one, you launched a satellite into orbit with a massive solar array attached and then beamed the power back down to Earth using microwaves that were collected at a giant receiver. Whilst it worked great most of the time there was always the risk that the beam would stray from its target and begin setting fire to your town indiscriminately, something which the then 11 year old me thought was particularly hilarious. Whilst we’ve yet to see that idea (or the disasters that came along with it, but more on that in a moment) the idea of putting massive solar arrays in orbit, or on a nearby heavenly body, are attractive enough to have warranted significant study.
The one limiting factor of most satellite based designs though is that they can’t produce power constantly due to them getting occluded for almost half their orbital period by Earth. Shimizu Corporation’s idea solves this issue in the most fantastical way possible: by wrapping our moon in a wide band of solar panels, enabling it to generate power constantly and beam it back down to Earth. Such an endeavour would seem like so much vapourware coming from anyone else but Shimizu is one of Japan’s leading architectural and engineering firms with annual sales of $14 billion. If there’s anyone who could make this happen it’s them and it aligns with some of the more aggressive goals for space that the Japanese government has heavily invested in of late.
The idea is actually quite similar to that of its incarnation in Sim City. Since the Moon is tidally locked with Earth (I.E. one side of the moon always points towards us) there only needs to be a single base station on the moon. Then a ring of solar panels would then be constructed all the way around the Moon, ensuring that no matter what the position of Moon, Earth and the Sun there will always be an illuminated section. There would have to be multiple base stations on Earth to receive the constantly transmitted power but since the power beams would be pointable they needn’t be placed in any particular location.
Of course such an idea begs the question as to what would happen should the beam be misaligned or temporarily swing out of alignment, potentially roasting anything in the nearby vicinity. For microwaves this isn’t much of a threat since the amount of power delivered per square meter is relatively low with a concentrated burst of 2 seconds barely enough to raise your body temperature by a couple degrees. A deliberately mistargeted beam could do some damage if left unchecked but you could also combat it very easily by just putting up reflectors or the rectilinear antennas to absorb it. The laser beams on the other hand are designed to be “high density” so you’d want some rigorous safety systems in place to make sure they didn’t stray far from the course.
Undertaking such a feat would require several leaps in technology, not least of which would be in the automation of its construction, but it’s all based on sound scientific principles. It’s unlikely that we’ll even see the beginnings of something like this within the next couple decades but as our demand for power grows options like this start to look a lot more viable. I hope Shimizu pursues the idea further as they definitely have the resources and know how to make it happen, it’s all a question of desire and commitment to the idea.
When I first wrote about Planetary Resources early last year I was erring on the side of cautious optimism because back then there wasn’t a whole lot of information available regarding how they were actually going to achieve their goal. Indeed even their first goal of building and launching multiple space telescopes sounded like it was beyond the capabilities of even veteran players in this industry. Still the investors backing them weren’t the type to be taken for a ride so I figured they were worth keeping an eye on to see how they progressed towards their goal.
And boy have they ever:
The above video shows off one of their prototypes of the Arkyd-100 space based telescope. Now back when Planetary Resources first started talking about what they were going to do I wasn’t expecting something of this size. Indeed I don’t believe anyone has attempted to make a space based telescope that small before as you’re usually trying to amp up your light gathering potential with a large mirror. Still despite the relatively small mirror size they should be quite capable of doing the required imagery that will lead them to potential mineable asteroids.
Their communications set up is also highly intriguing as traditional space communications require large dishes and costly receiving equipment back here on earth. Planetary Resources are instead looking to use lasers for their deep space communications an idea that I didn’t think would be possible. A quick bit of research turns up this document from NASA’s Jet Propulsion Lab which goes into some detail about their feasibility and shockingly it appears to only be an engineering challenge at this point. How long it will take to turn it into something usable remains to be seen but considering Planetary Resources are looking to launch within the next couple years I’d hazard a guess that they’re already pretty close to getting it working.
Looking at all this you’d think I’d be ashamed of my initial scepticism but I’m not, I love it when people prove me wrong like this. Indeed the work that Planetary Resources are doing closely resembles that of the early days of SpaceX, a company which has gone on to achieve things that no other private company has done before. Given enough time it’s looking like Planetary Resources will be able to do the same and that gets me all kinds of excited. | 0.915256 | 3.75464 |
- Published on 05 February 2014
Albert Einstein accepted the modern cosmological view that the universe is expanding, only long after several of his contemporaries had demonstrated it with astrophysical observations
Until 1931, physicist Albert Einstein believed that the universe was static. An urban legend attributes this change of perspective to when American astronomer Edwin Hubble showed Einstein his observations of redshift in the light emitted by far away nebulae—today known as galaxies. But the reality is more complex. The change in Einstein’s viewpoint, in fact, resulted from a tortuous thought process. Now, in an article published in EPJ H, Harry Nussbaumer from the Institute of Astronomy at ETH Zurich, Switzerland, explains how Einstein changed his mind following many encounters with some of the most influential astrophysicists of his generation.
- Published on 23 April 2013
Earlier this year Francesco Guerra, who had been a member of the editorial board of EPJ H - Historical Perspectives on Contemporary Physics since its launch in 2010, joined Wolf Beiglböck in managing the journal.
Prof. Francesco Guerra, a graduate from the University of Naples, is full professor of theoretical physics at the University of Rome 'La Sapienza'. He has served on many national academic evaluation committees and is currently a member of the Physics Panel of the National Agency for the Evaluation of Universities and Research.
His scientific interests include quantum field theory and elementary particles, stochastic methods in quantum mechanics, stochastic variational principles, statistical mechanics of spin glasses and complex systems, and the history of modern physics (in particular nuclear physics). In 2008, he was the recipient of the Italian Physical Society’s Prize for History of Physics.
- Published on 04 February 2013
A new study reveals the contribution of a little known Austrian physicist, Friedrich Hasenöhrl, to uncovering a precursor to Einstein famous equation
An American physicist outlines the role played by Austrian physicist Friedrich Hasenöhrl in establishing the proportionality between the energy (E) of a quantity of matter with its mass (m) in a cavity filled with radiation. In a paper just published in EPJ H, Stephen Boughn from Haverford College in Pensylvannia argues how Hasenöhrl’s work, for which he now receives little credit, may have contributed to the famous equation E=mc2.
- Published on 04 April 2011
The work behind the discovery of cosmic rays, a milestone in science, involved many scientists in Europe and the New World fascinated by the puzzling penetrating radiation, and took place during a period characterized by lack of communication and by nationalism caused primarily by World War I. It took eventually from the turn of the century until 1926 before the extraterrestrial nature of the penetrating radiation was generally accepted.
- Published on 01 November 2010
There is a divide, in quantum statistical physics, between the "ensemblists" who regard thermal equilibrium as a property of an ensemble (or a mixed state) and the "individualists" who regard thermal equilibrium as a property of an individual system (in a pure state). A long forgotten concept of equilibrium put forward by John von Neumann in 1929 is reanalyzed and shown to be influenced by both approaches, yet to be mainly based on the individualist view - a view that has gained ground recently. | 0.855645 | 3.407535 |
With the annual Perseid Meteor Shower already underway, we’re looking to the skies and thinking about what causes these celestial fireworks. We know for the most part that meteor showers are the by-product of comets, but what happens when seemingly random meteors become not so random? The answer is a long term comet which could be pointed right at Earth.
Comets don’t just wander through the Solar System. They take very specific paths around the Sun and when its orbit passes close to ours, we get visual clues in the form of a meteor shower. Long term comets are in no hurry. Their elliptical sojourns can take anywhere from 200 to 10,000 years to complete – with a dense dust trail leading the way. We compute when and where the comet comes from by its orbital period, but what happens if that orbital period leads to a new discovery? And what happens if that comet’s orbit seems destined to encounter us? We just might get some advance warning from monitoring an unexpected meteor shower.
“Such meteor showers are extremely rare. They happen only about once or twice every sixty years, when the thin meteoroid stream is exactly in Earth’s path at the time when Earth arrives at that spot.” says Peter Jenniskens (SETI Institute) and Peter S. Gural (SAIC). “Because they are so rare, many of these showers remain to be discovered. Here, we report that one such shower, previously unknown, just showed up on February 4, 2011.”
Thanks to the use of the new NASA-sponsored network of low-light video cameras called the Cameras for Allsky Meteor Surveillance (CAMS) project, more than three hundred “new” meteor showers documented by the IAU Working List of Meteor Showers are under investigation. The February 4 occurrence centered around Eta Draconis came as a surprise, but the observing team of three separate stations went to work confirming the meteoroid orbital elements. The event lasted around seven hours and was confirmed through astrometric tracks for all moving objects in all cameras that recorded that night and with radio reflections during that day taken in Finland.
“The similarity of the orbits implies that the February eta Draconids are a dynamically young stream. The orbital period suggests a long-period comet, perhaps a Halley-type comet. If this indeed is a long-period comet dust trail, then the dust was ejected in the previous return to the Sun.” says Jenniskens and Gural. “Such dust trails get perturbed enough on the way in that the orbital periods change dramatically and dust trail sections catch up on each other, spreading out into a more diffuse stream already after one orbit.”
Oddly enough, no meteoritic activity from this new stream was recorded either before or after its February 4th apparition… nor was it active between 2007 through 2009. The conclusion is that it’s caused by the dust trail of a long period comet and it has formally been named the February Eta Draconids. What long term comet does the stream belong to? Well, the answer to that question is still up in the air and a good point to ponder while viewing this year’s Perseids.
“This is an important discovery, because it points to the presence of a potentially hazardous comet. If the dust trail can hit the Earth, so can the comet: the planetary perturbations do not depend on the mass of the object.” says the team. “Of course, an impact will occur only if the comet orbit is perturbed into Earth’s path right at the time when Earth passes by the comet orbit on February 4. It is in principle possible to guard against such impacts by looking along the comet orbit to those spots where the comet would be in such a dangerous position. In that way, perhaps a few years of warning could be provided.”
Original New Story: Space.Com. | 0.853168 | 4.012702 |
May 23, 2012
One of the largest “active galaxies” is thought to be powered by a supermassive black hole. Electrical energy is a more likely driving force.
A recent press release from the European Southern Observatory (ESO) announces that the elliptical galaxy Centaurus A is ejecting a light-years long jet of material because a “supermassive black hole [is] at its heart”. Astronomical theories state that the radio-bright nucleus and the jet come from the compression of interstellar material as it is drawn into a central black hole possessing a mass greater than 100 million average stars.
From gamma-rays down through X-rays and extreme ultraviolet, conventional theories have relied on gravity and acceleration for radiation to be produced in space. Compressing hydrogen gas and dust is supposed to create enough transfer of momentum that it reaches temperatures in the millions of degrees. That high temperature is supposed to make the gas and dust glow brightly and emit high-frequency radiation.
Since the idea that electricity flows through the Universe is commonly met with resistance by today’s consensus, its influence and attributes are unseen. It has long been said that “seeing is believing”. However, it should not be surprising that “believing is seeing” appears to be more apt. When there is no inner experience, outer realities can often remain invisible.
Electric currents surge out along galactic spin axes, forming double layers that, like those in Centaurus A, can be seen as radio “lobes.” The electric charges spread out around the galactic circumference, flowing back to the core along the spiral arms. Since the elements in a galactic circuit radiate energy, that energetic radiance shows that they are powered by larger circuits. The extent of the larger circuits may be traced by radio telescopes through the polarized radio “noise” coming from them.
The fact that moving charges constitute an electric current that can generate magnetic fields has been known since the days of Michael Faraday. However, a lack of appropriate training often means a lack of vision. As previously stated, moving charged particles constitute an electric current, and that current is wrapped in a magnetic field. When more charged particles accelerate in the same direction, the field gets stronger.
Something that researchers do not consider is that for charged particles to move, they must move in a circuit. Energetic events cannot be explained by local conditions, alone. The effects of an entire circuit must be considered. For that reason, while the consensus scientific worldview only permits isolated “islands” in space, the Electric Universe emphasizes connectivity with an electrically active network of “transmission lines” composed of Birkeland current filaments.
Double layers and plasmoids expand and explode, throwing off plasma that can accelerate to near light-speed. Jets from opposite poles of a galaxy end in energetic clouds emitting X-ray frequencies, or radio waves. Those phenomena are based in plasma science and not gas kinetics, gravity, or particle physics. Astrophysicists see magnetic fields but not the underlying electricity, so they are at a loss to explain them.
Astronomers maintain that galaxies are clouds of hydrogen gas and intergalactic dust that were assembled by gravity until they coalesced into glowing thermonuclear fires. The conventional community also proposes that most galaxies contain black holes of unbelievable magnitude. It is those “gravitational point sources” that are supposed to cause the galaxies to spin, jets of gamma-rays to appear, and the radio lobes to form.
The Electric Universe theory does not adhere to the idea of galaxies condensing out of cold, inert hydrogen and specks of zircon no bigger than a molecule. So, what are galaxies?
In 1981, Hannes Alfvén said that galaxies are much like one of Michael Faraday’s inventions, the homopolar motor. A homopolar motor is driven by magnetic fields induced in a circular conducting plate. The plate is mounted between the poles of an electromagnet, causing it to spin at a rate proportional to the input current.
Galaxies move within filamentary circuits of electricity that flow through the cosmos from beginning to end. We see the effects of those electromagnetic fields because electricity organizes itself within masses of plasma sometimes larger than galaxy clusters. That plasma is primarily composed of neutral atoms, but free electrons, protons, and other charged particles are also present.
Plasma’s behavior is governed by those circuits. Double layers with large voltages between them often exist. The electric forces in double layers are incomparably stronger than gravity. Double layers broadcast radio waves over a wide range of frequencies. Most significant to the ESO bulletin, they can accelerate charged particles to extreme energies.
This vision of the cosmos sees various components coupled to and driven by circuits at ever larger scales, so electrons and other ions accelerated through intense electric fields radiate “shouts” of energy in many bandwidths. It is that story that should be told and not the one about omnipotent gravity. | 0.872542 | 3.993879 |
Detecting metals in invisible galaxies. Image credit: ESO Click to enlarge
Astronomers, using the unique capabilities offered by the high-resolution spectrograph UVES on ESO’s Very Large Telescope, have found a metal-rich hydrogen cloud in the distant universe. The result may help to solve the missing metal problem and provides insight on how galaxies form.
“Our discovery shows that significant quantities of metals are to be found in very remote galaxies that are too faint to be directly seen”, said C??bf?line P??bf?roux (ESO), lead-author of the paper presenting the results.
The astronomers studied the light emitted by a quasar located 9 billion light-years away that is partially absorbed by an otherwise invisible galaxy sitting 6.3 billion light-years away along the line of sight.
The analysis of the spectrum shows that this galaxy has four times more metals than the Sun. This is the first time one finds such a large amount of ‘metals’ in a very distant object. The observations also indicate that the galaxy must be very dusty.
Almost all of the elements present in the Universe were formed in stars, which themselves are members of galaxies. By estimating how many stars formed over the history of the Universe, it is possible to estimate how much metals should have been produced. This apparently straightforward reasoning has however since several years been confronted with an apparent contradiction: adding up the amount of metals observable today in distant astronomical objects falls short of the predicted value. When the contribution of galaxies now observed at cosmological distances is added to that of the intergalactic medium, the total amounts for no more than a tenth of the metals expected.
Studying distant galaxies is however a difficult task. The further a galaxy, the fainter it is, and the small or intrinsically faint ones won’t be observed. This may introduce severe biases in the observations as only the largest and most active galaxies are picked up.
Astronomers therefore came up with other ways to study distant galaxies: they use quasars, most probably the brightest distant objects known, as beacons in the Universe.
Interstellar clouds of gas in galaxies, located between the quasars and us on the same line of sight, absorb parts of the light emitted by the quasars. The resulting spectrum consequently presents dark ‘valleys’ that can be attributed to well-known elements. Thus, astronomers can measure the amount of metals present in these galaxies – that are in effect invisible – at various epochs.
“This can best be done by high-resolution spectrographs on the largest telescopes, such as the Ultra-violet and Visible Echelle Spectrograph (UVES) on ESO’s Kueyen 8.2-m telescope at the Paranal Observatory,” declared P??bf?roux.
Her team studied in detail the spectrum of the quasar SDSS J1323-0021 that shows clear indications of absorption by a cloud of hydrogen and metals located between the quasar and us. From a careful analysis of the spectrum, the astronomers found this ‘system’ to be four times richer in zinc than the Sun. Other metals such as iron appear to have condensed into dust grains.
“If a large number of such ‘invisible’ galaxies with high metal content were to be discovered, they might well alleviate considerably the missing metals problem”, said Peroux.
Original Source: ESO News Release | 0.845586 | 4.107042 |
No, not that kind of snow, but scientists say deep inside the planet Mercury, iron “snow†forms and falls toward the center of the planet, much like snowflakes form in Earth’s atmosphere and fall to the ground. The movement of this iron snow could be responsible for Mercury’s mysterious magnetic field, and Mercury may be the only body in our solar system where this occurs.
Mercury and Earth are the only local terrestrial planets that possess a global magnetic field. But Mercury’s is about 100 times weaker than Earth’s, which scientists have been unable to explain.
Made mostly of iron, Mercury’s core is also thought to contain sulfur, which lowers the melting point of iron and plays an important role in producing the planet’s magnetic field.
To better understand the physical state of Mercury’s core, the researchers in a lab recreated the conditions believed to exist at Mercury’s core, and melted an iron-sulfur mixture at high pressures and high temperatures.
In each experiment, an iron-sulfur sample was compressed to a specific pressure and heated to a specific temperature. The sample was then quenched, cut in two, and analyzed with a scanning electron microscope and an electron probe microanalyzer.
As the molten, iron-sulfur mixture in the outer core slowly cools, iron atoms condense into cubic “flakes†that fall toward the planet’s center, said Bin Chen, University of Illinois graduate student and lead author of a paper published in the April issue of Geophysical Research Letters. As the iron snow sinks and the lighter, sulfur-rich liquid rises, convection currents are created that power the dynamo and produce the planet’s weak magnetic field.
The researchers say their findings provide a new context for the data that will be obtained from NASA’s MESSENGER spacecraft, which will flyby Mercury for a second time on October 6, 2008. It will pass by the planet again in September of 2009, and go into orbit in March of 2011.
Original News Source: Eureka Alert
Here are some interesting facts about Mercury. | 0.837332 | 3.12445 |
“1… 2… 3… 4…”
The counting in the Hayabusa2 control room at the Japan Aerospace Exploration Agency’s Institute of Space and Astronautical Sciences (JAXA, ISAS) took on a rhythmic beat as everyone in the room took up the chant, their eyes fixed on the large display mounted on one wall.
“10… 11… 12… 13…”
The display showed the line-of-sight velocity (speed away from or towards the Earth) of the Hayabusa2 spacecraft. The spacecraft was about 240,000,000 km from the Earth where it was studying a near-Earth asteroid known as Ryugu. At this moment, the spacecraft was dropping to the asteroid surface to collect a sample of the rocky body.
“20… 21… 22… 23…”
Asteroid Ryugu is a carbonaceous or “C-type” asteroid; a class of small celestial bodies thought to contain organic material and undergone relatively little alteration since the beginning of the Solar System. Rocks similar to Ryugu would have pelted the early Earth, possibly delivering both water and the first ingredients for life to our young planet. Where and when these asteroids formed and how they moved through the Solar System is therefore a question of paramount importance to understanding how terrestrial planets like the Earth became habitable. It is a question not only tied to our own existence, but also to assessing the prospect of life elsewhere in the Universe.
The Hayabusa2 mission arrived at asteroid Ryugu just over one year ago at the end of June 2018. The spacecraft remotely analyzed the asteroid and deployed two rovers and a lander to explore the surface. Then in February of this year, the spacecraft performed its own descent to touchdown and collect a sample. The material gathered will be analyzed back on Earth when the spacecraft returns home at the end of 2020.
Touchdown is one of the most dangerous operation in the mission. The distances involved mean that it took about 19 minutes to communicate with the spacecraft during the first touchdown and 13 minutes during the second touchdown, when the asteroid had moved slightly closer to Earth. Both these durations are too long to manually guide the spacecraft to the asteroid surface.… Read more | 0.849096 | 3.117508 |
A white dwarf surrounded by a cocoon of gas
Click on image for full size
When stars like our own sun die they will become white dwarfs. As a star like our sun is running out of fuel in its core it begins to bloat into a red giant
. This will happen to our sun in 5 Billion years. The inner planets, Mercury, Venus, Earth, and Mars will all be consumed by the sun's expanding surface. Then after a few million years the outer layers of the red giant will begin to puff off and form a planetary nebula. Leaving behind only the dead core of the star made of mostly carbon and oxygen. This is the white dwarf.
A typical white dwarf is about the size of the Earth. It is also very dense and hot. A spoonful of white dwarf material on Earth would weigh as much as a car. Strange, isn't it?
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“The universe is under no obligation to make sense to you.” (Neil DeGrasse Tyson)
However, as humans we cannot help but marvel at the great infinite sky and the sheer number of stars and constellations. We can trace first cave drawings of stars as far back as the stone age and we owe much of our star maps and constellation names to the Greeks and Romans. We have been looking at the night sky for our fortunes, to navigate and to share our ancestors’ stories and traditions.
Yesterday’s May Day, also known as the festival of Beltane, signifies the move away from the darker season towards the outdoors. It is one of the midway four-quarter days between an equinox and solstice, in this case, the March equinox and June solstice.
On International Astronomy Day, 2 May 2020, we want to take a wee look at some of the lore and symbolism around the constellation of Taurus. Today’s reduction in air travel and light pollution allows for slightly clearer night skies if we ignore the satellite pollution from SpaceX Starlinks’ satellites. Let us take a quick look at the stars and maybe Taurus, the bull, will give you a nudge do some star gazing from your window or in your backyard.
Taurus the bull
Taurus is one of the twelve constellations of the zodiac, associated with the astrological sign of the same name, assigned to the period from 21 April to 21 May. Traditionally, Taurus is displayed head-on, with only his front legs and chest facing the viewer.
The constellation dates back as far as the Sumerians around 3000BC, when the bull was considered a powerful symbol of fertility, signalling a time of rebirth and the start of spring. Later the Greek thought of it as the bull Zeus transformed into, so he could win Europa’s affections by carrying her off to Crete.
Taurus is home to two prominent star clusters: the Pleiades and the Hyades. According to legend, the Hyades were the five daughters of Atlas — the titan of ancient Greek myth who carried the world on his shoulders — and half-sisters to the Pleiades.
The Pleiades were called the “seed stars” by the Zuni, because when they disappeared into the western dusk in spring, they knew it was safe to plant their seeds and the time of frost had passed.
Fun fact: star clusters were sometimes used as an eye test in ancient times! In the stories about the Pleiades, one of the seven sisters is always missing. This is easily correlated with the real sky, as most people will only see 6 stars with the unaided eye. If you could see all the seven stars of the Pleiades, you were thought to have excellent vision.
In darkness we seek light and we hope that you will find some time to enjoy Astronomy Day, and maybe look up constellations and share stories about the stars.
For some further reading inspiration around astronomy and starlore take a look below:
Sky Stories Ancient and Modern (New York: 1998) Roger Ptak
What We See in the Stars (Boxtree, 2017) Kelsey Oseid
Astrophysics for People in a Hurry (Norton & Company 2017) Neil DeGrasse Tyson | 0.849519 | 3.333787 |
Reading time ( words)
Robots can drive on the plains and craters of Mars, but what if we could explore cliffs, polar caps and other hard-to-reach places on the Red Planet and beyond? Designed by engineers at NASA's Jet Propulsion Laboratory in Pasadena, California, a four-limbed robot named LEMUR (Limbed Excursion Mechanical Utility Robot) can scale rock walls, gripping with hundreds of tiny fishhooks in each of its 16 fingers and using artificial intelligence (AI) to find its way around obstacles. In its last field test in Death Valley, California, in early 2019, LEMUR chose a route up a cliff while scanning the rock for ancient fossils from the sea that once filled the area.
LEMUR was originally conceived as a repair robot for the International Space Station. Although the project has since concluded, it helped lead to a new generation of walking, climbing and crawling robots. In future missions to Mars or icy moons, robots with AI and climbing technology derived from LEMUR could aid in the search for similar signs of life. Those robots are being developed now, honing technology that may one day be part of future missions to distant worlds. Here are five in the works:
A Mechanical Worm for Icy Worlds
How does a robot navigate a slippery, icy surface? For Ice Worm, the answer is one inch at a time. Adapted from a single limb of LEMUR, Ice Worm moves by scrunching and extending its joints like an inchworm. The robot climbs ice walls by drilling one end at a time into the hard surface. It can use the same technique to stabilize itself while taking scientific samples, even on a precipice. The robot also has LEMUR's AI, enabling it to navigate by learning from past mistakes. To hone its technical skills, JPL project lead Aaron Parness tests Ice Worm on glaciers in Antarctica and ice caves on Mount St. Helens so that it can one day contribute to science on Earth and more distant worlds: Ice Worm is part of a generation of projects being developed to explore the icy moons of Saturn and Jupiter, which may have oceans under their frozen crusts.
A Robotic Ape on the Tundra
Ice Worm isn't the only approach being developed for icy worlds like Saturn's moon Enceladus, where geysers at the south pole blast liquid into space. A rover in this unpredictable world would need to be able to move on ice and silty, crumbling ground. RoboSimian is being developed to meet that challenge.
Originally built as a disaster-relief robot for the Defense Advanced Research Projects Agency (DARPA), it has been modified to move in icy environments. Nicknamed "King Louie" after the character in "The Jungle Book," RoboSimian can walk on four legs, crawl, move like an inchworm and slide on its belly like a penguin. It has the same four limbs as LEMUR, but JPL engineers replaced its gripping feet with springy wheels made from music wire (the kind of wire found in a piano). Flexible wheels help King Louie roll over uneven ground, which would be essential in a place like Enceladus.
Micro-climbers are wheeled vehicles small enough to fit in a coat pocket but strong enough to scale walls and survive falls up to 9 feet (3 meters). Developed by JPL for the military, some micro-climbers use LEMUR's fishhook grippers to cling to rough surfaces, like boulders and cave walls. Others can scale smooth surfaces, using technology inspired by a gecko's sticky feet. The gecko adhesive, like the lizard it's named for, relies on microscopic angled hairs that generate van der Waals forces — atomic forces that cause "stickiness" if both objects are in close proximity.
Enhancing this gecko-like stickiness, the robots' hybrid wheels also use an electrical charge to cling to walls (the same phenomenon makes your hair stick to a balloon after you rub it on your head). JPL engineers created the gecko adhesive for the first generation of LEMUR, using van der Waals forces to help it cling to metal walls, even in zero gravity. Micro-climbers with this adhesive or gripping technology could repair future spacecraft or explore hard-to-reach spots on the Moon, Mars and beyond.
Ocean to Asteroid Grippers
Just as astronauts train underwater for spacewalks, technology built for ocean exploration can be a good prototype for missions to places with nearly zero gravity. The Underwater Gripper is one of the gripping hands from LEMUR, with the same 16 fingers and 250 fishhooks for grasping irregular surfaces. It could one day be sent for operations on an asteroid or other small body in the solar system. For now, it's attached to the underwater research vessel Nautilus operated by the Ocean Exploration Trust off the coast of Hawaii, where it helps take deep ocean samples from more than a mile below the surface.
A Cliff-Climbing Mini-Helicopter
The small, solar-powered helicopter accompanying NASA's Mars 2020 rover will fly in short bursts as a technology demonstration, paving the way for future flying missions at the Red Planet. But JPL engineer Arash Kalantari isn't content to simply fly; he's developing a concept for a gripper that could allow a flying robot to cling to Martian cliffsides. The perching mechanism is adapted from LEMUR's design: It has clawed feet with embedded fishhooks that grip rock much like a bird clings to a branch. While there, the robot would recharge its batteries via solar panels, giving it the freedom to roam and search for evidence of life. | 0.857901 | 3.105886 |
The VST surveys
The primary function of the VST is to support the Very Large Telescope by providing surveys — both extensive, multi-colour imaging surveys and more specific searches for rare astronomical objects. Three of these surveys are well advanced as part of the Public Surveys Project, and they are anticipated to take five years to carry out. These are the Kilo-Degree Survey (KIDS), VST ATLAS and the VST Photometric Hα Survey of the Southern Galactic Plane (VPHAS+). They are focusing on a wide range of astronomical issues from searching for highly energetic quasars to understanding the nature of dark energy.
KIDS — The Kilo-Degree Survey
This survey is imaging 1500 square degrees in four bands (U, V, R and I). The data collected is complemented by near-infrared observations from the VISTA Kilo-Degree Infrared Galaxy survey (VIKING). The combined data covers nine bands from optical to infrared. The large area the survey covers is to be imaged to a depth deeper than the Sloan Digital Sky Survey (SDSS) by 2.5 magnitudes, and with superior quality. KIDS science goals include studying dark matter halos and dark energy with weak lensing, hunting for high-redshift quasars and galaxy clusters, and studying galactic evolution.
The VST ATLAS
This survey is targeting 4500 square degrees of the Southern sky in five filters (U, V, R, I and Z) to depths comparable to those of the SDSS. This survey is also complemented by near-infrared data from the VISTA Hemisphere Survey. The primary aim is to examine ‘baryon wiggles’ (small-amplitude oscillations observed in the power spectrum of galaxies) by looking at luminous red galaxies in order to determine the dark energy equation of state. Along with this, the VST ATLAS will provide an imaging base for spectroscopic surveys by the VLT.
VPHAS+ — The VST Photometric H-alpha Survey of the Southern Galactic Plane
This survey is covering 1800 square degrees using five bands (U, V, Ha, R and I), covering a considerable part of the Southern Galactic Plane. VPHAS is studying around 500 million objects including many rare star types such as Be and T-Tauri stars. The survey can also be used to map the structure of the Galactic disc and to understand the star-formation history of the Milky Way.
In addition to the three public surveys, a set of projects is being carried out under the guaranteed observing time agreement between ESO and Capodimonte Astronomical Observatory. More information can be found at the VLT Survey Telescope Center at Naples Web Portal. | 0.870262 | 3.853618 |
X-ray emission from Warm-Hot Intergalactic Medium
The Warm-Hot Intergalactic Medium contributes substantially to the matter budget in the Universe – but it is only poorly studied, as it is very difficult to observe. Researchers at MPA have now predicted how it can be explored using heavier elements as tracers. Due to scattering of the cosmic X-ray background some of this line emission can be boosted substantially and should be accessible by the upcoming X-ray survey missions.
Half of the baryonic budget in the present-day Universe is very well hidden – astronomers believe it can be found in the Warm-Hot Intergalactic Medium, which is as abundant and imperceptible as the nitrogen in the air we breathe. Being produced naturally by the ongoing formation of the largest structures in the Universe, this gas has a temperature between 100,000 and 1 million Kelvin and its density exceeds the mean baryonic density by less than a factor of 100. The high temperature of this gas implies that hydrogen and helium should be almost fully ionized and, as a consequence, it cannot be revealed via the Lyman alpha absorption features in the spectra of background quasars (contrary to the high-redshift intergalactic medium, which is readily detected in this way). It is also difficult to observe this gas directly, since its thermal emission is very faint (due to its low density) and also happens to peak in the observationally-challenging extreme UV/soft X-ray energy range.
Fortunately, the Warm-Hot Intergalactic Medium is enriched by heavier elements (such as carbon, nitrogen, oxygen, neon and iron) expelled from the star-forming galaxies by powerful galactic-scale outflows (as hinted e.g. by cosmological hydro-simulations, see Fig.1). Having escaped full ionization, atoms of heavy elements produce numerous emission lines and resonant absorption features. For a low density gas, such as the Warm-Hot Intergalactic Medium, the absorption features are particularly important, since their amplitude is proportional to the total number of ions on the line-of-sight, so it scales linearly with the gas number density. While a large amount of observing time has already been invested in searches for the Warm-Hot Intergalactic Medium by this technique (taking advantage of high resolution grating spectrometers on board the Chandra and XMM-Newton X-ray observatories), only marginal detections have been reported so far.
In fact, these absorption features are a result of resonant scattering, which is not a true absorption process by itself. Indeed, the intensity lost in the direction of the bright background sources is compensated by increased intensity in all other directions (see Fig. 2). The net effect of course cancels out after integrating over all directions in the case of an isotropic radiation field, such as the Cosmic X-ray Background. Nonetheless, a large portion of this background is contributed by bright individual sources (mainly Active Galactic Nuclei), which can be resolved and excluded from a given aperture. The remaining signal will then contain both the unresolved part of the background radiation (with similar absorption features as in resolved part) plus the spatially-extended resonantly-scattered background radiation. This emission is heavily dominated by the brightest resonance lines and supplements the intrinsic thermal emission from a slab of Warm-Hot Intergalactic Medium, boosting its overall X-ray emissivity and changing important spectral characteristics such as the equivalent widths of the lines and their respective ratios.
Recently, MPA scientists performed calculations of the X-ray emission from a layer of Warm-Hot Intergalactic Medium that take into account photoionization by the Cosmic X-ray Background and allow self-consistent inclusion of the resonantly scattered line emission (see Fig.3). The overall boost of emission in the most prominent resonant lines (O VII, O VIII and Ne IX) was found to equal ~30, and this boost is pretty much uniform across almost the whole region of the density-temperature diagram relevant for the Warm-Hot Intergalactic Medium. Even after averaging over broader spectral bands, the boost factor remains very significant (~5) but declines steeply at temperatures above T~1 million K (for all considered densities) and at over-densities > 100, as demonstrated in Fig.4 for the 0.5-1 keV band. The predicted total emission in this band is predicted to be dominated by the resonant lines of the helium- and hydrogen-like oxygen, which have comparable intensity for the major part of the explored parameter space.
A significant detection of a layer of Warm-Hot Intergalactic Medium (at a redshift ~0.1) in emission might be achieved by an X-ray instrument with an effective area of about 1000 cm^2 (at 0.5-1 keV) with a exposure on the order of 1 million seconds over one square degree of the sky – taking into account contamination by the unresolved cosmic X-ray background and the Galactic diffuse soft X-ray foreground. These requirements might already be met with a single observation by the eROSITA telescope onboard of the forthcoming SRG mission.
Future X-ray missions will indeed provide great opportunities to study the Warm-Hot Intergalactic Medium, both with large-area X-ray surveys and with deep small-area observations with X-ray calorimeters. For the former, the signal can be detected by a cross-correlation of the stacked (absorption and emission) X-ray signal with certain tracers of overdensities in the large-scale structure (e.g. 2MASS galaxies), while for the latter detection (and potentially diagnostics) of prominent individual filaments at z~0.1 is the primary goal. | 0.878574 | 4.161451 |
We have a wide variety of programs suited for Grades 3 and up. Our most popular programs include:
CONSTELLATIONS & MYTHOLOGY: (Grades 4 and up)
What constellations are in the sky in the early evening? Do you look up and feel lost amongst a myriad of stars? Many cultures in the past made up stories about the stars to give their people a better understanding of what was out there. Today, we have science to tell us. This class will introduce you to the constellations and mythology of the night time sky, as well as provide some science background about the stars. This class is generally taught in conjunction with the Starlab class (see below) but can be done in a regular classroom setting.
LUNAR CRATERS: (Grades 4 and up)
Have you ever looked closely at the Moon's surface and seen how heavily cratered it is? How did those craters form? This class will introduce you to the dynamics of cratering and what the future may hold for us in terms of impacts on our world.
MODEL OF THE SOLAR SYSTEM: The immense sizes and distances of our nearest neighbors in space have managed to confound even adults. Now, using the Science Center's own visible scale model of the solar system, your students will gain an appreciation for its awesome dimensions. This activity is best presented at the Science Center, but can be adapted for your classroom.
PHASES OF THE MOON: (Grades 3 and up)
Why does the Moon cycle through its monthly phases? How does it move around the Earth? This class will introduce you to the motions of the Moon through the celestial sphere, as well as the phases seen from the Earth. Students will also model the Earth-Moon-Sun system to demonstrate the phases as well as lunar and solar eclipses, and the distance that the Moon is from the Earth.
SOLAR OBSERVING: (Grades 4 and up)
The only star where we can see surface detail is the Sun, and now is a great time to observe the Sun, as we are near a maximum of the solar activity cycle. This class will introduce you to safe solar viewing and the implications involved with an active Sun. Learn about the solar wind and how it affects the near Earth environment.
SUN, MOON & EARTH FIELD TRIP: The Sun, Moon and Earth field trip consists of two hours, divided into three 40 minute activities conducted at Talcott Mountain. The activities focus the theme of Sun, Moon and Earth and their relative motions. Students become familiar with these concepts from direct observation and simulation both in the Capt. Alan Bean Hypospherium and from our observation deck on top of the ridge. From the ridge students can observe the largest visible model of the solar system and compare this to landmarks they can recognize. An option to construct sundials in case of bad weather will be offered as an alternative activity. Students will learn how telescopes work and use them to observe the moon in the daytime or familiar objects from our high vantage point.
SUNDIALS: This classic interdisciplinary activity weaves history, culture, and astronomy with observation and critical thinking to allow students to discover the oldest known method of timekeeping. Each student will build a simple sundial, then use it outdoors (weather permitting) to tell the time of day. On cloudy days, the passage of time may be simulated in the classroom so students will see their sundials at work.
Other programs that are available:
ASTROPHOTOGRAPHY: (Grades 6 and up)
Do you want to take images of the planets and the stars? Astrophotography is really not all that difficult, it just takes a little patience and creativity. This class will introduce you to the ins and outs of astrophotography, from the basics to the advanced concepts. Since this class requires special equipment, it is necessary to come to the Science Center for this class.
GALAXIES: (Grades 6 and up)
What is a galaxy? How do they form? Why are there different types? How far away is the most distant galaxy? These questions and more will be addressed as you learn about the nature of galaxies and their distribution throughout the Universe. Students will also try their hand at galaxy identification using Hubble's Tuning Fork Diagram.
LIGHT: (Grades 5 and up)
Of all the sciences, Astronomy is the most hands-off science of them all. If technology permitted we could travel to distant planets and stars and witness firsthand the beauty of them all. Instead, earth-bound astronomers have to study the only thing which arrives here from those distant and exotic locales - light. The study of light and how it behaves is crucial to the science of Astronomy. This class will introduce you to the many forms of light, from high energy gamma rays to the low energy radio waves and how these other forms of light provide us with new insights into the nature of the Universe.
NIGHTTIME OBSERVING: (Grades 4 and up)
After several classes with the Science Center at your school, how about wrapping up your unit on Astronomy with a nighttime visit to the Science Center for a night of observing the heavens? Explore the wonders of the night sky through many telescopes. Observe planets, stars, galaxies, and nebulae. This class will also use the Captain Alan Bean Hypospherium, Connecticut's largest planetarium to familiarize everyone with the night sky. Since this class is weather dependent, a rain/cloud date should be considered.
ROCKETRY: (Grades 4 and up)
What better way to introduce a unit on space and astronomy than a class in rocketry? Students will learn about the history and physics of rocket flight and construct a rocket for launch. This class generally consists of at least two (and sometimes three) sessions, each 1.5 hours in length; (1) history/construction and (2) launch.
SPECTRAL ANALYSIS: (Grades 7 and up)
This class probes more deeply into the properties of light and spectral analysis. Students will study stellar spectra and how they relate to the spectral sequence for stars. Analysis of stellar evolution and the Hertzsprung-Russell diagram will also be included.
STELLAR EVOLUTION: (Grades 4 and up)
How did our Sun come to be? What is the eventual fate of our Sun and the others that we see in the sky at night? Stellar evolution is one of the most fascinating subjects in Astronomy, covering the births and deaths of the stars. This class will introduce you to young protostars, middle-aged main sequence stars, red giants, white dwarfs, neutron stars, pulsars, and black holes.
THE BEGINNING & END OF THE UNIVERSE: (Grades 6 and up)
How did the Universe originate and what is it's eventual fate? Do we live in an open or closed universe? These questions are some of the most profound that astronomers ask. This class seeks to answer some of these questions through an introduction to the Big Bang, evolution of the Universe, and what lies in the future. | 0.880198 | 3.020113 |
Figure 1. CFHT color image, taken in g,r, and i filters, of J2240. The very strong [OIII] emission leads to the peculiar green color of the galaxy near the center of the field. In this object the ultra-luminous narrow-line region (NLR) is as large as the entire object, 130,000 light-years across. The object is located some 3.7 billion light-years distant and the galactic nucleus doesn’t appear very active in the image, contradicting the high [OIII] luminosity discussed in this story.
Figure 2. [OIII] emission versus the mid-IR luminosity as measured by the WISE satellite. The [OIII] fluxes of the objects discovered (asterisks) are 5-50 times higher than expected when compared to normal quasars at the same redshift range (black dots). This is direct evidence that the nuclear activity has substantially decreased, and the NLR still reflects an earlier, much more active state.
December 5, 2012
Using joint observations from Gemini South, the European Southern Observatory’s Very Large Telescope (ESO/VLT), and the Canada-France-Hawaii Telescope (CFHT), a team of astronomers has discovered a spectacular and very rare phenomenon in galaxies. It is interpreted as a light echo from an earlier, very active, quasar phase that has since shut down. Because of these objects' unique characteristics, they appear green in some datasets giving them the colorful moniker “green-bean galaxies.”
As described in the ESO press release today (December 5, 2012), Gemini astronomer Mischa Schirmer first identified an example of this odd class of object in CFHT imaging data –– a distant galaxy denoted J224024.1−092748 or J2240 (Figure 1).
After investigating the new object with the VLT, and confirming it with Gemini South, Schirmer and his team went on to observe several additional candidates with the Gemini telescope. These spectroscopic observations confirmed that another 16 candidates share the same characteristics as J2240, and Schirmer verified their cosmological distances with the Gemini data. These galaxies are exceedingly rare. Only one such galaxy is expected in a square cube with sides 1.3 billion light-years across.
Quasar light echoes have been known for a few years, but only within our nearer cosmic neighborhood and with much lower luminosity. The 16 new, high-luminosity, objects now identified with Gemini-South will allow astronomers, for the first time, to directly determine how individual quasars have shut down over timescales much longer than a human lifetime. These results open up a new window in the study of how supermassive black holes in the cores of galaxies might have gained their mass, and how quickly that process can come to a halt.
These results open up a new window in the study of how supermassive black holes in the cores of galaxies might have gained their mass, and how quickly that process can come to a halt.
The team’s work on J2240 has been accepted for publication in the Astrophysical Journal, can be found on arXiv here.
Supplemental and Background Information
One of the most significant astronomical discoveries in the last decade is the realization that almost every massive galaxy harbors a supermassive black hole (SMBH) at its center. SMBHs gain millions to billions times the mass of the Sun by accreting material from their immediate surroundings. The matter is forced into a rotating accretion disk around the black hole. As the matter spirals down onto the black hole, it reaches temperatures of millions of degrees, generating large amounts of X-rays in the process. The intensity of these X-rays tells us how active a SMBH currently is. Part of the X-ray radiation is absorbed by dust in the immediate vicinity of the black hole. Consequently, the dust heats up and re-emits the energy absorbed at thermal mid-infrared wavelengths, from which astronomers can also infer the SMBH's current activity level. The most active of these galaxies are known as quasars.
The remainder of the X-ray radiation escaping from the galactic centers ionizes the interstellar gas in the host galaxies. This can be seen in the galaxies' spectra by extended emission of double ionized oxygen, [OIII]. Usually, these so-called narrow-line regions (NLRs) have an extent of 1000-10,000 light-years, i.e. 1-10 percent of the diameter of a typical galaxy. Their luminosity correlates well with the X-ray luminosity of the SMBHs. Today, the centers of most galaxies are largely quiescent, but the presence of a SMBH shows that in their past they must have undergone a very active phase.
In this new class of “green-bean galaxies,” [OIII] luminosities rival those of the brightest quasars known but astronomers haven’t observed a quasar at the centers of these galaxies. Therefore, either the quasars radiation is absorbed by large amounts of dust, or they have been shutting down in the very recent past –– so recent, in fact, that the lower X-ray flux hasn't yet reached the farther regions of the NLR. In the latter scenario one would observe a light echo, in which the ionized gas further from the nucleus still reflects the earlier, more active quasar state.
Since mid-infrared photons aren’t affected by dust obscuration it reveals that the [OIII] emission in these galaxies is indeed 5-50 times higher than expected, confirming the light echo. While active galaxies are known to change their luminosity on hours to decades timescales, and by 10 percent up to a factor of 10, respectively, time scales longer than about two decades have not been studied previously. Accretion models predict that the luminosity of the central SMBH engine can drop by factors of 10,000 over some 100,000 years.
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The GEMMA Podcast
A podcast about Gemini Observatory and its role in the Era of Multi-Messenger Astronomy. Featuring news related to multi-messenger astronomy (MMA), time-domain astronomy (TDA), our visiting instrument program, and more through interviews with astronomers, engineers, and staff both here at Gemini (North and South) and abroad. | 0.921345 | 4.002045 |
Using the Microwave Instrument for the Rosetta Orbiter (MIRO), scientists have studied the comet’s southern polar regions at the end of their long winter season. The data suggest that these dark, cold regions host ice within the first few tens of centimetres below the surface in much larger amounts than elsewhere on the comet.
Since its arrival at Comet 67P/Churyumov-Gerasimenko, Rosetta has been surveying the surface and the environment of this curiously-shaped body. But for a long time, a portion of the nucleus – the dark, cold regions around the comet’s south pole – remained inaccessible to almost all instruments on the spacecraft.
Due to a combination of its double-lobed shape and the inclination of its rotation axis, Rosetta’s comet has a very peculiar seasonal pattern over its 6.5 year-long orbit. Seasons are distributed very unevenly between the two hemispheres, each of which comprises parts of both comet lobes and of the ‘neck’.
For most of the comet’s orbit, the northern hemisphere experiences a very long summer, lasting over 5.5 years, and the southern hemisphere undergoes a long, dark and cold winter. However, a few months before the comet reaches perihelion – the closest point to the Sun along its orbit – the situation changes, and the southern hemisphere transitions to a brief and very hot summer.
When Rosetta arrived at 67P/C-G in August 2014, the comet was still experiencing its long summer in the northern hemisphere and regions on the southern hemisphere received very little sunlight. Moreover, a large part of this hemisphere, close to the comet’s south pole, was in polar night and had been in total darkness for almost five years.
With no direct illumination from the Sun, these regions could not be imaged with Rosetta’s OSIRIS science camera. In addition, their low temperatures – ranging between 25 and 50 degrees above absolute zero – did not allow observations with VIRTIS, the Visible, InfraRed and Thermal Imaging Spectrometer, either.
For the first several months after Rosetta’s arrival at the comet, only one instrument on the spacecraft could observe and characterise the cold southern pole of 67P/C-G: the Microwave Instrument for the Rosetta Orbiter (MIRO).
In a paper accepted for publication in the journal Astronomy and Astrophysics, scientists report on the data collected by MIRO over these regions between August and October 2014.
“We observed the ‘dark side’ of the comet with MIRO on many occasions after Rosetta’s arrival at 67P/C-G, and these unique data are telling us something very intriguing about the material just below its surface,” explains Mathieu Choukroun from NASA’s Jet Propulsion Laboratory, lead author of the study.
Observing the comet’s southern polar regions, Choukroun and colleagues found significant differences between the data collected with MIRO’s millimetre and sub-millimetre wavelength channels. These differences might point to the presence of large amounts of ice within the first few tens of centimetres below the surface of these regions.
“Surprisingly, the thermal and electrical properties around the comet’s south pole are quite different to what is found elsewhere on the nucleus. It appears that either the surface material or the material that lies down to a few tens of centimetres below it is extremely transparent at the MIRO wavelengths of 0.5 and 1.6 mm, and could consist mostly of water ice or carbon-dioxide ice,” he adds.
The difference between the surface and sub-surface composition of this part of the nucleus and that found elsewhere might originate in the comet’s peculiar cycle of seasons. One of the possible explanations is that water and other gases that were released during the comet’s previous perihelion, when the southern hemisphere was the most illuminated portion of the nucleus, condensed again and precipitated on the surface after the season changed and the southern hemisphere plunged again into its long and cold winter.
These are, however, preliminary results, because the analysis depends on the detailed shape of the nucleus, and at the time the measurements were made the shape of the dark, southern polar region was not known to great accuracy.
“We plan to revisit the MIRO data using an updated version of the digital shape model, to verify these early results and refine the interpretation of the measurements,” adds Choukroun.
Besides, Rosetta scientists will be testing these and other possible scenarios using data that were collected in the subsequent months, leading to the comet’s perihelion, which took place on 13 August 2015, and beyond.
In May 2015, the seasons changed on 67P/C-G and the brief, hot southern summer, which will last until early 2016, began. As the formerly dark southern polar regions started to receive more sunlight, it has been possible to observe them with other instruments on Rosetta, and the combination of all data might eventually disclose the origin of their curious composition.
“In the past few months, Rosetta has flown over the southern polar regions on several occasions, starting to collect data from this part of the comet after summer began there,” explains Matt Taylor, ESA Rosetta project scientist.
“At the beginning of the southern summer, we had a paucity of observations in these regions as Rosetta’s trajectory focussed on the northern hemisphere due to ongoing communication with the lander, Philae. However, closer to perihelion we were able to begin observing the south.
“Rosetta is currently on an excursion out to 1500 km from the nucleus to study the comet’s environment at large, but it will soon come closer to the comet, focussing on full orbits to compare the northern and southern hemispheres, as well as some slower passes in the south to maximise our observations there. In addition, as activity will start to wane later this year, we hope to get closer to the nucleus and gain higher resolution observations of the surface.”
Mark Hofstadter, MIRO Principal Investigator at NASA’s Jet Propulsion Laboratory, describes the result as “a great example of how the scientific process unfolds as Rosetta is studying the evolution of this comet up close.”
“First, we observed these dark regions with MIRO, the only instrument able to do so at the time, and we tried to interpret these unique data. Now, as these regions became warmer and brighter around perihelion, we can observe them with other instruments, too,” he adds.
“We hope that, by combining data from all these instruments, we will be able to confirm whether or not the south pole had a different composition and whether or not it is changing seasonally.”
This blog post is based on the paper “The “Dark Side” of 67P/Churyumov-Gerasimenko in Aug-Oct 2014 – MIRO/Rosetta continuum observations of polar night in the Southern regions,” by M. Choukroun et al, which is accepted for publication in Astronomy and Astrophysics.
Science results from MIRO and other instruments on Rosetta are being presented this week at the European Planetary Science Congress in Nantes, France. | 0.838526 | 4.006925 |
A team of researchers has published the results of an extensive investigation into Supernova 1987A’s violent death, which was witnessed by astronomers in 1987.
They used the Atacama Large Millimeter/Submillimeter Array (ALMA) Telescope in Chile as well as the Telescope Compact Array (ATCA) in Australia to obtain a complete picture of the events.
“By combining observations from the two telescopes we’ve been able to distinguish radiation being emitted by the supernova’s expanding shock wave from the radiation caused by dust forming in the inner regions of the remnant,”
lead author Giovanna Zanardo of the International Centre for Radio Astronomy Research in Perth said.
Scientists attempted to separate the specific emissions coming from the supernova’s demise while also identifying signs of a new object that may have formed after the collapse of the star’s core. According to Zanardo, data collected with the ATCA and ALMA radio telescopes suggests that something never-before-seen may have formed at the center of what remains of Supernova 1987A. Whether that “something” is a spinning neutron star driven pulsar wind nebula or a pulsar is yet to be determined.
“It’s amazing that only now, with large telescopes like ALMA and the upgraded ATCA, we can peek through the bulk of debris ejected when the star exploded and see what’s hiding underneath,”
Scientists used the ATCA and ALMA telescopes to examine Supernova 1987A’s radio emissions in the infrared end of the spectrum. The supernova is located on the outskirts of Tarantula Nebula, within the Large Magellan Cloud (a neighboring galaxy, approximately 168,000 light-years away from the Milky Way). Its name stems from the first year that light from the supernova reached Earth and could be observed by an astronomer in Chile.
The researchers explain that by adding asymmetry to the study of the explosion, they were able to reproduce essential features from the real supernova, for instance, the persistent one-sidedness o the radio images.
Scientists noted that the left side of the supernova’s shockwave swells more rapidly than its right side, so that more radio emission originates there. This shock wave slams into the supernova’s equatorial ring, making the influence of the left side that much more obvious.
“Our simulation predicts that over time the faster shock will move beyond the ring first. When this happens, the lop-sidedness of radio asymmetry is expected to be reduced and may even swap sides.”
Data obtained with the ALMA and ATCA only confirms previous observations, and as such, scientists are confident that they finally have a handle on the physics of this expanding remnant.
“[Scientists] are beginning to understand the composition of the environment surrounding the supernova – which is a big piece of the puzzle solved in terms of how the remnant of SN1987A formed.” | 0.824793 | 4.066238 |
What is the origin of the famous interstellar object ‘Oumuamua? How was it formed and where did it come from? An article published on April 13 in Nature Astronomy by ZHANG Yun from National Astronomical Observatories of Chinese Academy of Sciences (NAOC) and Douglas N. C. Lin from University of California, Santa Cruz, offers a first comprehensive answer to this mystery, which involves tidal forces like those felt by Earth’s oceans and explains all of the unusual characteristics of this interstellar object.
'Oumuamua was discovered on October 19, 2017, by the Panoramic Survey Telescope and Rapid Response System 1 (Pan-STARRS1) located at Hawaii. As the first known interstellar object to visit our Solar System, 'Oumuamua is absolutely nothing like anything else in the Solar System.Its dry surface, unusually elongated shape and puzzling motion even drove some scientists to wonder if it was an alien probe.
Fig.1: An artist’s impression of 'Oumuamua formation based on ZHANG and Lin’scenario (Image by YU Jingchuan from Beijing Planetarium)
"It is really a mystery," said ZHANG Yun, first author of the study, "but some signs, like its colors and the absence of radio emission, point to ‘Oumuamua being a natural object."
"Our objective is to come up with a comprehensive scenario, based on well understood physical principle to piece together all the tantalizing clues," said Douglas Lin, coauthor of the study.
It was generally assumed that the first discovered interstellar object would be an icy body, like comets. In effect, icy objects are constantly tossed out of their host systems. They are also much more visible due to their apparent coma. However, 'Oumuamua’s dry appearance, similar to rocky bodies, like asteroids in the Solar System, indicates a different ejection scenario.
"The discovery of 'Oumuamua implies that the population of rocky interstellar objects is much larger than we previously thought. On average, each planetary system should eject in total about a hundred trillion objects like 'Oumuamua. We need to construct a very efficient scenario," said ZHANG. "In space, some objects occasionally come very close to a bigger one. Tidal forces of the bigger one can disrupt these small ones, like the things happened to comet Shoemaker-Levy 9 when it closely passed by Jupiter."
ZHANG and Lin ran high-resolution computer simulations to model the dynamics of an object closely flying by a star. They found that the star can dramatically split the object, if it comes enough close to the star, into extremely elongated fragments,and then eject them into the interstellar space.
"The elongated shape is more compelling when we considered the phase transition of material during the stellar encounter. The long-to-short axis ratio can be even larger than ten." ZHANG said. Due to the intense stellar radiation, the surfaces of fragments melt at very short distance to the star and re-condense at further distances. Like melting chocolate beans, the surface materials stick together to maintain the elongated shape.
Fig.2: Illustration of stellar tidal disruption processes (Image by ZHANG Yun)
Fig.3: An 'Oumuamua-like object produced by the scenario proposed by ZHANG and Lin (background by ESO/M. Kornmesser) (Image by ZHANG Yun)
"Heat diffusion also consumes large amounts of volatiles. These fragments become dry and have 'Oumuamua-likesurface." ZHANG added. “However, some water ice buried under the surface can be preserved. These residual water ice could be activated during its Solar System passage to cause its non-gravitational motion."
"The tidal fragmentation scenario not only provides a way to form one single 'Oumuamua, but also accounts for the vast population of rocky interstellar objects." ZHANG said. Their calculations demonstrate the efficiency of stellar tides in producing this kind of objects. Possible progenitors, including long-period comets, debris disks, and even planets, can be transformed into 'Oumuamua-size pieces during stellar encounters. The inferred number density of interstellar objects is consistent with 'Oumuamua’s occurrence rate.
This work highlights the prolificacy of 'Oumuamua-like interstellar object population between stars. Since these objects pass through the domains of habitable zones, the prospect of transport of matter capable of generating life by these objects cannot be ruled out.
"This work provides a plausible narrative that links its strange properties to the process of planet formation that is ubiquitous in the Milky Way Galaxy," said Gregory Laughlin, a professor of astronomy at Yale University.
" 'Oumuamua is just the tip of the iceberg. We anticipate many more interstellar visitors with similar traits will be discovered by future observation with the forthcoming Vera C. Rubin Observatory," Lin said.
"This is a very new field. These interstellar objects could provide critical clues about how planetary systems form and evolve, and how life started on the Earth." ZHANG said.
"This work does a remarkable job of explaining a variety of unusual properties of 'Oumuamua with a single, coherent model," said US Naval Academy astronomer Matthew Knight, co-leader of the 'Oumuamua International Space Science Institute team, "As future interstellar objects are discovered in coming years, it will be very interesting to see if any exhibit ‘Oumuamua-like properties. If so, it may indicate that the processes described in this study are widespread."
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Crescent ♐ Sagittarius
Moon phase on 23 February 2052 Friday is Last Quarter, 22 days old Moon is in Sagittarius.Share this page: twitter facebook linkedin
Last Quarter is the lunar phase on . Seen from Earth, illuminated fraction of the Moon surface is 43% and getting smaller. The 22 days old Moon is in ♐ Sagittarius.
* The exact date and time of this Last Quarter phase is on 22 February 2052 at 18:44 UTC.
Moon rises at midnight and sets at noon. It is visible to the south in the morning.
Moon is passing about ∠12° of ♐ Sagittarius tropical zodiac sector.
Lunar disc appears visually 8.6% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1779" and ∠1939".
Next Full Moon is the Worm Moon of March 2052 after 20 days on 15 March 2052 at 09:54.
There is low ocean tide on this date. Sun and Moon gravitational forces are not aligned, but meet at big angle, so their combined tidal force is weak.
The Moon is 22 days old. Earth's natural satellite is moving through the last part of current synodic month. This is lunation 644 of Meeus index or 1597 from Brown series.
Length of current 644 lunation is 29 days, 13 hours and 6 minutes. It is 2 hours and 15 minutes longer than next lunation 645 length.
Length of current synodic month is 22 minutes longer than the mean length of synodic month, but it is still 6 hours and 41 minutes shorter, compared to 21st century longest.
This lunation true anomaly is ∠285.5°. At the beginning of next synodic month true anomaly will be ∠314.8°. 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°).
2 days after point of apogee on 21 February 2052 at 10:01 in ♏ Scorpio. The lunar orbit is getting closer, while the Moon is moving inward the Earth. It will keep this direction for the next 9 days, until it get to the point of next perigee on 4 March 2052 at 04:33 in ♈ Aries.
Moon is 402 947 km (250 380 mi) away from Earth on this date. Moon moves closer next 9 days until perigee, when Earth-Moon distance will reach 365 498 km (227 110 mi).
4 days after its ascending node on 18 February 2052 at 16:11 in ♎ Libra, the Moon is following the northern part of its orbit for the next 9 days, until it will cross the ecliptic from North to South in descending node on 3 March 2052 at 14:47 in ♈ Aries.
4 days after beginning of current draconic month in ♎ Libra, the Moon is moving from the beginning to the first part of it.
13 days after previous North standstill on 10 February 2052 at 09:08 in ♊ Gemini, when Moon has reached northern declination of ∠18.554°. Next day the lunar orbit moves southward to face South declination of ∠-18.455° in the next southern standstill on 24 February 2052 at 14:50 in ♐ Sagittarius.
After 6 days on 1 March 2052 at 07:36 in ♓ Pisces, the Moon will be in New Moon geocentric conjunction with the Sun and this alignment forms next Sun-Moon-Earth syzygy. | 0.848363 | 3.039366 |
A tiny spacecraft in Earth orbit has successfully deployed its solar sails. Called LightSail 2, the craft will now use the power of the Sun to lift its orbital height even further, in what’s considered an important test of this promising means of propulsion.
LightSail 2 is a crowdfunded project run by the Planetary Society, a nonprofit space organisation. The goal of this proof-of-concept mission is to test the viability of using solar sailing as a means of propelling CubeSats and other objects in space. Eventually, a massively scaled-up version of this technology could take us to the outer realms of the Solar System — and even through interstellar space — at relativistic speeds.
In 2015, the Planetary Society conducted a preliminary test with LightSail 1, but the version currently in space will attempt to use its solar sails to raise its orbit by a measurable amount.
On Wednesday, around four weeks after it was delivered to Earth orbit by a SpaceX Falcon Heavy rocket, LightSail 2 passed its first critical test: the deployment of its solar sails. The Cubesat itself is about the size of a toaster, but with its four triangular, razor-thin sails unfurled, the structure measures 32 square metres in size.
SAIL DEPLOYMENT COMPLETE! We're sailing on SUNLIGHT!!!!! pic.twitter.com/PA74NMa7Ry
— Planetary Society (@exploreplanets) July 23, 2019
The Planetary Society confirmed the successful deployment on its website, saying all of its “major systems are reporting nominally.” Mission controllers for the project are monitoring the spacecraft from their facility in San Luis Obispo, California.
At 2pm Pacific time on July 23, LightSail 2 had entered into solar sailing mode. Its momentum wheel, which works to orient the spacecraft’s position, was operating as expected, while “attitude control system data showed the solar sail was angled to within 30 degrees of its expected orientation — a promising early sign the spacecraft is tracking the Sun properly,” noted the Planetary Society.
The first images of the unfurled sail, taken by the spacecraft itself, were released earlier today in a Planetary Society tweet.
— Planetary Society (@exploreplanets) July 24, 2019
Mission controllers are still evaluating the integrity of the deployment, including a review of the spacecraft’s telemetry data. Assuming everything’s ok, LightSail 2 will start to raise its orbit by harnessing the power of the Sun.
Here’s how it works, according to the Planetary Society:
Light is made of packets of energy called photons. While photons have no mass, they have momentum. Solar sails capture this momentum with sheets of large, reflective material such as Mylar. As photons bounce off the sail, most of their momentum is transferred, pushing the sail forward.
The resulting acceleration is small, but continuous. Unlike chemical rockets that provide short bursts of thrust, solar sails thrust continuously and can reach higher speeds over time. Sunlight is free and unlimited, whereas rocket propellant must be carried into orbit and be stored onboard a spacecraft. Solar sailing is considered one possible means of interstellar space travel.
The Planetary Society is hoping to see LightSail 2 raise its orbit by a measurable amount, which shouldn’t be a problem. The spacecraft is expected to move at a rate of several hundred meters per day. The craft is currently 720 kilometres above the surface of Earth.
In addition to moving small satellites in orbit, large solar sails could conceivably be used to propel heavier spacecraft through the Solar System.
The Breakthrough Starshot project, for example, is envisioning a laser-powered solar sail that could be used for interstellar journeys. Incredibly, these light-propelled “nanocrafts” could travel at speeds approaching 20 per cent the speed of light. At that rate, such a craft could reach our nearest stellar neighbour, Alpha Centauri, in just 20 years.
The Planetary Society is not the first group to experiment with solar sail technology. In 2010, the Japan Aerospace Exploration Agency (JAXA) successfully tested IKAROS, a 196-square-metre solar sail. Unlike LightSail 2, however, IKAROS is an interplanetary traveller, currently making its way through the inner Solar System.
Looking ahead, JAXA is planning to send a 2500-square-metre solar sail to Jupiter’s orbit, where it will study the gas giant’s Trojan asteroids, and then return to Earth. This project is scheduled for launch in the early 2020s.
The era of the solar sail, it would appear, is upon us. | 0.882113 | 3.051401 |
It pays to be smart, and that's very true in the case of the 2015 Breakthrough Prize awards winners. These three winners will share $3 million in prize money for their groundbreaking work probing the physics of our universe.
Physicists Saul Perlmutter, Brian P. Schmidt, and Adam Riess will be splitting a prize of $3 million with the 51 additional researchers who helped make the discovery.
The Breakthrough Prizes doled out a total of $36 million to 11 other science and technology researchers studying mathematics, fundamental physics, and life sciences.
That's nearly three times more than today's Nobel Prize money award, which amounts to $1.2 million — an amount that this year's fundamental physics Breakthrough Prize awardees know very well.
That's because this group of winners are the same astrophysicists who won the 2011 Physics Nobel Prize for discovering that the rate at which our universe is expanding is not slowing down, as many had thought, but speeding up.The Science
Their discovery shook the foundation of cosmology when it was announced in 1998. From everything we think we understand about how gravity works, scientists anticipated that the rate of the expansion of the universe would be slowing down. In fact, it's the exact opposite.
There are a few explanations floating around as to why this is, but the leading one is an enigmatic force called dark energy. Considering how little we know about dark energy, the reason for the accelerating expansion rate of the universe is still shrouded in mystery and is one of the outstanding scientific mysteries of our time. Scientists have since shown that the universe is made of nearly 70% of dark energy.
Throughout the mid-90s two science teams, the Supernova Cosmology Project and the High-z Supernova Search Team, were in a desperate race to measure the universe's expansion. Perlmutter, who is a physics professor at the University of California, Berkeley and astrophysicist at the Lawrence Berkeley National Laboratory, led the Supernova Cosmology Project while Schmidt, who is currently an astrophysicist at The Australian National University Mount Stromlo Observatory, led the High-z Supernova Search Team.
The High-z Supernova Search Team was first to announce their results in 1998, followed shortly by the Supernova Cosmology Project, of which Adam Reiss was a key member. Reiss is an astrophysicist at the Space Telescope Science Institute and professor at Johns Hopkins University.
Both teams separately measured the light from a special kind of stellar explosion called a Type Ia supernova. They used multiple instruments including telescopes at the Cerro Tololo International Observatory and the Hubble Space Telescope. In fact, NASA touts this discovery as the #1 achievement of Hubble.
Based on how they form, every Type Ia supernova emits around the same intensity of light. By measuring that intensity from over 50 supernovae, both teams discovered the intensity was weaker than expected. And when they determined the reason, their results shocked the scientific community.
For all their hard work, these three won the Physics Nobel Prize in 2011 and have also now won the 2015 Breakthrough Prize for fundamental physics. They are splitting the winnings 50-50 between the two teams.Stellar Recognition
Schmidt told The Australian that he was thrilled that his him and his colleagues' work was being recognized.
Ronald J. Daniels, president of Johns Hopkins University, attended the ceremony and told Johns Hopkins News, that "[this] work, which helped to change our very understanding of the universe, has inspired a spectrum of scientists, from colleagues working with the Hubble Space Telescope to young astronomers stargazing in their backyards."
This trio of astrophysicists is certainly venturing into new worlds with their work today. Perlmutter still heads the Supernova Cosmology Project, which continues to publish their work. One of the latest results was measuring the most distant Type Ia supernova using the Hubble Space Telescope.
Brian P. Schmidt's latest project is heading a project that will construct a new telescope to map the southern sky.
Adam Riess is involved with a few research projects, one being the Panoramic Survey Telescope & Rapid Response System which will study objects like asteroids and comets approaching Earth to assess whether they pose and danger to our planet.
While these researchers are basically superstars in their fields, they got to hobnob with celebrities at the event, and who helped present the awards: Kate Beckinsale, Benedict Cumberbatch, Cameron Diaz, Jon Hamm, and Eddie Redmayne. On November 15, the Discovery Channel and the Science Channel will televise the ceremony 6 pm EST (3 pm PST). And BBC World News will televise it on Nov. 22.
"I think breakthroughs are the things that mark achievements out as being truly unique in a scientist's life," Cumberbatch said during a red carpet interview at the ceremony. "But there's also alot of incredible work that goes on in the back room that's a slow burn that doesn't result in eureka moments or breakthrough moments which also needs acknowledgments. So it's about endurance as well as those far out moments."
The awards were founded in 2013 by science and technology gurus including Mark Zuckerberg, Anne Wojcicki (co-founder and CEO of personal genomics company 23andMe), and Jack Ma, founder of the Alibaba Group.
"The remarkable scientists we honor refuse to accept conventional wisdom as we know it," said Ma in a statement. "They question everything. They venture into new worlds."
See Also:Humans Are About To Land A Probe On A Comet For The First Time — Here's How To Watch LiveAstronomers Caught This Amazing Stellar Pulse With The Hubble TelescopeThese Stunning Hubble Images Show Us The Secrets Of The Universe
SEE ALSO: 12 People Just Won $3 Million Each For Breakthroughs In Science And Math
READ MORE: There's An Excellent Reason Why A Blue Lightbulb Just Won The Nobel Prize | 0.895807 | 3.749885 |
Astrophysicists predict Earth-like planet in star system only 16 light years away
The team investigated the star system Gliese 832 for additional exoplanets residing between the two currently known alien worlds in this system. Their computations revealed that an additional Earth-like planet with a dynamically stable configuration may be residing at a distance ranging from 0.25 to 2.0 astronomical unit (AU) from the star.
"According to our calculations, this hypothetical alien world would probably have a mass between 1 to 15 Earth's masses," said the lead author Suman Satyal, UTA physics researcher, lecturer and laboratory supervisor. The paper is co-authored by John Griffith, UTA undergraduate student and long-time UTA physics professor Zdzislaw Musielak.
The astrophysicists published their findings this week as "Dynamics of a probable Earth-Like Planet in the GJ 832 System" in The Astrophysical Journal.
UTA Physics Chair Alexander Weiss congratulated the researchers on their work, which underscores the University's commitment to data-driven discovery within its Strategic Plan 2020: Bold Solutions | Global Impact.
"This is an important breakthrough demonstrating the possible existence of a potential new planet orbiting a star close to our own," Weiss said. "The fact that Dr. Satyal was able to demonstrate that the planet could maintain a stable orbit in the habitable zone of a red dwarf for more than 1 billion years is extremely impressive and demonstrates the world class capabilities of our department's astrophysics group."
Gliese 832 is a red dwarf and has just under half the mass and radius of our sun. The star is orbited by a giant Jupiter-like exoplanet designated Gliese 832b and by a super-Earth planet Gliese 832c. The gas giant with 0.64 Jupiter masses is orbiting the star at a distance of 3.53 AU, while the other planet is potentially a rocky world, around five times more massive than the Earth, residing very close its host star—about 0.16 AU.
For this research, the team analyzed the simulated data with an injected Earth-mass planet on this nearby planetary system hoping to find a stable orbital configuration for the planet that may be located in a vast space between the two known planets.
Gliese 832b and Gliese 832c were discovered by the radial velocity technique, which detects variations in the velocity of the central star, due to the changing direction of the gravitational pull from an unseen exoplanet as it orbits the star. By regularly looking at the spectrum of a star - and so, measuring its velocity - one can see if it moves periodically due to the influence of a companion.
"We also used the integrated data from the time evolution of orbital parameters to generate the synthetic radial velocity curves of the known and the Earth-like planets in the system," said Satyal, who earned his Ph.D. in Astrophysics from UTA in 2014. "We obtained several radial velocity curves for varying masses and distances indicating a possible new middle planet," the astrophysicist noted.
For instance, if the new planet is located around 1 AU from the star, it has an upper mass limit of 10 Earth masses and a generated radial velocity signal of 1.4 meters per second. A planet with about the mass of the Earth at the same location would have radial velocity signal of only 0.14 m/s, thus much smaller and hard to detect with the current technology.
"The existence of this possible planet is supported by long-term orbital stability of the system, orbital dynamics and the synthetic radial velocity signal analysis", Satyal said. "At the same time, a significantly large number of radial velocity observations, transit method studies, as well as direct imaging are still needed to confirm the presence of possible new planets in the Gliese 832 system."
In 2014, Noyola, Satyal and Musielak published findings related to radio emissions indicating that an exomoon could be orbiting an exoplanet in The Astrophysical Journal, where they suggested that interactions between Jupiter's magnetic field and its moon Io may be used to detect exomoons at distant exoplanetary systems. | 0.862979 | 3.623759 |
While many other space missions are interested in Mars, The Japanese Aerospace Exploration Agency (JAXA) is planning to investigate Phobos and Deimos.
In the coming decades, the world’s largest space agencies hope to mount some exciting missions to the Moon and to Mars. Between NASA, Roscosmos, the European Space Agency (ESA), the Chinese National Space Agency (CNSA) and the Indian Space Research Organization (ISRO), there is simply no shortage of proposals for Lunar bases, crewed missions to Mars, and robotic explorers to both.
However, the Japanese Aerospace Exploration Agency (JAXA) has a different mission in mind when it comes to the coming decades. Instead of exploring the Moon or Mars, they propose exploring the moons of Mars! Known as the Martian Moons Exploration (MMX) mission, the plan is to have a robotic spacecraft fly to Phobos and Deimos to explore their surfaces and return samples to Earth for analysis.
The spacecraft would be deployed sometime in the 2020s, and would be tasked with two main objectives. The first would be to help scientists determine the origins of Phobos and Deimos, which has been a subject of debate for some time. Whereas some believe that these moons are capture asteroids, others have argued that they were created when fragments ejected from Mars (due to giant impacts on the surface) came together.
As Dr. Masaki Fujimoto, a Professor at JAXA’s Institute of Space and Astronautical Science (ISAS) and the Team Manager of the MMX mission, told Universe Today via email:
“MMX will land on Phobos and acquire samples of at least 10 grams from more than 2cm below the surface. Analysis of samples returned to Earth will clarify the nature of the asteroid that led to the formation of the moon. Deimos observations will be limited to flyby imaging, but combined with ground data to be obtained for Phobos, we should be able to constrain its origin in a substantial manner.”
The second objective focuses on the characterization of conditions both on and around the moons of Mars. This includes surface processes on Phobos and Deimos, the nature of the environment in which they orbit, and the global and temporal dynamics of Mars atmosphere – i.e. dust, clouds and water vapor.
“Airless bodies such as asteroids are exposed to space weathering processes,” said Dr. Fujimoto. “In the case of Phobos, an impact event on the surface releases many dust particles. Unlike an asteroid in the interplanetary space, dust particles will not be simply lost but will orbit around Mars and return and hit the Phobos surface. This is regarded as the reason that Phobos has a very thick regolith layer. Knowing this process is to know the attributes of returned samples better.”
Another major objective of this mission is to learn more about small bodies coming from the outer Solar System. As the outermost rocky planet, Mars’ orbit marks the boundary between the terrestrial planets – which have solid surfaces and variable atmospheres (ranging from super-thing to dense) – and the gas and ice giants of the outer Solar System that have highly dense atmospheres.
Because of this, studying Mars’ moons, determining their origin, and learning more about the Martian orbital environment could teach us a lot about the evolution of the Solar System. Not only does such a mission present opportunities to study how planets like Mars formed, but also the process of by which primordial materials were transported between the inner and outer Solar Systems during its early history. As Dr. Fujimoto explained:
“These small bodies were the delivery capsules for water from outside the Frost Line to the Habitable Zone of the solar system, where our planet is situated. Earth was born dry and needed delivery of water for its habitability to be switched on at all. It is likely that one of the (failed) deliveries led to the formation of Phobos, and, sample analysis will tell us about the failed capsule.
“This is obviously the case when the capture idea turns out to be correct. Even for the case of giant impact, the scale of the impact is considered to be not too gigantic to alter fully the materials, implying that sample analysis would tell us something about the impactor asteroid.”
As it stands, the probe is scheduled to launch in September 2024, taking advantage of the fact that Earth and Mars will be at the nearest point to each other in their orbits at this time. It will arrive around Mars by 2025, conduct its studies for a three-year period, and then return to Earth by July of 2029. Once there, it will rely on a suite of scientific instruments to conduct surveys and obtain samples.
These instruments include a Neutron and Gamma-ray Spectrometer (NGRS), a Near-Infrared Spectrometer (NIRS), a Wide Angle Multiband Camera (WAM), a Telescopic Camera (TL), a Circum-Martian Dust Monitor (CMDM), a Mass Spectrum Analyzer (MSA), and a Light Detection and Ranging (LIDAR) instrument.
Details on the mission profile and the instruments were included in a presentation made by Dr. Fujimoto and the MMX Science Board members at the recent 48th Lunar and Planetary Science Conference. The mission profile and information on the objectives were also made available in an abstract that was issued in advance of the upcoming European Planetary Science Congress 2017.
The mission will also leverage some key partnerships that JAXA is currently engaged in. These include an agreement reached with NASA back in late March to include the Neutron and Gamma-ray Spectrometer (NGRS) in the MMX’s instrument suite. And in April, JAXA and the National Center for Space Studies (CNES) signed an Implementation Agreement (IA) that would allow the French national space agency to participate in the mission as well.
If all goes as planned, JAXA will be spending the next decade gathering information that could bridge findings made by Lunar and Martian missions. Whereas lunar research will reveal things about the history of the Moon, and Martian missions will offer new insights into Mars’ geology and evolution (and perhaps if life still exists there!), the MMX mission will reveal things about the history of Mars’ moons and the early Solar System as a whole.
Other proposals that JAXA is currently working on include the Jupiter Icy Moons Explorer (JUICE) and SPICA, two missions that will explore Jupiter’s Galilean Moons and conduct infrared astronomy (respectively) in the coming decade.
Source: Universe Today | 0.900286 | 3.468508 |
Thousands of tiny eyes just blinked open and will soon scan 35 million galaxies for evidence of dark energy.
These 5,000 mini-telescopes make up the Dark Energy Spectroscopic Instrument (DESI), which was installed on the Mayall Telescope at the Kitt Peak National Observatory in Arizona. Astronomers recently completed the first test run of the nearly-complete DESI, which, from its high mountain perch, will soon scan the cosmos for dark energy, beginning early next year.
"With DESI, we are combining a modern instrument with a venerable old telescope to make a state-of-the-art survey machine," Lori Allen, director of Kitt Peak National Observatory at the National Science Foundation's National Optical-Infrared Astronomy Research Laboratory, said in a statement.
Dark energy is an invisible force that's thought to be accelerating the expansion of the universe and is thought to make up 68% of it, according to the statement.
DESI is designed to provide precise measurements of the rate of expansion of the universe. To figure out how much of the universe expanded as light from different galaxies traveled to Earth, the instrument will detect light from a particular set of galaxies, split that light into narrow bands of color and use each of those bands to measure the galaxies' distances from our planet.
The instrument is equipped with spectrographs, which split the light and also measure redshift, or the shift in the color to the longer, redder wavelengths of light from objects moving away from us. In five years, the statement said, DESI will have scanned 35 million galaxies and 2.4 million quasars, the brightest objects in the universe.
In the best conditions, DESI can analyze 5,000 galaxies every 20 minutes, according to the statement. These telescopes can also shift their gaze quickly. It takes about 10 seconds for these eyes, which each have a single fiber-optic cable the width of a human hair, to refocus from one set of galaxies to another, according to the statement.
What's more, DESI will be able to peer into the distant, early universe, going back in time to about 11 billion years ago. At that time, gravity is thought to have slowed the universe's expansion, whereas now, dark energy is thought to be speeding the expansion up.
"By looking at objects very far away from us, we can actually map the history of the universe and see what the universe is composed of by looking at very different objects from different eras," Nathalie Palanque-Delabrouille, a DESI spokesperson and an astrophysics researcher at France’s Atomic Energy Commission (CEA), said in the statement.
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Originally published on Live Science. | 0.800775 | 3.842157 |
CAPE CANAVERAL, Fla. (AP) — In a tantalizing first, scientists have discovered water at a planet outside our solar system that has temperatures suitable for life.
Two research groups announced this week that they’ve found water vapor in the atmosphere of a planet 110 light-years away in the constellation Leo. This so-called Super Earth is just the right distance from its star to conceivably harbor life.
It’s the only exoplanet known so far to have both water and temperatures needed for life, the University College London team reported in the journal Nature Astronomy on Wednesday. But lead author Angelos Tsiaras stressed, “This is definitely not a second Earth.”
Its star and atmosphere are so different than ours, “Earth-like conditions are not possible,” Tsiaras told reporters. “The only question that we’re trying to ask here, and we’re pushing forward, is the question of habitability.”
A Canadian-led team announced similar findings Tuesday. In a paper just submitted to the Astronomical Journal for publication, these scientists suggest it might even be raining there.
“This represents the biggest step yet taken toward our ultimate goal of finding life on other planets, of proving that we are not alone,” the study’s lead astronomer, Bjorn Benneke of the University of Montreal, said in a statement.
Discovered in 2015, the planet known as K2-18b is twice the size of Earth with eight times the mass. While it’s thought to be rocky, no one knows if water’s flowing on the surface. Its star, a red dwarf, is considerably smaller and cooler than our sun, a yellow dwarf, and its atmosphere is also different than ours.
Nonetheless, Tsiaras said K2-18b could help determine, “Is the Earth unique?”
The results are doubly exciting, Tsiaras noted, given this is not only the first Super Earth with water detected in its atmosphere but the planet also resides within the habitable zone of its star.
The research teams used archived data from the Hubble Space Telescope and other spacecraft to analyze the planet’s atmosphere. Further observations are needed to determine whether the planet is indeed a true water world, using next-generation observatories like NASA’s James Webb Space Telescope and the European Space Agency’s Ariel, both due to launch in the 2020s.
Future telescopes on Earth and in space should help uncover more Super Earths orbiting red dwarf stars — believed to be the most common planets and stars in our Milky Way galaxy. Super Earths are defined as having a mass greater than Earth but less than gas giants like Uranus and Neptune; more than 1,260 have been confirmed to date.
While water already has been identified in the atmospheres of hot gas giants circling other stars, the latest findings represent the first detection of water vapor in the atmosphere of another type of exoplanet, Tsiaras said.
A NASA tally currently lists more than 4,000 confirmed exoplanets and another 4,000 potential candidates. Most have been detected using the transit method, where telescopes watch for a slight, fleeting dimming of a star’s light as a planet passes in the field of view.
For now, scientists know K2-18b takes 33 days to orbit its star, so one year there is one month here. At this distance, temperatures range from minus-100 degrees to 116 degrees Fahrenheit (minus 73 degrees to 47 degrees Celsius.)
The star, glowing red in the day sky, is believed to bombard the planet with radiation harsh enough to quickly inflict any human visitors with cancer, although “life there may have evolved differently” in order to survive, noted the London team’s Ingo Waldmann. A sister planet, meanwhile, orbits closer to the star and is likely too hot to be in the habitable zone.
The cloud cover isn’t too thick on K2-18b, otherwise it would have obscured the water vapor in the atmosphere, according to the scientists.
The surface, meanwhile, could be wet or dry. The London data suggest water vapor makes up anywhere between 0.01% and 50% of the atmosphere — “quite a big range,” Waldmann acknowledged. Either way, given the planet’s mass, it would be difficult to walk on the surface.
“Maybe not quite your vacation destination just yet,” Waldmann joked.
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content. | 0.925128 | 3.503185 |
Ancient Comet Sightings Inspired, Frightened, Dazzled, and Baffled Past Astronomers and Star Gazers
Since the earliest days of humankind, our ancestors looked into the night sky and watched bright celestial spectacles we know today as comets. While modern astronomers have a rich understanding of the phenomenon, ancient comet sightings were thought of as heavenly messages and were often feared as omens of ill fortune.
Chaldean Astronomers Sight Comets
The European Space Agency website informs that the first systematic observations of the sky can be credited to the Chaldeans, who lived in the region of ancient Babylon, or modern day Iraq, around the third millennium BC. Clay tablets with explicit references to comets date from the last few centuries BC, but indirect sources, for example, the Roman philosopher Seneca, report that Chaldean astronomers had a keen interest in comets for a very long time.
Observation of Haley's Comet, recorded in Cuneiform on a clay tablet between 22-28 September 164 BC, Babylon, Iraq. British Museum, London. ( Public Domain )
Comets in Ancient China and Egypt
In ancient China, where events in the sky were believed to reflect events on earth , a comet suddenly appearing in the sky was thought to herald something of importance that was about to happen on earth, perhaps a major battle or the death of a noble. Chinese records of comets exist at least as far back as 613 BC, and historians believe records had been kept for many centuries before then. Ancient Chinese astronomical data accuracy is unsurpassed and was not overtaken by Western accuracy until the 15th century. This is demonstrated, for example, with Halley’s comet, which appears in the sky every 70 to 75 years and was painted by Chinese astronomers from about 3000 years ago.
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Detail of astrology manuscript, ink on silk, 2nd century BC, Han dynasty, unearthed from Mawangdui tomb. The page gives descriptions and illustrations of seven comets, from a total of 29 found in the document. (Public Domain )
In ancient Egypt, Pharaonic astronomical texts dating back to the ninth Egyptian dynasty (c. 2150 BC) name 36 stars which rise within 10 days of each other at the same time as the sun. Astronomers under Thutmosis III (1504-1450 BC) also recorded the apparition of what was later named Halley's comet.
Comets in the Middle Ages
By the Middle Ages, fear of comets had reached astronomical proportions and they were believed to portend natural disasters like floods and earthquakes. These so-called “tailed stars” appeared in famous works of art, such as the fresco Adoration of the Magi , by Renaissance painter Giotto di Bondone in the Cappella degli Scrovegni in Padua around 1304 AD. This image gave rise to the widespread belief that the Biblical Star of Bethlehem was actually a comet.
Original Title: Adorazione dei Magi, c.1304 - c.1306, Fresco. Series: Scenes from the Life of Christ. Scrovegni (Arena) Chapel, Padua, Italy. ( Public Domain )
A 15th century poem provides historians with an impressive insight into the Medieval beliefs in the supernatural nature of comets: “They bring fever, illness, pestilence and death, difficult times, shortages and times of great famine.”
In 1540 AD, Peter Bienewitz (1495-1552) was the first astronomer of modern times to make the observation that comets’ tails always pointed away from the sun. He wrote about this in his book Astronomicum Caesareum. Three decades later, the famous Danish astronomer Tycho Brahe (1546-1601) measured the parallax of a comet which appeared in 1577 AD to be around 230 Earth radii, corresponding to 1.5 million kilometers. This measurement refuted the teachings of Aristotle, who believed comets to be phenomena generated “within” the terrestrial atmosphere, and Brahe proved that comets were independent celestial bodies.
About a terrible and marvelous comet as appeared the Tuesday after St. Martin's Day (1577-11-12) on heaven. (Written by Peter Codicillus of Tulechova) A depiction of the Great Comet of 1577 over Prague. In addition to the comet, five zodiac symbols appear in the sky: (L-R) Aries, Pisces, Aquarius, Capricorn, and Sagittarius. Below the comet's tail are the crescent moon and Saturn, depicted as a star with the astronomical symbol ♄. At the bottom center, a man draws the comet by the light of a lantern. ( Public Domain )
A dispute emerged regarding the trajectory of comets and the cause of their trails, which was presented on the title page of Hevelius’ Cometographia, published in 1665 AD. On one hand, Tycho Brahe predicted that comets would return periodically, however, Johannes Kepler (1571-1630) believed they projected in straight lines. This argument was later settled by Danzig alderman and astronomer, Johannes Hevelius (1611-1687), who proposed that comets traveled in elongated parabolas and hyperbolas, as we now know they do.
Illustration of comet tail shapes featured in Johannes Hevelius’, ‘ Tavola N dell'opera Cometographia di Johannes Hevelius.’ ( Public Domain )
Halley’s Comet and Hale-Bopp
When we were in junior school, there was only ever one comet talked about, famously named after the 24-year-old Edmond Halley (1656-1742) who in 1680 explained to his friend Isaac Newton that the comet probably had a “sharply curved” trajectory. In scholar Peter Lancaster Brown’s 1985 book Halley & His Comet we learn that with this primary observation, Halley entered a world of celestial dynamics and spherical geometry, and he calculated that the comets’ elongated ellipse should cause it to return in 1758. On the evening of December 25, 1758 the amateur astronomer Johann Georg Palitzsch (1723-1788) reported a weak spot of light in the Pisces constellation… The Halley’s comet returned just as predicted.
Hale-Bopp was the last bright comet seen from Earth. It appeared in the terrestrial sky in the spring of 1997. Since then, comet technology has advanced at such a rate that a mission to comet Wild 2 showed crater-covered “space potatoes” ejecting frozen material into space, which has remained almost unchanged since it originated 4.5 billion years ago.
C/2014 Q2 (Lovejoy) is a long-period comet discovered on 17 August 2014 by Terry Lovejoy. This photograph was taken from Tucson, Arizona, using a Sky-Watcher 100mm APO telescope and SBIG STL-11000M camera. (John Vermette/ CC BY SA 4.0 )
Modern Technology and the Study of Comets
Journeying towards the sun, comet gases vaporize and form a thin extended atmosphere known as the coma. Flows of electrically charged particles called solar winds are generated by the sun and travel through space at a speed of 400 kilometers per second, which forms the comet’s tail - the archetypal aesthetic feature of a comet which can measure 100s of millions of kilometers.
Today, astronomers are performing acts of mechanical and engineering genius which were beyond the wildest dreams of even the brightest minds in ancient history. Comet ‘Tempel 1’ was photographed 67 seconds after it collided with Deep Impact by a high-resolution camera mounted on a spacecraft flying by the event. The following image reveals the comets ridges, scalloped edges and impact craters.
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Comet ‘ Tempel 1’ passed close to the Sun and warmed up, releasing gases in a process known to astronomers as outgassing, which produces a visible coma and sometimes a tail. ( Public Domain )
Space rubble around comets consists of very fine particles and larger rocks which solar winds blow off the surface a comet. When Earth passes through a field of this material, the particles penetrate the atmosphere and appear to race across the sky in a phenomena we call shooting stars. The largest pieces of space rubble that penetrate the terrestrial atmosphere fall to Earth as meteorites.
The Hoba West meteorite impact is thought to have occurred more recently than 80,000 years ago and this space rock is still located on a farm near Grootfontein, in the Otjozondjupa Region of Namibia. Its extreme mass means it has never been moved from the spot it collided with the surface of Earth. Estimated at more than 60 tons, it’s the largest known meteorite (as a single piece) known to scientists. The name "Hoba" comes from a Khoekhoegowab word meaning “gift”, and in an attempt to control vandalism the government of South West Africa (now Namibia) on March 15, 1955, declared the Hoba meteorite to be a national monument.
The Hoba meteorite near Grootfontein, Namibia. (Sergio Conti/ CC BY SA 2.0 )
Top Image: A foreboding comet crossing the sky. Ancient comet sightings were often linked to important, and sometimes frightening, events in the minds of those who witnessed them. Source: CC0
By Ashley Cowie
European Space Agency. (2014) ‘A History of Comets - Part 1: From harbingers of doom to celestial wanderers.’ European Space Agency. Available at:
Lancaster-Brown, P. (1985), Halley & His Comet . Blandford Press. p. 76.
Richard, S. & K. Yau. (1984) ‘Oriental tales of Halley's Comet,’ New Scientist, vol. 103, no. 1423, pp. 30–32, 27
Theophile, O. (1903) Ancient Egypt & Black Africa : Karnak House, London, Bibliotheque Egyptologique, Vol.X1.Paris.
The Met. (n.d.) ‘Astronomicum Caesareum.’ Heilbrunn Timeline of Art History. Available at:
The Meteorology Society. (1920) Namibia. Available at: | 0.804002 | 3.347712 |
Light absorption enhancement with bio-inspired nanostructures
Sunlight is the primary energy source for life on earth. In some habitats like the ocean the solar irradiance is reduced. Species living in such an environment have developed strategies to harvest the scarce sunlight in an effective way: Diatoms, a unicellular microalga, have a silica microshell with intriguing optical properties . The planktonic living algae utilize this feature to collect the sparse sunlight and maximize their rate of photosynthesis . A similar problem needs to be overcome by the solar panels that power spacecraft. The size of the solar arrays is proportional to the power demand of the spacecraft. Making the absorption of sunlight in the solar arrays more effective provide more power to the spacecraft and alleviate mission analysis constraints.
The silica microshell of diatoms is species-specific and can have various shapes. All diatoms have a silica shell that contains pores that can have either a circular, elongated or polygonal . For example the shell of the diatom Coscinodiscus sp. is built up by several porous layers with different pore sizes and lattice constants in a hexagonal array [1,4]. The pore size increases from ca. 50 nm in the outermost layer to 1300 nm in the innermost layer with lattice constants from 200 nm to 2000 nm . This structure is a natural three-dimensional photonic crystal. The optical properties of the silica shell have been described to be capable of “light-trapping” , “lensless light focusing” or “light-confining” . The physical manipulation of the light is based on the superposition of scattered light. Consequently the photonic crystal layers act differently on varying wavelengths and polarizations . In previous research, two-dimensional photonic crystals with patterns comparable to the diatom shell have been successfully applied to single junction solar cells and thin-film solar cells .
Another natural structure with potential to enhance solar cells in space are bio-inspired anti-reflective coatings. The model for these structures can be found on the surface of the eyes of several insects, for example moths .
This ACT project aims to investigate the potential of enhancing the external quantum efficiency of solar panels used on space craft with bio-inspired nanostructures.
- Chen, X., Wang, C., Baker, E., Sun, C. (2017) Numerical and experimental investigation of light trapping effect of nanostructured diatom frustules. Scientific Reports, 5:11977
- De Tommasi, E. (2016): Light Manipulation by single cells: The case of diatoms. Journal of Spectroscopy, 2490128
- Round, F. E., Crawford, R. M., Mann, D. G. (1990) The diatoms. Biology & morphology of the genera. Cambridge University Press, Cambridge, 5
- Fuhrmann, T., Landwehr, S., El Rharbi-Kucki, M., Sumper (2004) Diatoms living as photonic crystals. Applied Physics B 78, 257-260
- De Stefano, L., Rea, I., Rendina, I., De Stefano, M., Moretti, L. (2007) Lensless Light focusing with the centric marine diatom Coscinodiscus walesii. Optics Express 18082, Vol. 15, No. 26
- Joannopoulos J. D., Johnson, S. G., Winn, J. N., Meade, R., D. (2008) Photonic Crystals – Molding the flow of Light. Second Edition, Princeton University Press, 2
- for space applications using two-dimensional photonic crystals. E3S Web of Conferences 16, 16007
- Zhou, H., Xu, J., Liu, X., Zhang, H., Wang, D., Chen, Z., Zhang, D., Fan, T. (2017) Bio-inspired Photonic Materials: Prototypes and Structural Effect Designs for Applications in Solar Energy Manipulation. Advanced Functional Material, 1705309 | 0.800368 | 3.15159 |
I don’t know about you, but these past few weeks have felt like we live on a cloud-covered planet … clouds, clouds and more clouds. If, and when, the clouds break, there is a bright “star” that will catch your attention in the southeast sky right after dark.
The brightest stellar-like object in the night sky is not a star but mighty Jupiter, the “king of the planets.” You can’t miss Jupiter, even in downtown D.C. — it is that bright. Only the moon is brighter in the night sky.
On 11 p.m. EDT Tuesday, Jupiter will be at its closest to our planet for all of 2019; it will be 398 million miles away. When you look at Jupiter, take a peek to see what time it is, then subtract 36 minutes. This is the time that the light from the sun that was reflected off Jupiter’s cloud tops left the planet traveling at 186,000 miles per second — the speed of light.
With good binoculars, you can see the four main moons of Jupiter, discovered by Galileo. Galileo first observed these moons on Jan. 7, 1610, and he noticed that they moved over a period of time.
Here is a nifty calculator that shows you which moon is which for any given time and date. Use the “Direct View” if looking through binoculars. The number of moons present is always changing due to their orbiting Jupiter.
Jupiter has made news in the astronomical community lately because the “bigger than Earth” storm known as the “Great Red Spot,” visible in even small telescopes for hundreds of years, may be “evaporating.”
By contrast, the bright reddish-orange star to the right of Jupiter, Antares, is 550 light-years away! The light you see when you look at Antares left in 1469. And, if you’re into big numbers, Antares is 3.3 quadrillion (3,300,000,000,000,000) miles from Earth. Antares is known as the “Heart of the Scorpion.” It’s the brightest star in Scorpius, a constellation that really looks like its namesake.
Jupiter and Scorpius are just to the right of the bright band of the Milky Way, our home galaxy. If you’re lucky enough to view this nighttime scene from a dark sky with no moon present, it will be quite spectacular.
We’re entering into Milky Way season, when the bright band of our galaxy rises above the eastern and southern horizons to pass high overhead in the summer months, especially August.
If you look further to the left of Jupiter, you’ll notice a bright yellowish-white “star.” That’s Saturn, which is twice as far away as Jupiter at 76 light-minutes and almost 900 million miles distant.
If you have a telescope, Jupiter, and all of the sky sights discussed are really worth a look — especially the rings of Saturn.
Enjoy these sky sights of summer and mark your calendar: The 4th annual “Night Sky Festival at Shenandoah National Park” will be Aug. 9-11. See you there! | 0.818221 | 3.404894 |
by D.W. Euring, May 20, 2020 in PrincipiaScientificInternational
It became apparent from investigation of the Variability of the Gravitational Constant that Jupiter’s orbit is affecting the Sun’s surface temperature and driving the Sunspot Cycle which appear to be triggered at its Aphelion and suppressed at Perihelion.
Saturn has even greater eccentricity than Jupiter and it is noted that it was at Perihelion at the end of 1972 which seems to account for the Low Solar Maximum at that time and a particular dip after the main peak. So, whilst cycle periods are not influenced by Saturn, it does impact on their magnitude, and it seems likely that it will have augmented in 1957-58 as well as 1990.
by K. Richard, December 24, 2018 in NoTricksZone
Between 60 and 40 thousand years ago, during the middle of the last glacial, atmospheric CO2 levels hovered around 200 ppm – half of today’s concentration.
Tree remains dated to this period have been discovered 600-700 meters atop the modern treeline in the Russian Altai mountains. This suggests surface air temperatures were between 2°C and 3°C warmer than today during this glacial period.
Tree trunks dating to the Early Holocene (between 10.6 and 6.2 thousand years ago) have been found about 350 meters higher than the modern treeline edge. This suggests summer temperatures were between 2°C and 2.5°C warmer than today during the Early Holocene, when CO2 concentrations ranged between about 250 and 270 ppm.
None of this paleoclimate treeline or temperature evidence correlates with a CO2-driven climate.
by Rice University, November 19, 2018 in ScienceDaily
Their study in the journal Geophysical Research Letters is based on an analysis of fossil signatures from deep ocean sediments, the magnetic signature of oceanic crust and the position of the mantle “hot spot” that created the Hawaiian Islands. Co-authors Richard Gordon and Daniel Woodworth said the evidence suggests Earth spun steadily for millions of years before shifting relative to its spin axis, an effect geophysicists refer to as “true polar wander.”
“The Hawaiian hot spot was fixed, relative to the spin axis, from about 48 million years ago to about 12 million years ago, but it was fixed at a latitude farther north than we find it today,” said Woodworth, a graduate student in Rice’s Department of Earth, Environmental and Planetary Sciences. “By comparing the Hawaiian hot spot to the rest of the Earth, we can see that that shift in location was reflected in the rest of the Earth and is superimposed on the motion of tectonic plates. That tells us that the entire Earth moved, relative to the spin axis, which we interpret to be true polar wander.”
La géologie, une science plus que passionnante … et diverse | 0.895635 | 3.519655 |
Welcome to my monthly roundup of the activities of our intrepid robotic emissaries across the solar system! I count 16 spacecraft that are actively performing 13 scientific missions at Mercury, Venus, the Moon, Mars, Vesta, Saturn, and at the edge of the heliosphere, while another 9 are cruising to future destinations. And my count doesn't include all the spacecraft observing Earth, Sun, and points beyond our Sun's reach.
So, what highlights do we have to look forward to in April 2012? The Cassini Saturn orbiter is in the middle of a busy stretch of several orbits that take it close by Saturn's icy moons, offering lots of opportunities for great images, which get posted (as always) to JPL's Cassini Raw Images website almost as soon as they arrive on Earth. It's Mars' southern winter solstice today, so Opportunity's power levels are beginning to pick up again. Ebb and Flow are in the full swing of science operations at the Moon, and will be streaming thousands of MoonKAM photos to Earth over the coming months. And MESSENGER will shortly start lowering its orbit at Mercury.
Below I'll get to much more detailed summaries of each mission's activities, but first, here's Olaf Frohn's diagram of where all our wandering spacecraft are as of April 1. Compare it to last month's to see how things have moved.
Solar system exploration missions in April 2011
Exploring the inner solar system:
NASA's MESSENGER Mercury orbiter announced a few weeks ago that they've been granted a one-year mission extension, doubling their operational time at Mercury. They'll be adjusting their elliptical orbit from its current 12-hour period to a faster, lower 8-hour one, giving them much more time close to the planet for their fields and particles instruments to gather data on the composition of the planet and its atmosphere, the structure of the magnetic and gravity fields, and the shape of its interior. The lower orbit will also allow an incremental improvement to their topographic maps, allowing them to be extended a little farther south. But the most important reason to extend the mission is that the Sun is moving to a much more active phase of its 11-year cycle, and MESSENGER will get to watch how the Sun's changing activity changes the environment around Mercury. Last month the team released a huge amount of data to the Planetary Data System, as well as an iOS app that makes it easy to find the latest photos and to find out where MESSENGER is. I have tried out the app and actually find it to be an easier way of browsing their image releases than their web gallery is. This possibly volcanic collapse pit in Tolstoj is pretty cool.
ESA's Venus Express Venus orbiter remains in orbit on a mission that has been extended through 2014. After a long hiatus, ESA has resumed posting mission updates to the Venus Express Science & Technology site. These updates are extremely detailed and worth reading for the insight they provide into routine operations on an orbiting mission. The latest update describes the preparations Venus Express had to perform to be ready for its 20th "eclipse season," when its orbit around Venus takes it into Venus' shadow. Eclipses are challenging for spacecraft both because conditions suddenly get very chilly and because most spacecraft are solar-powered; they must rely on batteries to survive through each eclipse.
Ebb and Flow, the twin spacecraft of NASA's GRAIL mission, are now mapping the Moon's gravity. Last month the MoonKAM project also got underway; check the MoonKAM website for the latest student-requested images from the tiny cameras on the two spacecraft. I like shots across the lunar limb. I've inquired with the MoonKAM team about whether they plan to provide a facility to batch download their images, and they do not; their site also blocks wget. So it's hard to grab a lot of images to make animations or mosaics, unfortunately. There are other tools out there that can download all the images from the site, and I have found one, but I don't want to mention it here for fear they'll block that one too!
NASA's ARTEMIS spacecraft are presumably still orbiting the Moon, but there's no recent mission status information available. They were sent into lunar orbit in 2011 to study the Moon's magnetic field, and should last for at least seven years.
China's Chang'E 2 lunar orbiter is now at L2, the Lagrange point on the far side of Earth from the Sun, having arrived there in August 2011. According to this Xinhua article, the plan is for it to stay there for a year. I'm eager to receive more information on the status of this mission!
Out at Mars, today is the southern winter solstice. (It's currently Ls 89.8 of Mars Year 31.) The Mars Exploration Rover Opportunity's sol 2908 is drawing to a close. We're now past the winter solstice, so Opportunity's power levels are picking up (her panels are producing 306 watt-hours, 30 more than last month). They're still parked at the north edge of Cape York on the rim of Endeavour crater, keeping still in order to perform careful radio tracking of the rover's position, an operation that should allow them to determine whether Mars has a liquid outer core like Earth's. They're also occupied with trying to figure out why the left-front wheel suddenly shifted position and the robotic arm stalled on sol 2899. According to the last report, everything is fine with the arm. Here is Eduardo Tesheiner's latest route map and Google Earth kml file for Opportunity (three months old now).
NASA's Mars Reconnaissance Orbiter is keeping an eye on Mars' weather with MARCI. As is usual for this time of Mars' year, near northern summer solstice, which coincides with aphelion, the atmosphere is stuffed with water from the endlessly illuminated northern polar cap, so there are clouds everywhere. As always, check in on the latest captioned image releases from HiRISE for your dose of spectacular photos, and make sure you follow the links at least as far as the browse versions of the images, because the thumbnails that are automatically posted with their voluminous image releases routinely fail to convey the awesomeness hidden in each photo. Enlarge this one, showing "some of the best exposures of ancient bedrock on Mars," within a region called Nili Fossae.
NASA's Mars Odyssey is now the longest-lived spacecraft ever to operate at Mars. You can see the latest from its THEMIS instrument here. Here's a nify photo from the flank of a Martian volcano, Apollinaris Mons, where wind has eroded deeply into the (likely) ashy deposits around the mountain, except where impact craters splatted out ejecta that formed an armor atop the ash.
In the Asteroid Belt:
NASA's Dawn asteroid orbiting spacecraft is still in Low Altitude Mapping Orbit around Vesta, averaging 210 kilometers' elevation. As stated in Marc Rayman's latest Dawn Journal, the spacecraft will pass through solar conjunction this month, and reach its farthest separation ever from Earth, at 520 million kilometers. Keep watching their daily image releases; here's a cool photo of two typical Vestian craters, with a rim sharp on one side and hummocky on the other. Once the Low-Altitude Mapping Orbit phase is complete, Dawn will raise its orbit to a second High-Altitude Mapping Orbit phase. By summer, Dawn will be able to see the north polar areas of Vesta that were in winter darkness during the previous mapping cycle. And in July, Dawn will depart Vesta for Ceres, which it will reach in early 2015. Here's a timeline summarizing the Vesta phase of the Dawn mission.
The NASA-ESA-ASI Cassini Saturn orbiter is now wrapping up its Rev 163. It has just completed very close flyby of the geyser moon Enceladus, and performed some very cool imaging of moons Janus and Dione at nearly the same time. Cassini will perform two more close flybys of Enceladus on April 14 and May 2, also passing pretty close to Tethys on the first one. These will be Cassini's last targeted flybys of moons other than Titan until March 2013, as Cassini's orbit will be dropping away from the ring plane after the May 2 encounter. To see what Cassini's doing when, check out my long and detailed page on Cassini's tour of the Saturn system, and look to the Looking Ahead page for more detailed information.
Cruising from here to there:
NASA's New Horizons has 9.61 AU to go to reach Pluto. There are 1200 days left until Pluto closest approach. New Horizons is on course for a January to July 2015 encounter with the Pluto and Charon system. Cosmoquest has recently started a new citizen science project, the successor to IceHunters, called Ice Investigators. The goal is still to discover a good Kuiper belt target for the New Horizons mission.
NASA's Juno spacecraft is outbound from the Sun, heading way beyond Mars' orbit before heading sunward again. An Earth flyby in August 2013 will send it on to a July 2016 Jupiter arrival.
NASA's next great Mars rover, Curiosity, or Mars Science Laboratory, is now 53 million kilometers from Mars and closing. A recent status report says that their second trajectory correction maneuver was successful, and that nine of Curiosity's instruments have been powered on and checked out. All of the instruments have passed their checkouts. Curiosity will be landing in Gale crater, next to a mountain that's recently been (informally) named Mount Sharp, on August 6, 2012, just after 5:00 UTC (August 5, after 10:00 p.m. here in Los Angeles). On Mars, it will be in the midafternoon of a late winter day in the southern hemisphere at the landing site at 4.49°S, 137.42°E. Its nominal mission will last one year but it should go on much longer.
JAXA's Akatsuki is now in solar orbit, on its long cruise to a second encounter with Venus.
JAXA's IKAROS is now hibernating. It has nearly exhausted its maneuvering fuel, so can no longer maintain a minimum solar incidence angle on its solar cells, reducing available power. It was last heard from on December 24, 2011.
ESA's Rosetta is now on the final, long leg of its cruise to its target comet. It's been placed into hibernation and will not communicate with Earth again until January 2014. The next object it'll encounter will be its goal, comet 67/P Churyumov-Gerasimenko; rendezvous is set for May 2014.
The International Cometary Explorer remains on course for a return visit to Earth in 2014. When it does, ICE can be returned to a Sun-Earth L1 halo orbit, or can use multiple Earth swingbys to encounter Comet Wirtanen during its near-Earth apparition in December 2018. | 0.863421 | 3.309136 |
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