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BepiColumbo will speed pass Earth on Thursday on its way to Venus.
BepiColombo—a spacecraft launched in 2018—is coming home. Briefly.
On April 10, 2020, the European Space Agency’s BepiColombo—which is bound for Mercury—will conduct a flyby of Earth at a distance of 7,877 miles/12,677 kilometres. It might seem like an odd thing for a spacecraft that launched on October 20, 2018 to do, but it’s a crucial part of its seven-year journey from Earth to Mercury.
It’s what space engineers call a “gravity assist”—and this one comes with bonus science for astronomers interested in our Moon, which this week just happens to be in its full phase as a “Super Pink Moon.”
What is ‘gravity assist?’
Due to the enormous gravitational field of the Sun, planetary missions have to follow very complex trajectories. The “gravity assist” assist manoeuvre will slow down BepiColombo and slightly alter its trajectory, sending it off towards the orbit of Venus. BepiColombo will then conduct two Venus flybys—in October 2020 and August 2021—before finally arriving at Mercury in 2025.
Aside from achieving the mission’s objectives, BepiColombo’s brief Earth flyby will provide a unique opportunity for planetary researchers and engineers to conduct a unique experiment with the Moon.
How BepiColumbo will study the Moon
Onboard BepiColumbo is Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) instrument, which was developed and built at the German Aerospace Center and the Institute for Planetology at the Westphalian Wilhelms University of Münster. MERTIS has two uncooled radiation sensors and can take images in the thermal infrared. It will identify rock-forming minerals in the mid-infrared at a spatial resolution of 500 metres.
The Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) instrument.
DLR (CC-BY 3.0)
So on April 9, with its Earth-facing side illuminated by the Sun as a “Super Pink Moon,” our satellite will be observed for the first time in the thermal infrared and examined for its mineralogical composition—something it’s being sent to Mercury do.
This is not something that can be done from Earth; it’s only possible for BepiColumbo to do with the Moon because the light won’t be absorbed by Earth’s atmosphere.
MERTIS will observe the Moon from distances of between 460,000-422,000 miles/740,000-680,000 kilometres for four hours.
As a bonus, three small cameras on the exterior of the BepiColombo spacecraft will also snap photos of Earth during the approach.
‘One of a kind’ opportunity
“Observing the Moon with our MERTIS instrument on board BepiColombo is a one-of-a-kind opportunity,” said Joern Helbert from the DLR Institute of Planetary Research, who is a Co-Principal Investigator for MERTIS. “We will examine the Earth-facing side of the Moon spectroscopically in the thermal infrared for the first time.”
“We will obtain new information on rock-forming minerals and the temperatures on the lunar surface and will later be able to compare the results with those acquired at Mercury,” said Harald Hiesinger from the University of Münster, Principal Investigator for the MERTIS experiment.
It’s also a chance to test how well MERTIS works in advance of its arrival at Mercury.
These four images of the Moon were created using infrared image data acquired in December 1992 … [+]
How sharp will the infrared Moon photos be?
Although there won’t be any absorption by Earth’s atmosphere, and the view from space will provide a valuable new data set for lunar research, don’t expect pin-sharp pictures. “We will not be able to obtain such a detailed resolution when observing the Moon,” said Gisbert Peter, MERTIS Project Manager at the DLR Institute of Optical Sensor Systems. “Having the Moon in the spectrometer’s field of view before the flyby is partly an astronomical or geometric coincidence and, above all, due to good planning.”
Will BepiColumbo be visible on Earth?
Yes, but only to some. Those south of 30º North—over the Atlantic, in South America, Mexico and in Texas and California—may see it (here’s how to find it). The telescopes of the European Southern Observatory (ESO) in Chile ought to pick it up, too.
“The Moon and Mercury are two important bodies that are fundamental to enhancing our understanding of the solar system,” said Hiesinger about the two similarly-sized bodies. “After about 20 years of intensive preparations, the time will finally come on Thursday — our long wait will be over, and we will receive our first scientific data from space.”
Wishing you clear skies and wide eyes. | 0.911312 | 3.680504 |
This Legacy journal article was published in Volume 4, February 1994, and has not been
updated since publication. Please use the search facility above to find regularly-updated information about
this topic elsewhere on the HEASARC site.
The SAS-2 and COS-B
Paul Barrett & Brendan Perry
In Volume 5 of the `Annual Review of Astronomy and Astrophysics' (1967),
Giovanni Fazio wrote that "... up until now, no photons of energy greater than
100 keV originating from beyond the solar system have definitely been
detected." During the next few years, many groups using balloon-borne detectors
reported detections of gamma-ray sources. However, such experiments were
hampered by the high level of atmospheric gamma-rays due to cosmic ray
interactions in the atmosphere, making the statistical significance of such
sources low and their existence doubtful. Though several gamma-ray detectors
were placed in orbit, the first certain detection of celestial gamma-rays came
from OSO-3, which detected emission of gamma-rays with energies greater than 50
MeV from the galactic disk with a peak intensity toward the galactic center.
The first unambiguous detection of high-energy (>50 MeV) gamma-ray sources
was achieved with the SAS-2 satellite. Unfortunately, the lifetime of the SAS-2
mission was cut short after about six months by the failure of a low-voltage
power supply. The European Space Agency's COS-B satellite was the next major
high-energy gamma-ray detector. It's lifetime was considerably longer than
that of SAS-2 and was turned off after about 8 years when on-board resources
were exhausted. The second COS-B catalog containing the positions of 25
sources was the most complete listing of high-energy gamma-ray sources until
the recent release of the Compton/EGRET catalog (Fichtel et al. 1993).
Since the launch of the Compton Observatory in April 1991, there has been
renewed interest in the SAS-2 and COS-B data. For example, the data has been
used to check for long-term (of order years) variability of sources discovered
in the EGRET all-sky survey and to improve the ephemeris of the Geminga pulsar
(see e.g. Legacy, No.2) by extending its timeline. Therefore, HEASARC
has decided to make this data available publicly and this article may be
considered an announcement of its availability. The intention of this article
is to give an overview of the two datasets. Details of the restoration and FITS
formats for the data, and associated calibration data, can be found in other
OGIP documents located on the FTP server legacy (see the article in
Legacy, No.3 by Drake and O'Neel).
2. The SAS-2 Mission
The second NASA Small Astronomy Satellite (SAS-2) was dedicated to gamma-ray
astronomy in the energy range above 35 MeV. The satellite carried a single
telescope using a 32-level wire spark-chamber. The satellite was spin
stabilized with the telescope axis along the spin axis. SAS-2 was launched on
1972 November 15 and became operational on 1972 November 19. On 1973 June 8, a
failure of the low-voltage power supply ended the collection of data. During
the approximately six months of the mission, 27 pointed observations, typically
of a week duration, were made resulting in about 55 percent of the sky being
observed, including most of the galactic plane. The field-of-view of the
telescope is about 35 degrees (full width at half maximum) with an angular
resolution of a few degrees. In addition to the general galactic emission,
high-energy gamma-rays were also seen from the Crab and Vela pulsars (see e.g.
Fichtel et al 1975).
The low fluxes involved in the study of gamma-ray sources make it desirable to
minimize the background flux from cosmic-rays. Therefore a low Earth equatorial
orbit was chosen having a 2 degree inclination, an apogee and perigee of 610 km
and 440 km, respectively, and an orbital period of about 95 minutes. The
sensitivity of the sparkchamber was noticed to decrease during the lifetime of
the mission as the sparks from the gamma-ray event caused the gas to crack
producing unwanted by-products. Do to the degradation of the gas and the
inability to flush and replace it with new gas, the lifetime of the mission
would not have been more than about 9 months, in any case. The calibration of
the SAS-2 experiment was done using both the flight unit and an identical
flight spare unit. The range of energy studied at the National Bureau of
Standards (NBS) Synchrotron, Gaithersburg, Maryland, was approximately 20 to
114 MeV. The energy range between 200 to 1000 MeV was studied at the Deutsches
Elektronen-Synchrotron (DESY), Hamburg, West Germany.
The format of the SAS-2 data is based on a ROSAT Events FITS file. Briefly,
such a file contains a primary header and four extensions. No data is
contained in the primary header. All data resides in the four extensions which
are named ALLGTI, STDGTI, EVENTS, and TSI. The ALLGTI and STDGTI extensions
contain the exposure information. The ALLGTI gives the time interval when the
instrument was on and ready to receive data, whereas the STDGTI gives the time
interval when data, deemed to be good by the standard processing software, were
received by the instrument. Therefore, the total exposure from the STDGTI is
usually less than that from the ALLGTI. The EVENTS extension contains a list of
all the events for an observation, and the TSI extension is for the
housekeeping data or the instrumental status.
In order to restore fully the SAS-2 data (i.e.. provide event, exposure, and
housekeeping data), access to the original data was necessary. The SAS-2 event
list was commonly used by researchers, but the exposure information was never
made available. The original data provided us with the orbital parameters and
status of the spacecraft, from which we were able to calculate the necessary
exposure data and extract the auxiliary housekeeping data. Thus, for the first
time the SAS-2 data has been put into a form that is compatible with that of
COS-B and EGRET data. The SAS-2 data has been divided into 27 files, one for
each pointing. The total number of events that satisfied the trigger logic of
the spark-chamber and post-flight human and software selection was 13056.
In addition to the event data, calibration data also has been made available.
There are four types of calibration files: 1) the redistribution matrix or
energy dispersion data, 2) the effective area or sensitivity data, 3) the
point-spread-function data, and 4) the energy boundary data. The calibration
data was not available in the original data, but was gleaned from the
literature (see Fichtel et al. 1975). More detailed information about these
files can be obtained from the `SAS-2 Calibration Guide' in the legacy
3. The COS-B Mission
The European Space Agency's satellite COS-B was dedicated to gamma-ray
astronomy in the energy range 50 MeV to 5 GeV and carried a single experiment:
a spark-chamber telescope, developed by six European institutes in
collaboration. The experiment became operational on 1975 August 17 and was
switched off on 1982 April 25 when on-board resources were exhausted. During
this period, 65 observations, typically of a month's duration, were performed.
The satellite was spin-stabilized with the telescope axis along the spin axis.
Circular sky regions of about 40 degrees in diameter were covered in each
observation. The majority of the pointings were distributed along the galactic
equator, 15 observations were devoted to regions at high (>20 degree)
galactic latitudes. Several regions of specific interest were observed
The highly eccentric polar orbit of COS-B, with an apogee around 90,000 km
(chosen to maximize useful observation time while allowing real-time data
transmission) exposed the experiment to the solar modulated interplanetary
cosmic-ray flux. The unexpectedly long operational life of the experiment,
specifically of the spark-chamber, was accompanied by a long-term degradation
and by short-term disturbances of its performances and, consequently, of the
experimental sensitivity. The variation and sensitivity of the instrumental
background were investigated thoroughly and integrated into the database. The
possible impact of their statistical and systematic uncertainties must be
considered in any type of analysis.
The format of the COS-B data, like the previously discussed SAS-2 data, is
based on a ROSAT Events FITS file. The COS-B FITS files are based on the final
COS-B database (see H.A. Meyer-Hasselwander et al., 1986 for a detailed
description). The original database contained three files: the observation
file, the exposure file, and the event-list file, with indices in one file
pointing to records in another file. The design of this database is similar to
the extensions in a ROSAT Events FITS file, making the creation of the COS-B
FITS files easier than those of SAS-2. The completed database contains 65 files
corresponding to the 65 observation periods containing all of the exposure and
event information for that period.
During the processing of the data, we decided to scan each of the three
original files for data integrity. For the event-list file, we checked the
following parameters for their proper values (as described in the "Explanatory
Supplement to the COS-B Final Database" by H.A. Meyer-Hasselwander): gamma
class, edit class, photon energy, right ascension, and declination. We found
that some events have a `photon energy' of 0 MeV, a `declination' of +95
degrees and an `edit class' larger than three. These 750 events were obviously
not meaningful and were deleted from the database. Additionally, the `gamma
class' was found to have more than the three cases (2, 22, and 3) as specified
in the "Explanatory Supplement." Since the energy and coordinate of the event
was acceptable, these events were not deleted from the database. Details of
other minor discrepancies can be found in the "HEASARC COS-B Database
Document", which is currently in preparation.
4. Using the Data
The main reason for restoring the SAS-2 and COS-B datasets is to make them
available in a standard FITS format that is useful to the High Energy
Astrophysics community. The rationalized FITS format developed by the HEASARC
and the ROSAT Guest Observer Facility was adopted as the standard. The ROSAT
and ASCA missions are using this format as their standard and EGRET data also
will be translated into this format, as will most future HEA photon event data.
The availability of SAS-2, COS-B, and EGRET data in this format allows the data
to be imported easily into the IRAF/PROS software package and XANADU software
package, including XSELECT, a set of tasks for analyzing HEA data in FITS
In addition a program called FADMAP, which is based on a program of the same
name for analyzing COS-B data, will be made available soon. FADMAP produces
three maps or images: a background counts map, a source counts map, and an
exposure map. A fourth map, a flux map, is produced from these three maps. By
using FTOOLS tasks, it will be possible to combine data from SAS-2, COS-B, and
EGRET into a FITS file that then can be read into FADMAP or any of the other
previously mentioned data analysis software.
The data are currently available via HEASARC's anonymous ftp account and are
located in the public directories, cosb/ and sas2/, on the
host, legacy.gsfc.nasa.gov (18.104.22.168). Each directory contains
several subdirectories, data/, doc/, and
calib_data/, along with .message and README files
describing the contents and status of the directory. The calib_data/
subdirectory also has several subdirectories including a doc/
subdirectory that currently contains LaTeX and PostScript files of the SAS-2
and COS-B Calibration Guide.
Access to these data is possible via anonymous ftp or Gopher. For more
information about using ftp or Gopher to access the HEASARC anonymous ftp
account, see the article by Drake et al. in this issue of Legacy.
5. Future Directions
The SAS-2 and COS-B FITS files may undergo some revision in the future to make
the data more accessible to the high-energy astrophysics community, though we
expect these changes to be minor. Aspects that may affect these changes are:
1) the compatibility of the two datasets with each other. Because SAS-2 and
COS-B were different instruments from different experimental groups, the event
data and housekeeping data were likewise different. Some incompatibility still
exists between the two datasets mostly due to differences of the housekeeping
data. Such changes may be resolved in the future allowing data analysis
software to access the data in a more consistent manner.
2) the compatibility of the two datasets with the Compton Gamma-Ray Observatory
Science Support Center's data analysis software. Some of the data analysis
software is designed to analyze EGRET data. Changes to the SAS-2 and COS-B FITS
files also would allow this data to be analyzed using the same data analysis
In a future issue of Legacy, we plan to describe how to use the tasks
available in the XANADU software package, including FADMAP, to analyze the
COS-B and SAS-2 data.
"The HEASARC's Newly Consolidated Anonymous FTP Account", 1993, S. Drake &
B. O'Neel, Legacy, 3, 53.
"Gamma Radiation from Celestial Objects", 1967, G.G. Fazio, , Ann. Rev.
Astr. Ap., 5, 481.
"High-Energy Gamma-Ray Results from the Second Small Astronomy Satellite",
1975, C.E. Fichtel, R.C. Hartman, D.A. Kniffen, D.J. Thompson, G.F. Bignami, H.
Ogelman, M.E. Ozel, & T. Tumer, Ap. J., 198, 163.
"First Energetic Gamma-Ray Experiment Telescope Catalog",1993, C.E. Fichtel et
al. , Ap. J. Supp., submitted.
"Explanatory Supplement to the COS-B Final Database", 1986, H.A.
MeyerHasselwander et al., in Proc. Cosmic Ray Conf., La Jolla, ESA
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Most days in 1892, ticketholders at Manhattan’s Carnegie Music Hall enjoyed programs of standard entertainment: the New York Philharmonic; a famous speaker; a ragtime show. But starting in February, every Monday, Wednesday, and Saturday, they got something a little different. As soon as the theater’s lights went down, the sun came up again, rising over an onstage lake that rippled just like the real thing. Next, the moon began to rise next to the sun, and gradually, dramatically obscured it. This was Scene #1 of A Trip to the Moon—a perfect rendition of the total solar eclipse of 1887, yanked through time and space and reconstructed inside the theater.
“Audiences had, in a sense, seen it all,” writes the media scholar Artemis Willis. But when curtain lifted on A Trip to the Moon’s first scene, “their cynicism yielded to wonder.” Over the next 90 minutes, viewers were treated to a number of rare and, at the time, impossible sights: lunar landscapes, cosmic nebulae, the earth as viewed from the moon, and more, all produced through an alchemy of stagecraft, lighting, and special effects. By the time they rose from their seats, Willis argues, they had absorbed not only facts and figures, but a whole new way of looking at space.
As Willis details in a recent paper about the show, A Trip to the Moon was first dreamed up in 1889, at the Urania Institute in Berlin. Unlike most observatories at the time, which had their hands full catering to experts, the Institute focused on curious laypeople—what one admirer, the astronomer Edward Holden, described as “that very large and intelligent section of the public which is intensely interested in the results of astronomical observation… but does not care at all for the small details which the special student must attend to.”
As part of these efforts, the Institute put together a number of stage presentations, which taught attendees about everything from the geological birth of Earth to the tides and currents of the Arctic Ocean. The shows proved extremely popular, and when word of them reached Andrew Carnegie, he decided to bring one or two over to New York City and stage them in his brand new Music Hall. “Mr. Carnegie’s idea is to discover whether there is real demand for such institutes in America, and to assist in founding them, if there is,” wrote Holden.
The Berlin version of the show was already a multimedia marvel, but for its own trip to the Music Hall—about seven times the size of the theater at the Urania Institute—A Trip to the Moon got even more gussied up. Larger versions of the set pieces were painted in Berlin and shipped over, and the staging took full advantage of the Music Hall’s recent renovations, during which the venue had been outfitted with electrical wiring and lighting.
Every scene involved what Willis calls an “electro-mechanical-theatrical tableau,” in which stage lights waxed, waned, and changed colors, magic lanterns projected scenes onto set pieces, and backstage crew members put various props through complex paces. Plus, it was all accurate: “Each move of the moon was charted to accurately reflect the phenomena, and then choreographed behind the scenes,” says Willis. “It would be really difficult to pull off such a performance today.”
For example, the climactic “Scene #6: Solar Eclipse as Seen from the Moon,” involved three celestial bodies, each differently positioned, and all interacting with one another. As illustrated at the top of this article, the moon—the scene’s vantage point—was represented by a painted canvas, lit from underneath by electric footlights. The sun was a lightbox sewn into a black drop cloth (which also had holes pricked in, for stars), and the earth was a phosphorescent disk with a ring of red gelatin around it. In the scene, the sun slowly crosses behind the earth, backlighting the gelatin and suffusing the stage with a red glow. The footlights below the canvas then gradually change to red, “transferring” the light of the eclipse to the moon’s surface.
A Trip to the Moon premiered on February 10, 1892, to an intrigued audience. But after a week and a half of lukewarm reviews, the production took the step that, in Willis’s view, really put it over the top: it went in for a script rewrite. The original narration, written by the Urania Institute’s Max Wilhelm Meyer and performed by a wide-eyed actor, “was sort of clunky and romantic,” Willis says. “The New York press picked up on that right away.”
As one New York Times critic wrote, the “Wagnerian drama” didn’t play well with this particular audience: “The lecture is heralded as gravely as if it were a new religion just discovered,” they wrote. “The audience is edified so gradually that there is more awe than comfort in it.”
The producers went out looking for a script doctor, and settled on Garrett P. Serviss, an astronomy columnist for the New York Sun. Over the course of nine days, Serviss rewrote the narration completely; when the show re-opened, he had taken on hosting duties as well. The result was a Trip to the Moon that, a happier Times critic wrote, was led “by someone who knew the way.” Where Meyer had spun grandiose tales, Serviss provided plainspoken explanations, grounded in facts. For example, during Scene #6, Serviss laid out exactly what was going on:
“Such an eclipse would present phenomena far different from those which we behold during a solar eclipse upon the earth. The most remarkable difference would be that arising from the fact that the earth is enveloped in air. The atmosphere of the earth, owing to its refractive property, acts like a lens surrounding the terrestrial globe, and bends the sunlight around its edge.
So, when the sun disappears behind the earth as seen from the moon, a brilliant circle of light girds the earth, and this light… produces a considerable illumination on the moon. The color of the luminous ring encircling the earth, under these circumstances, will be that of the sunrise and sunset sky, because the light has to penetrate the dust and vapor floating in the air, and the red rays most easily accomplish the passage.”
Compare this, Willis says, to Meyer’s version of the scene, in which the Earth is referred to as “the moon’s astral mother,” and its light as “the only agency of communication that is still left to her,” sent through space “a last greeting to her only daughter, lost so early in death.”
A hobbyist astronomer himself, Serviss also made sure to foreground the concerns of actual experts. “He would try to find ways to help his audiences imagine our relation to the cosmos as investigators of it,” says Willis. “[He was] encouraging a kind of mind travel, [as with the] ‘Spaceship of the Imagination’”—a device Carl Sagan used, in his seminal television show Cosmos, to represent the possibilities of scientific inquiry.
A Trip to the Moon played at the Music Hall for just over two years, and then did a short tour of the East Coast. Its creators went on to successful careers: Serviss began lecturing full-time (and later established himself as a prolific science fiction author), and the show’s lighting designer, J. Carl Mayrhofer, started his own company.
But in Willis’s reading, the show left another legacy: the ability for ordinary people to look at the heavens with something more than slack-jawed awe. Where earlier astronomical entertainments, including Meyer’s original A Trip to the Moon, leaned into astronomy’s reputation as “the sublime science”—full of proof of God’s limitless power, and humanity’s infinite smallness—A Trip to the Moon replaced some of that void-staring with curiosity. “It didn’t just say, ‘This is God’s great work, be afraid of it,’” says Willis. “It described the phenomena in terms that produced wonder.”
“The information was as new as possible, and the technology was as new as possible,” she says. “That’s where I think wonder was produced: in the space between the actual lunar phenomena, and the enactment of them.” As with an eclipse, in which the juxtaposition of the sun and the moon makes each more magnificent, A Trip to the Moon made knowledge and its representation dance around each other, equal at last. | 0.824091 | 3.092693 |
Instrumentsaboard the VenusExpress spacecraft have obtained the first large-area temperature map ofthe southern hemisphere of Venus'searing surface.
Byidentifying hot spots on this inhospitable planet, the new data--obtained by theVisible and Infrared Thermal Imaging Spectrometer (VIRTIS)--could spot active volcanism.
VIRTIS lookedthrough the thick carbon dioxide curtain surrounding Venus and detected theheat directly emitted by the hot rocks on the ground. The instrument made useof the so-called infrared spectral "windows" present in the Venusianatmosphere. Through these windows thermal radiation at specific wavelengths canleak from the deepest atmospheric layers, pass through the dense cloud curtain,and then escape to space, where it can be detected.
On Venusthere are no day and night variations of the surface temperature. The heat isglobally trapped under a thick carbon-dioxide atmosphere, with pressure 90times higher than on Earth. Instead, the main temperature variation is due totopography.
Just likeon Earth, mountain tops are cooler, whereas the lowlands are warmer. The onlydifference is that on Venus cold means 837 degrees Fahrenheit (447 degreesCelsius), while warm means 891 degrees Fahrenheit (477 degrees Celsius). Suchhigh temperatures are caused by the strongest greenhouseeffect found in the Solar System.
The VIRTISresults represent a major step forward in our attempt to identify specific featureson the surface of Venus, said J?rn Helbert from the German Aerospace Center's (DLR) Institute of Planetary Research in Berlin, Germany. "By peelingoff the atmospheric layers from the VIRTIS data, we can finally measure thesurface temperature."
Theresearchers hope to identify volcanoes on the surface of Venus. In the SolarSystem, besides Earth, activevolcanoes have been observed only on Io, a satellite of Jupiter, on Neptune's satellite Triton,and on Saturn's moon Enceladus.Venus is the most likely planet to host other active volcanoes.
Thefindings were presented today at the annual fall meeting of the AmericanGeophysical Union in San Francisco.
- Venus and Earth: Worlds Apart
- Hot Discovery: Dark Vortex on Venus
- European Probe Reaches Final Orbit Around Venus
- Images: Below the Clouds of Venus | 0.84487 | 3.991227 |
The galaxy that we live in is indeed quite a wonderful thing. Take a look around the world that we inhabit, and things like the solar system immediately feel very interesting indeed. All it takes is a quick look around to help you see that we are very much in a vast expanse of space, with so much to be found. Recent probes and studies, though, found what is being called “Farout” – the single further object we’ve found in our solar system.
This latest discovery comes after a team of international astronomers found the object located around 11.15 billion miles from the sun. This small, rounded object sits around 17.95 billion km away, then, and currently carries a rich, pink hue. The discovery was made using the Las Campanas Observatory in Chile.
310 miles in diameter, this interesting discovery is a landmark moment as it becomes the first object discovered to be more than 100 Astronomical Units (AU) from our own star. For reference, 1 AU is the distance from the Earth to the Sun. in total, this sits around 120 AU, while our furthest find yet until now was Eris the dwarf planet found at around 96 AU.
If you want a good example of just how far this is, Pluto is around 34 AU!
It’s also very interesting as it brings us into contact with something much further out than Pluto. It would be something very interesting to hear more about, especially as the orbits of these objects appear to be influenced via the gravity of a large-scale planet. Some, then, estimate that this could be the infamous Planet 9 which could, in theory, sit as far back as 200 AU from the Sun.
Speaking about this was co-discoverer Scott Sheppard, part of the Carnegie Institution for Science, who said: “2018 VG18 is much more distant and slower moving than any other observed Solar System object, so it will take a few years to fully determine its orbit.
But it was found in a similar location on the sky to the other known extreme Solar System objects, suggesting it might have the same type of orbit that most of them do. The orbital similarities shown by many of the known small, distant Solar System bodies was the catalyst for our original assertion that there is a distant, massive planet at several hundred AU shepherding these smaller objects.”
While this might just be one smaller discovery, it does create much excitement about what we might find if we continue to look further beyond our present limits.
We want to be better...So if you found a mistake in this article, please let us know | 0.842186 | 3.683393 |
NASA's Kepler Mission uses transit photometry to determine the frequency of Earth-size planets in or near the habitable zone of Sun-like stars. The mission reached a milestone toward meeting that goal: the discovery of its first rocky planet, Kepler-10b. Two distinct sets of transit events were detected: (1) a 152 4 ppm dimming lasting 1.811 0.024 hr with ephemeris T[BJD] =2454964.57375 +0.00060 -0.00082 + N*0.837495+0.000004 -0.000005 days and (2) a 376 9ppm dimming lasting 6.86 0.07 hr with ephemeris T[BJD] =2454971.6761+0.0020 -0.0023 + N*45.29485+0.00065 -0.00076 days. Statistical tests on the photometric and pixel flux time series established the viability of the planet candidates triggering ground-based follow-up observations. Forty precision Doppler measurements were used to confirm that the short-period transit event is due to a planetary companion. The parent star is bright enough for asteroseismic analysis. Photometry was collected at 1 minute cadence for >4 months from which we detected 19 distinct pulsation frequencies. Modeling the frequencies resulted in precise knowledge of the fundamental stellar properties. Kepler-10 is a relatively old (11.9 4.5Gyr) but otherwise Sun-like main-sequence star with T eff = 5627 44K, M = 0.895 0.060 M, and R = 1.056 0.021 R. Physical models simultaneously fit to the transit light curves and the precision Doppler measurements yielded tight constraints on the properties of Kepler-10b that speak to its rocky composition: M P = 4.56+1.17 -1.29 M ⊕, R P = 1.416+0.033 -0.036 R ⊕, and ρP = 8.8+2.1 -2.9gcm-3. Kepler-10b is the smallest transiting exoplanet discovered to date.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science | 0.82566 | 3.834566 |
“Two Russians, a Finn, and a Jew come into a bar” seems like the beginning of a joke. In fact, it is really “two South Africans, a Russian and an Israeli go into the SALT dome”, and this is not a joke. Observations performed at SALT and analyzed by an international team spanning 2.5 continents (Africa, Europe, and the Middle East) revealed the true nature of a rare and intriguing galaxy, a ring that is a nice celestial jewel. The results are reported in a paper just published by the Monthly Notices of the Royal Astronomical Society: http://adsabs.harvard.edu/abs/2015MNRAS.451.4114B.
When we think of “jewelry” what comes to mind are gold or silver rings studded with diamonds and other precious stones. These tiny adornments fetch huge prices at public sales, but they are not the most beautiful rings astronomers know of. One particularly interesting kind of galaxy looks just like such a jewelry piece; a ring of stars and gas that shine brightly in the darkness of the Universe. The empty ring studied in our paper is tens of thousands of light-years across. Astronomers do not yet know how such galaxies are formed and into which form will they evolve; this is the reason to study this specific celestial ring.
The galaxy analyzed in the paper has no catchy name; the scientific community knows it only by a catalog number: ESO 474-G040. It belongs to the fascinating class of empty ring galaxies, very much different from our Milky Way (a mundane spiral) or from M87 (a giant elliptical galaxy), or even from our nearest neighbor galaxies the Magellanic Clouds.
Telescopic images present to the observer a ring whose width is about one minute of arc; at its leading listed redshift, which puts the galaxy a bit more than one billion light-years away, the ring would have to be about 400,000 light-years wide. This is 30 times larger than our own Milky Way and would imply that ESO 474-G040 could be the giant among ring galaxies, the “one ring to rule them all”.
Empty ring galaxies are known but are also very rare. Generally, they are the size of a normal galaxy. It is believed that they could form from a head-on collision between to disk galaxies, although other mechanisms have also been proposed. The general impression is also that ring galaxies are currently forming stars, partly or mostly because of the collision; this compresses the gas between the stars, which then turns into new stars that are hot and bright, and which ionize the gas not yet morphed into stars. Numerical simulations show that ring galaxies are generally unstable and disrupt after about one billion years, or maybe less.
Our study benefited from both the large collecting area of SALT that allowed the production of very deep images using the telescope’s SALTICAM camera, and of the exquisite spectroscopic tools on SALT that split the light collected by the telescope into different wavelengths, allowing the determination of the galaxy’s dynamics and of its stellar composition. These tools are part of the Robert Stobie Spectrograph (RSS). One is its long-slit option that analyzes the light in a wide spectral window that is coming through a narrow and long opening, by splitting it into many wavelength slices aligned onto a line passing through the galaxy, with each slice being some 200 km/sec wide.
The RSS can, via a special attachment, provide also a two-dimensional “image” of the velocity field of the ionized gas. This attachment, called a “Fabry-Pérot interferometer”, splits the images by wavelength into sub-images that are only a few km/sec wide. Analyzing such images can show whether the ring is rotating, expanding or contracting. The long-slit yielded a revision of the ring’s distance from its recession velocity, and allowed the determination of the stellar populations in the sampled areas.
The SALTICAM images show that the center of the ring is empty, i.e. there is no “projectile” or remains of a possible collider galaxy; lacking an iris means that this object is not “the eye of Sauron”, as some might want to. The long-slit RSS observations brought about a downward revision of the galaxy’s distance and physical size; these shrank by a factor of five, bringing the size of the ring into the “normal” galaxy size range. However, the most important results came from combining the long-slit and Fabry-Pérot RSS data to derive the kinematic properties. The ring itself rotates just as would do a disk or spiral galaxy of this size and mass and is neither contracting nor expanding. The analyzed parts of the ring contain stars that are a few hundred million years, or even a billion years old, but also very recently-formed stars. The most likely explanation for this strange galaxy is that it formed from the merger of two disk galaxies, where material pulled out of the galaxies by the tidal force formed the ring, which is subsequently breaking up into beads, some containing very young star clusters.
The team that observed and analyzed ESO 474-G040 is composed of Petri Väisänen and Alexei Kniazev from SAAO, Alexei Moiseev from the Special Astrophysical Observatory, Russian Academy of Sciences, and Noah Brosch from Tel Aviv University in Israel. The team collaborated previously in projects using SALT and the Russian 6-m telescope, for instance in understanding elliptical galaxies with dust lanes, or galaxies with external rings.
Monthly Notices of the Royal Astronomical Society: http://adsabs.harvard.edu/abs/2015MNRAS.451.4114BИсточник | 0.801275 | 3.750632 |
When a massive star runs out fuel, it collapses and explodes as a supernova. Although these explosions are extremely powerful, it is possible for a companion star to endure the blast. A team of astronomers using NASA's Chandra X-ray Observatory and other telescopes has found evidence for one of these survivors.
This hardy star is in a stellar explosion's debris field - also called its supernova remnant - located in an HII region called DEM L241. An HII (pronounced "H-two") region is created when the radiation from hot, young stars strips away the electrons from neutral hydrogen atoms (HI) to form clouds of ionized hydrogen (HII). This HII region is located in the Large Magellanic Cloud, a small companion galaxy to the Milky Way.
A new composite image of DEM L241 contains Chandra data (purple) that outlines the supernova remnant. The remnant remains hot and therefore X-ray bright for thousands of years after the original explosion occurred. Also included in this image are optical data from the Magellanic Cloud Emission Line Survey (MCELS) taken from ground-based telescopes in Chile (yellow and cyan), which trace the HII emission produced by DEM L241. Additional optical data from the Digitized Sky Survey (white) are also included, showing stars in the field.
R. Davies, K. Elliott, and J. Meaburn, whose last initials were combined to give the object the first half of its name, first mapped DEM L241 in 1976. The recent data from Chandra revealed the presence of a point-like X-ray source at the same location as a young massive star within DEM L241's supernova remnant. (Mouse over the image to see the location of the survivor companion star.)
Astronomers can look at the details of the Chandra data to glean important clues about the nature of X-ray sources. For example, how bright the X-rays are, how they change over time, and how they are distributed across the range of energy that Chandra observes.
In this case, the data suggest that the point-like source is one component of a binary star system. In such a celestial pair, either a neutron star or black hole (formed when the star went supernova) is in orbit with a star much larger than our Sun. As they orbit one another, the dense neutron star or black hole pulls material away its companion star through the wind of particles that flows away from its surface. If this result is confirmed, DEM L241 would be only the third binary containing both a massive star and a neutron star or black hole ever found in the aftermath of a supernova.
Chandra's X-ray data also show that the inside of the supernova remnant is enriched in oxygen, neon and magnesium. This enrichment and the presence of the massive star imply that the star that exploded had a mass greater than 25 times, to perhaps up to 40 times, that of the Sun.
Optical observations with the South African Astronomical Observatory's 1.9-meter telescope show the velocity of the massive star is changing and that it orbits around the neutron star or black hole with a period of tens of days. A detailed measurement of the velocity variation of the massive companion star should provide a definitive test of whether or not the binary contains a black hole.
Indirect evidence already exists that other supernova remnants were formed by the collapse of a star to form a black hole. However, if the collapsed star in DEM L241 turns out to be a black hole, it would provide the strongest evidence yet for such a catastrophic event.
What does the future hold for this system? If the latest thinking is correct, the surviving massive star will be destroyed in a supernova explosion some millions of years from now. When it does, it may form a binary system containing two neutron stars or a neutron star and a black hole, or even a system with two black holes.
A paper describing these results is available online and was published in the November 10, 2012 issue of The Astrophysical Journal. The authors are Fred Seward of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA; P. Charles from University of Southampton, UK; D. Foster from the South African Astronomical Observatory in Cape Town, South Africa; J. Dickel and P. Romero from University of New Mexico in Albuquerque, NM; Z. Edwards, M. Perry and R. Williams from Columbus State University in Columbus, GA.
NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Mass., controls Chandra's science and flight operations. | 0.859793 | 4.131951 |
Could Life on Earth Have Come From Ceres?
The Hubble Space Telescope can only make out vague surface features on Ceres.
Image credit: NASA, ESA, J. Parker (Southwest Research Institute), P. Thomas (Cornell University), and L. McFadden (University of Maryland, College Park).
Astrobiologists hope to find life elsewhere in the universe, or possibly even in our own cosmic neighborhood, the solar system. Their efforts are usually concentrated on worlds such as the planet Mars, or icy moons like Europa. However, there are other, less conventional locations in the solar system where scientists think life may be found.
Ceres: an unusual choice
At the International Society for the Study of the Origin of Life conference in Florence, Italy, Joop Houtkooper from the University of Giessen divulged a theory that life could have originated on an object in the asteroid belt named Ceres. Ceres was considered to be a planet when it was discovered in 1801, but it was later downgraded to asteroid status. With the latest planet definition from the International Astronomical Union, the round object is now considered a dwarf planet. Is there a chance that this exotic world is home to extraterrestrial organisms?
“This idea came to me when I heard a talk about all the satellites in the solar system that consist of a large part of ice, much of which is probably still in a liquid state,” says Houtkooper. “The total volume of all this water is something like 40 times greater than all the oceans on Earth.”
This reminded Houtkooper of a theory about how life originated. Organisms may have first developed around hydrothermal vents, which lie at the bottom of oceans and spew hot chemicals. Many icy bodies in our solar system have rocky cores, so they may have had or still have hydrothermal vents. Houtkooper realized, “if life is not unique to the Earth and could exist elsewhere, then these icy bodies are the places where life may have originated.”
Looking at the evidence
Early in the history of the solar system was a period known as Late Heavy Bombardment, a turbulent time when cataclysmic asteroid impacts were common. If there was life on Earth before this dangerous era, it was most likely eradicated and had to begin again after much of this cosmic debris had cleared out of the inner solar system. Interestingly, evidence indicates that Ceres avoided being pummelled by devastating impacts during this time. If it had been bombarded, it would have completely and forever lost its water mantle, as its gravitational force is too weak to recapture it. This is probably what happened to the asteroid Vesta, which has a very large impact crater and no water.
Ceres is a varied world which could host life.
Image credit: NASA, ESA, and A. Feild (STScI)
“The evidence points to Ceres having remained relatively unscathed during the Late Heavy Bombardment,” states Houtkooper. He says this means Ceres still could have “a water ocean where life could have originated early in the history of the solar system.”
This leads to an interesting hypothesis. If the Earth was sterilized by colossal impacts, but Ceres hosted life which survived, could the dwarf planet have reseeded our world with life, via rock fragments that chipped off Ceres and then crashed into Earth? Are all organisms on Earth, including humans, descendants of Ceres? This is an idea that Houtkooper had to pursue.
“I looked at the different solar system bodies which either had or currently have oceans,” he explains. “The planet Venus probably had an ocean early in its history, but the planet’s greater mass means that more force is needed to chip off a piece of the planetary crust and propel it in the direction of the Earth. Smaller objects like Ceres have lower escape velocities, making it easier for parts of it to be separated.”
Houtkooper then calculated the orbital paths of candidate planets, moons and asteroids to see which were in the best positions to have pieces successfully reach the Earth, without being intercepted by other objects. Ceres fared favourably in these calculations.
Life on Ceres
Relative sizes of the Earth, our Moon, and Ceres.
Finally, Houtkooper considered the possibility of organisms still being present on Ceres. “In the ocean, there could be life,” he suggests. “On the surface, it would be more difficult. But there are some possibilities. There could be hydrogen peroxide-based life, able to withstand the low temperatures.” It’s not currently known whether hydrogen peroxide is present on Ceres, but nothing rules it out, either.
The thought of Earth being seeded with life from Ceres and creatures existing there today is certainly fascinating, but Houtkooper admits that it is more science fiction than science fact until evidence can be provided. This is naturally difficult to obtain, as Ceres is a small and distant world. Even the best current images contain very little detail, and just show that there are some surface features; what these features are exactly is a mystery. Spectral analyses indicate the presence of clay-like minerals, and Ceres’ slightly flattened shape is what we would expect from a world with a rocky core below a layer of water or ice. Ceres is a dwarf planet with many secrets.
Fortunately, this will soon change thanks to NASA’s DAWN mission. Launched in 2007, the probe is due to arrive at Ceres in 2015. Once there it will shed light on the mysterious world, and perhaps take photographs of geysers of water erupting from the surface. Its close-up view could indicate whether Ceres really does have the potential for life. | 0.899866 | 3.866603 |
Panchromatic astronomy on a budget
by Jeff Foust
|“Hubble is in good technical condition and is right now, even after 30 years, at the peak of its scientific return,” said Wiseman.|
To confirm TOI 700 d was a real planet, astronomers turned to another, venerable spacecraft: the Spitzer Space Telescope. “We wanted to be absolutely sure that this was real as well as really refine our understanding of the planet,” said Joseph Rodriguez, an astronomer at the Center for Astrophysics (CfA) | Harvard & Smithsonian, during the briefing. Those observations by Spitzer confirmed the planet was real and helped constrain its orbit and size, he said, adding that Spitzer performed another observation of the planet as it transited in front of its star just the day before the briefing.
But Spitzer’s days are coming to an end. On January 30, NASA will transmit the final commands to the space telescope, instructing it to shut down. Launched in 2003 into a heliocentric orbit, NASA announced last year it would shut down the spacecraft because of its age, and complications with communications and spacecraft operations as the spacecraft’s distance from the Earth increases. (NASA briefly considered handing over Spitzer operations to a private organization who would cover the costs of doing so, but none with both the interest and the budget stepped up.)
Spitzer, originally known as the Space Infrared Telescope Facility, was the last of NASA’s original four “Great Observatories” to launch. The Compton Gamma Ray Observatory, launched in 1991, deorbited in 2000 after suffering failures of several of its gyroscopes. That leaves the Chandra X-Ray Observatory and the Hubble Space Telescope as the two surviving Great Observatories after this month.
Both Chandra and Hubble are getting old, though: astronomers marked the 20th anniversary of Chandra’s launch last year, while the 30th anniversary of Hubble’s launch is this April. Both are operating well, but have suffered technical glitches in recent years that, at the very least, are a reminder that neither will be around forever.
“The observatory is in great shape, even today,” said Jennifer Wiseman of NASA’s Goddard Space Flight Center about Hubble during a seminar about the telescope’s upcoming 30th anniversary at the AAS meeting. “Hubble is in good technical condition and is right now, even after 30 years, at the peak of its scientific return.”
Wiseman and other astronomers expect—or at least hope—that Hubble will continue to operate well into the 2020s. Three of Hubble’s six gyros have failed, but Wiseman said the three that failed are all of the same design while the other three are of a different design that appears to be longer lived. The spacecraft, she added, could operate on just a single gyro.
“We don’t know how long Hubble is going to last, but as long as Hubble is being scientifically productive, NASA is, at least now, committed to supporting it,” she said.
|“I don’t think that NASA should do just one of these missions. I think we should do all of these of these missions. These are our next Great Observatories,” said Hertz.|
There are, of course, new space telescopes in development. The long-delayed James Webb Space Telescope is set to launch in March 2021, while the Wide-Field Infrared Survey Telescope (WFIRST) will follow in 2025. Both those spacecraft, though, are optimized for observation in the infrared. Hubble, Wiseman argued, is “critically complementary” to those new space telescopes given its ability to observe at visible and ultraviolet wavelengths.
An illustration of the larger variant of LUVOIR, one of the large space telescope missions under consideration in the 2020 astrophysics decadal survey. (credit: NASA)
Another flagship space observatory could start development later this decade. NASA commissioned studies for four concepts, spanning the electromagnetic spectrum—HabEx, LUVOIR, Lynx, and Origins Space Telescope—that were completed last year and provided to the National Academies committee working on the latest astrophysics decadal survey, called Astro2020 (see “Selecting the next great space observatory”, The Space Review, January 21, 2019). That committee’s final report, due in about a year, will likely select one of those mission concepts as the top-priority flagship mission for the next decade, recommending that NASA fund its development.
Those concept studies have won high praise in the community for advancing the maturity of those proposed missions to a far greater degree than concepts proposed for previous decadal surveys. Some astronomers have suggested that the four missions band together as a sort of “New Great Observatories,” seeking the eventual development of all four.
“I don’t think that NASA should do just one of these missions. I think we should do all of these of these missions. These are our next Great Observatories. These are the missions we need to continue the multi-wavelength astrophysics that we have all grown used to over the last 30 years,” Paul Hertz, director of NASA’s astrophysics division, said during a NASA town hall meeting at the AAS conference. “I’m hopeful we can continue working on all of them so that we can launch them in series.”
Doing so, though, will take time. A “wedge” in NASA’s astrophysics budget for the next flagship mission will only start to open up towards the middle of the decade, as WFIRST nears launch. Hertz estimates that there’s about $5 billion a decade available for flagship missions, or perhaps $7 billion given more optimistic projections of the agency’s budget. Most in the field don’t expect that the mission that is selected as the top priority by Astro2020 to fly before about the mid-2030s, given those budget constraints. Both Chandra and Hubble may be defunct by then.
A report last year by a NASA science analysis group examined the potential gaps in wavelength coverage caused by the eventual demise of the original Great Observatories. Was that multi-wavelength, or “panchromatic,” coverage offered by the Great Observatories still important today? And, if so, how could it be maintained?
The answer to that first question was a clear “yes.” In the report, and a session about it at the AAS conference, astronomers discussed how having infrared, visible, ultraviolet, X-ray, and gamma-ray observations can work in conjunction in fields from exoplanets to galactic evolution to fundamental properties of the universe.
“A lot of the galactic science that we want to push forward in the next decade will require multiple wavelengths,” said Massimo Marengo of Iowa State University. “Also, we require it to be there at the same time so we can combine observations.”
|“Commensurate and concurrent capabilities can be achieved with a range of mission sizes and costs,” said Armus. “If you’re smart, you can do it with a mix.”|
A gap in that panchromatic coverage can have repercussions beyond the science itself. “There’s a community cost, too,” said Martin Elvis of the CfA. Such a gap discourages students from entering the field, creating a loss of “implicit knowledge” as those currently in the field retire without passing it on to a new generation. It would also discourage people from developing more advanced instruments, he said, since there would be no opportunity to fly them.
“It leads to a greater science cost yet,” he concluded. “You’ll basically be shutting down large areas of astrophysics.”
The report’s recommendation to address the science and community problems created by a gap wasn’t to simply build new flagship space telescopes. “At current funding levels, NASA clearly cannot develop three ~$9B strategic missions simultaneously in the next decade, or even two,” the report acknowledged.
Instead, it called for a mix of both flagships and smaller missions, a combination it dubbed the “Giant Leap Observatories.” That approach offers a more affordable way of providing some degree of panchromatic coverage while fitting into realistic budget scenarios at NASA.
“Commensurate and concurrent capabilities can be achieved with a range of mission sizes and costs,” said Lee Armus of Caltech, co-chair of the study. “If you’re smart, you can do it with a mix.”
As the report noted, not all of the Great Observatories would be considered flagship-class missions today. The report estimated that Hubble cost, at the time of its launch, $9.2 billion in 2019 dollars, about the same cost as JWST. Chandra, though, cost just $3 billion in 2019 dollars, a little less than the current $3.2 billion cost cap for WFIRST. And Compton and Spitzer cost just $1.2 and $1 billion, respectively, about the same as a “probe-class” astrophysics mission.
There is interest in NASA in pursuing a probe-class mission in parallel with JWST and WFIRST. NASA commissioned ten studies of probe mission concepts that, like the ones for the flagship missions, will feed into the Astro2020 decadal survey. Hertz said that NASA’s future budget projects include a funding wedge starting in 2022 for a probe, if the decadal recommends the development of one or more such missions.
Hertz, in another session of the AAS conference, lamented the fact that the 2010 decadal survey didn’t recommend a medium-class mission. “I was personally disappointed” the decadal didn’t endorse such a mission, he said, arguing that, early in the decade, there would have been agency support for it. “If a probe had been recommended in the 2010 decadal survey, we would have been allowed to start it right away. It would have launched by now.”
Those involved in the report on the Giant Leap Observatories concept hope to see some sort of consensus emerge in the broader astrophysics community for implementing its recommendations, perhaps with the Astro2020 report. “We should all get on the same page for developing a grand plan to carry out panchromatic science that we need,” said Stephan McCandliss of Johns Hopkins University.
Until then, astronomers are planning for a future without two of the four Great Observatories. While Spitzer’s infrared capabilities will ultimately be replaced, and greatly improved upon, by JWST and WFIRST, the end of Spitzer will leave some astronomers, like CfA’s Rodriguez, without many other options in the near term.
Asked at the press conference how he and colleagues would have confirmed TOI 700 d without Spitzer, Rodriguez said they had only a few other options, like the European Space Agency’s newly launched Characterizing Exoplanets, or Cheops, spacecraft. “That just shows the power of what Spitzer was able to do,” he said. “It is a bit limited without Spitzer, and I think that’s a key thing to make clear.”
Note: we are temporarily moderating all comments submitted to deal with a surge in spam. | 0.850019 | 3.089348 |
During the next week, Venus, the most brilliant planet, will rendezvous with two bright objects. First, on the evening of Monday, July 9, it will slide past one of the 21 brightest stars in the sky. Then, on Sunday evening (July 15), it will make for an eye-catching sight with the moon.
The first celestial meeting will be when Venus aligns with the blue-white star Regulus, the brightest star of the constellation Leo, the Lion. Six stars in Leo form a large backwards question-mark shape, popularly known as the Sickle. Regulus is at the end of the handle. It was one of the four "royal stars" which were supposed long ago to rule over the four quarters of the heavens. On the list of the 21 brightest stars, Regulus is number 21, but at least it's on the list.
Silvery white Venus and blue-white Regulus will be 3 degrees or less apart from July 7 through July 12 and will be closest – just one degree apart – on July 9. On July 8 we see them side by side, Venus on the right, Regulus on the left. On July 9, they're somewhat closer with Venus to the upper right of Regulus. On July 10, the gap between them will be a little wider, with Venus sitting directly above Regulus. [Skywatcher Photos: Dazzling Views of Venus & the Moon]
Look low toward the west around 9:45 p.m. local time. In late twilight, both the planet and star will be readily visible to the unaided eye. The difference between the two is considerable: Venus will outshine Regulus some 158 times; binoculars will enhance the view.
Venus and the moon
Then, on July 15, comes the second meeting, this time with the moon. The moon will be 3.5 days past new phase; a slender crescent just 12 percent illuminated, sitting to the right of Venus. For those in the eastern U.S., they'll be separated by just over 2 degrees by mid-twilight. But for those in the western U.S., the view will be more striking, because they'll appear half as far apart.
Regardless, both will attract attention, calling even casual observers to look at them as they descend toward the west-northwest sky, finally setting at around 10:30 p.m. local time. As was the case with Regulus, binoculars will enhance the view of Venus with the moon. You'll no doubt notice Earthshine – sunlight reflected from off of the Earth toward the moon, which will faintly illuminate its dark part with a greyish-blue glow, seemingly imparting a three-dimensional effect.
Venus for the balance of the year
Near the start of this year, Venus was situated behind the sun at superior conjunction (on Jan. 9) and entered the evening sky, yet it was hidden from our view for many weeks due to its close proximity to the sun. But Venus rapidly climbed out of the bright evening twilight during March, becoming by far the most brilliant of all the "stars," and by mid-June it stood nearly 30 degrees above the sunset horizon and was setting 2.5 hours after the sun.
Since then, Venus has taken a track placing it increasingly to the south of the sun's path across the sky. The result of this is that although its angular distance from the sun continues to increase, this is balanced out by its southerly track, which in the coming days and weeks will actually cause it to become progressivelylower in the sky and set gradually earlier relative to the sun.
As such, compared to now, Venus will actually be noticeably lower in the western evening sky at its greatest elongation (46 degrees) on Aug. 17. Come the start of October, it rapidly sinks, appearing as an increasingly large, thinning crescent through telescopes and steadily-held binoculars. While less of its surface will be illuminated, Venus's angular size will increase as the planet approaches Earth in its orbit.
At mid-northern latitudes, skywatchers will have to struggle to catch Venus very low in the west-northwest soon after sunset during the opening nights of October. It falls past the sun on Oct. 26 – well south of it (6 degrees) at this inferior conjunction, so any chance of trying to get a glimpse of it on those evenings and mornings of adjacent days will be solely for those who reside south of the equator, in the Southern Hemisphere.
But during November, Venus will dramatically sprout up into the morning sky, ultimately grabbing the attention of early risers and providing us with a perfect "Star in the East" adorning the predawn sky during the Christmas season.
Editor's note: If you capture an amazing image of Venus with Regulus or the moon and would like to share it with Space.com for a story or gallery, send images and comments in to: [email protected].
Joe Rao serves an Associate at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmers' Almanac and other publications, and he is also an on-camera meteorologist for Verizon FiOS1 News, Lower Hudson Valley, NY. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com. | 0.877879 | 3.452612 |
An asteroid or meteor is more likely to hit Earth because Earth is a lot bigger than the Moon, giving a meteoroid more area to hit! But we can see many thousands of craters on the Moon and we only know of about 180 on Earth! Why is that?
The truth is both the Earth and the Moon have been hit many, many times throughout their long 4.5 billion year history.
Where did all of Earth's craters go?
The main difference between the two is that Earth has processes that can erase almost all evidence of past impacts. The Moon does not. Pretty much any tiny dent made on the Moon’s surface is going to stay there.
Three processes help Earth keep its surface crater free. The first is called erosion. Earth has weather, water, and plants. These act together to break apart and wear down the ground. Eventually erosion can break a crater down to virtually nothing.
The Moon has almost no erosion because it has no atmosphere. That means it has no wind, it has no weather, and it certainly has no plants. Almost nothing can remove marks on its surface once they are made. The dusty footsteps of astronauts who once walked on the Moon are still there today, and they aren’t going anywhere anytime soon.
The second thing is something called tectonics. Tectonics are processes that cause our planet’s surface to form new rocks, get rid of old rocks, and shift around over millions of years.
Because of tectonics, the surface of Earth is recycled many times throughout its long history. As a result, very few rocks on Earth are as old as the rocks on the Moon. The Moon has not had tectonics for billions of years. That’s a lot more time for craters to form and stay put.
The third thing is volcanism. Volcanic flows can cover up impact craters. This is a major way impact craters get covered up elsewhere in our solar system, but it is less important than the recycling of crust here on Earth. The Moon once had large volcanic flows way in the past that did cover up many of the bigger earlier impacts, but it has been without volcanism for around three billion years.
A powerless Moon
The Moon may attract fewer bits of space rock than the Earth, but the Moon is powerless to do anything about it after it has been hit. Once something hits the Moon, that event becomes frozen in time. Earth, on the other hand, simply brushes these impact craters off and moves on with its life.
No wonder there are so many craters on the Moon compared to Earth! | 0.849997 | 3.451491 |
the clocks paradox, also called the twins paradox. an error in the theory of relativity.
here’s a clear video presentation of the paradox, one minute long, without useless additional information or inserted secondary elements to mess with your understanding..
there are some “solutions” to the paradox, by physics professors, using complex mathematics, showing solution with the difference in speed only, without the use of acceleration/deceleration. the academics are claiming that those physicists who explain the paradox with gravitational effect, don’t know what they are talking about. the problem with the complex math is that the professors fail to produce the calculations twice, beginning once from the reference point of one observer, and then from the reference point of another observer. that can only mean one thing — the math is wrong. there must be an error in the formulas. to prove the clocks/twins paradox with speed only, without local gravity produced by acceleration and deceleration, the math must be performed twice, once from each reference point, coming to a different result with the same formulas, which is impossible. there are careers involved, and tenures, thus it makes total sense for the professors to stop short before performing the same calculations again, from another point of reference in the clocks/twins paradox.
also there are some “solutions” described with the help of graphs (in the end of the article i give one example), but the same issue remains — there are clear logical errors. it is easy for anyone to debunk a “solution” without going into details of an explanatory presentation — simply let the demonstration to be performed twice, coming from each reference point. one must be able to, using exactly the same demo from the beginning till the end, without arbitrary changes to formulas or graphs, come to a different result from different reference point. they must show that in first demonstration the clock of one observer, who is the reference, is ticking faster, and on repeated calculation the clock of another observer, who is taken as reference, is ticking slower. it is impossible.
this is one of the contradictions in logic over which i was fighting with my physics teachers in my school times. i didn’t have a name to the paradox then, i just noticed the error. back then, for me the paradox of clocks was resolved by the existence of aether. in fact the whole trouble began when a physics teacher said that the aether doesn’t exist. then i came in with my logic that it will create problems in the theory of relativity. later i realized that even the existence of aether doesn’t resolve the paradox, because a “stationary” observer on earth may in fact be moving with enormous speed through the aether together with the earth or solar system or galaxy or cluster of galaxies, who knows. the speeding space ship will move in one direction through the aether, and then on another direction coming back to earth, in the result having the same amount of aether passed through the space ship as through the stationary observer on earth during the same time period.
thus the existence of the aether is not a solution to the relativity problem in clocks/twins paradox. it could only be a solution if earth would be stationary relative to aether. more probable is that our galaxy is closer to a stationary position in aether, which means that in different points of rotation around the galaxy and around the sun, the earth is moving at different speeds through the aether. this could be possible to measure and to find out the stationary reference point of the aether in the universe.
to those who missed my article on existence of aether read here..
the only way to resolve the paradox is to revisit the theory of relativity critically. in my view the solution is in the effect of gravity, instead of the effect of speed. refer to my articles about it..
the fact that technological advances in the precision of measurements and modern supercomputers have proven the theory of relativity to be correct many times, is not an obstacle to further scrutiny of the theory. some of the formulas may have errors in them. to put it into computer slang: “garbage in — garbage out”. this is in no way to diminish the value of current understanding in physics, i am simply saying that we are far from knowing everything and from being always correct. physics textbooks have been rewritten hundreds of times. nevertheless, the physics books have way more truth in them than holy scriptures.
to conclude the article, in the video below is an example of a popular, but wrong solution to the paradox. the connecting lines on the graph are there suddenly changing direction. if the reference point was the same, then the lines should have gone all in one direction on the entire length of the graph, or they show going back in time. the lines could only change direction, if in the middle of the graph the reference point was suddenly changed, arbitrarily, without finishing the explanation from the first reference point. and on top of that, the graph was fit into an assumption of slowing of time of a moving object from the very beginning. a correct presentation of a solution must give the correct answer in the end, with no arbitrary manipulation of data or presumption of facts.
watch the video..
i have seen many such graphs, supposedly explaining different phenomena in physics, presented in a visually appealing form and told with a nice clear voice suggesting to listeners knowledge of the subject, but in fact are arbitrary drawings of graphs and pointless calculations fitting some presumed truths, a show-off for those who don’t know any better.
my advice is, don’t take any explanations without critical thinking, either from textbooks, popular ones on social media, or rare and new ones.. neither mine. i may also make mistakes. in any case i do my best to avoid any errors, thinking deeply before publishing my solutions. when i doubt in my understanding of a subject, then i state it next to the presented ideas, not to sound like i know the ultimate truth, misleading others and wasting their time. | 0.808328 | 3.492849 |
A year ago a team of radio astronomers startled the world with the first photograph of a black hole, lurking like the eye of Sauron in the heart of a distant galaxy. Now it appears there was more hiding in that image than we had imagined.
When you point a telescope at a black hole, it turns out you don’t just see the swirling sizzling doughnut of doom formed by matter falling in. You can also see the whole universe. Light from an infinite array of distant stars and galaxies can wrap around the black hole like ribbons around a maypole, again and again before coming back to your eye, or your telescope.
“The image of a black hole actually contains a nested series of rings,” said Michael Johnson of the Harvard-Smithsonian Center for Astrophysics, not unlike the rings that form around your bathtub drain.
Dr. Johnson was lead author of a study, describing the proposed method that would allow our telescopes to pry more secrets from the maw of any black hole, that was published in the March 18 edition of the journal Science Advances.
He and other authors of the paper are also members of the team operating the Event Horizon Telescope, a globe-girding network of radio telescopes that made that first image of a black hole. Their telescope saw these rings, but it didn’t have enough resolution to distinguish them, so they were blurred into a single feature.
The work, scientists with the project said, pointed toward new ways to shed light, so to speak, on the properties of black holes, particularly by adding a radio telescope in space to the existing E.H.T. network.
“This paper is, in my professional capacity, very cool!” Shep Doeleman, also of Harvard-Smithsonian and leader of the E.H.T. collaboration, said in an email.
Andrew Strominger, a Harvard theorist and co-author of the paper, said, “Understanding the intricate details of this historic experimental observation has forced theorists like myself to think about black holes in a new way.”
Black holes are potholes in eternity, so massive that they swallow even light. They were an unwelcome prediction of Albert Einstein’s theory of gravity, general relativity. It describes gravity as the warping of space-time by mass and energy. Too much in one place would cause space-time to sag without limit.
Einstein thought that was crazy, but astronomers have found that space is littered with these apocalyptic creatures. There seems to be a supermassive black hole, weighing millions or billions of times more than the Sun, lurking in the center of every galaxy.
The Event Horizon Telescope, named after the edge, the point of no return from a black hole, consisted of eight radio observatories on six mountains and four continents. All that observing power was yoked together by a technique called very-long baseline interferometry, to achieve the resolution of a telescope as big as the Earth. For 10 days in April 2017 they pointed it at the center of the giant galaxy M87 in the Virgo constellation, where there is a black hole as massive as six billion Suns belching tongues of radio fire.
The resultant image of gases heated to billions of degrees swirling around the cosmic drain matched the predictions of Einstein’s theory, as far as anyone can tell. A copy of the telescope’s vision now resides in the permanent photography collection of the Museum of Modern Art in New York.
How They Took the First Picture of a Black Hole
A planet-sized network of radio telescopes has assembled the first image of a black hole.
But the Event Horizon’s work has barely begun, Dr. Doeleman said. For one thing the scientists are trying to make a movie of the supermassive black hole in the center of our own Milky Way galaxy; a summertime attempt was recently called off because of the coronavirus pandemic.
If they could increase the size of their event horizon network by adding an antenna in space, Dr. Doeleman said, they could gain enough resolution to see individual photon rings, as they are called, turning the event horizon into “a true cosmic laboratory for testing our most fundamental theories.”
As Peter Galison of Harvard, another E.H.T. collaborator said, “As we peer into these rings, we are looking at light from all over the visible universe, we are seeing farther and farther into the past, a movie, so to speak, of the history of the visible universe.”
Dr. Johnson said there were several space radio telescopes on the drawing boards that could fit the bill. One is a Russian mission called Millimetron, which is optimistically hoping to launch in 2029. Another is the Origins Space Telescope, which has been proposed to NASA for a launch in 2035.
Dr. Johnson said astronomers don’t know the mass of the M7 black hole they revealed last year to better than 10 percent accuracy, nor do they know if and how fast it is spinning. A space mission with a radio antenna would allow them to see the ring structure and determine the M87’s mass to an accuracy of a fraction of a percent, and could estimate its spin.
All this if Einstein was right, he added. Other theories of gravity and other types of compact objects (wormholes, naked singularities, boson stars) would suggest a very different ring structure.
“So this is a way of studying exactly what lies at the centers of galaxies, in a way that we can never learn from larger scale measurements such as the orbits of stars or gas,” Dr. Johnson said.
Sync your calendar with the solar system
Never miss an eclipse, a meteor shower, a rocket launch or any other astronomical and space event that’s out of this world. | 0.898317 | 3.844339 |
European scientists are meeting this week to consider their best option for exploring Europa, the moon of Jupiter.
They have a number of ideas that could fit as add-ons to US missions that are likely to be launched in the 2020s.
The concepts range from remote-sensing instruments to penetrators that would try to burrow beneath Europa's ice-encrusted surface.
Whatever option is chosen, it will first have to win the support of the European Space Agency.
The Paris-based organisation is about to issue a call for proposals to fill a medium-cost launch opportunity - and the invitation will cover the full gamut of space exploration, not just planetary science.
Nonetheless, there is an offer on the table to Esa from its American counterpart, Nasa, to participate in the Europa ventures.
These missions will likely include a probe, to be launched in 2022, that will make repeated passes of the moon.
It is very probable also that Nasa will send another craft to make a soft landing. This could launch in 2022 with the first mission, or separately a couple of years later.
Europa - Icy moon of Jupiter
Discovered by the famous Italian astronomer Galileo Galilei in 1610
Orbits 670,900km from Jupiter; same hemisphere always faces the gas giant
Nasa's Galileo probe returned pictures of its cracked surface in the 1990s
It likely has a small metal core surrounded by silicate rock
Its global ocean of liquid water is covered by a thick layer of ice
Considered a promising place to look for microbial life beyond Earth
The European Europa community believes the opportunity to join in is simply too good to pass up.
Europa is one of the most exciting destinations in the Solar System.
Its icy surface hides a deep liquid ocean that could provide a suitable habitat for microbial organisms to flourish.
The researchers meeting at the Observatoire de Paris on Tuesday have been woking on broadly five concepts. These are:
a remote-sensing instrument that would go on the Americans' 2022 probe
a small free-flying satellite that would detach from this probe
a small satellite that would detach from the lander's "mothership"
one or two instrumented projectiles that would drop from the mothership
an instrument to ride on the soft lander and do science at the surface
Of all of these concepts, the one that has been most intensively studied is the penetrator.
This "hard lander" technology is British-led, and has attracted Esa development money in the past.
Demonstrations of the capability have been run by Airbus, the big pan-European aerospace company.
In 2013, it fired a prototype into a block of ice to find out how the technology might perform at Europa.
The steel "missile" struck its target at 300m/s, before coming to a rapid stop.
"For a few milliseconds, it's quite a shock for the instruments," said Geraint Jones from the Mullard Space Science Laboratory, University College London.
"300m/s is around 700mph. Yes, it's very fast, but some of the instruments have been tested at these speeds and they survived. They worked to take data after the impact and store it safely," he told BBC News.
Instruments you might put on penetrator include a seismometer to study the interior of Europa, or a miniature laboratory to check for signs of interesting chemistry.
As well being presented again at the Paris gathering, the penetrator technology is also being showcased here in Vienna at the European Geosciences Union General Assembly.
The Europa community has asked an independent panel to asses the various mission ideas and then advise it on what should be proposed in response to the forthcoming Esa call, which is likely to come at the end of April.
Getting the backing of Esa will be one thing; aligning that support with the funding and programmatic cycles of Nasa will be quite another, however. The European Europa scientists know this but are undeterred.
"One thing is true: we are very enthusiastic about proposing something, and proposing for that mission which will land on Europa for the first time in the space age. It's going to be a big event, and I am sure it is going to be a big priority for the world community," said Michel Blanc, from the Research Institute in Astrophysics and Planetology in Toulouse.
The European Space Agency is already planning to visit Europa briefly on its own with a probe called Juice. This mission's main target is actually another of Jupiter's moons, Ganymede, and so Juice will make just two flybys of Europa.
The mission is scheduled to launch in 2022, arriving at the Jovian system in 2030.
Depending on which rocket the Americans decide to use, they could be at Europa before Juice. | 0.822791 | 3.338356 |
Black holes are the only objects in the Universe that can trap light by sheer gravitational force. Scientists believe they are formed when the corpse of a massive star collapses in on itself, becoming so dense that it warps the fabric of space and time.
And any matter that crosses their event horizons, also known as the point of no return, spirals helplessly toward an unknown fate. Despite decades of research, these monstrous cosmological phenomena remain shrouded in mystery.
They're still blowing the minds of scientists who study them. Here are 10 reasons why:
Black holes do not suck.
Some think that black holes are like cosmic vacuums that suck in the space around them when, in fact, black holes are like any other object in space, albeit with a very strong gravitational field.
If you replaced the Sun with a black hole of equal mass, Earth would not get sucked in – it would continue orbiting the black hole as it orbits the Sun, today.
Black holes look like they're sucking in matter from all around, but that's a common misconception. Companion stars shed some of their mass in the form of stellar wind, and the material in that wind then falls into the grip of its hungry neighbour, a black hole.
Einstein didn't discover black holes.
Einstein didn't discover the existence of black holes – though his theory of relativity does predict their formation. Instead, Karl Schwarzschild was the first to use Einstein's revolutionary equations and show that black holes could indeed form.
He accomplished this the same year that Einstein released his theory of general relativity in 1915. From Schwarzschild's work came a term called the Schwarzschild radius, a measurement of how small you'd have to compress any object to create a black hole.
Long before this, British polymath John Michell predicted the existence of 'dark stars' so massive or so compressed that they could possess gravitational pulls so strong not even light could escape; black holes didn't get their universal name until 1967.
Black holes will spaghettify you and everything else.
Black holes have this incredible ability to literally stretch you into a long spaghetti-like strand. Appropriately, this phenomenon is called 'spaghettification'. Look it up.
The way it works has to do with how gravity behaves over distance. Right now, your feet are closer to the centre of Earth and are therefore more strongly attracted than your head. Under extreme gravity, say, near a black hole, that difference in attraction will actually start working against you.
As your feet begin to get stretched by gravity's pull, they will become increasingly more attracted as they inch closer to the centre of the black hole. The closer they get, the faster they move. But the top half of your body is farther away and so is not moving toward the centre as fast. The result: spaghettification!
Black holes could spawn new universes.
It might sound crazy that black holes could spawn new universes – especially since we're not sure other universes exist – but the theory behind this is an active field of research today.
A very simplified version of how this works is that our Universe today, when you look at the numbers, has some extremely convenient conditions that came together to create life. If you tweaked these conditions by even a miniscule amount, then we wouldn't be here.
The singularity at the centre of black holes breaks down our standard laws of physics and could, in theory, change these conditions and spawn a new, slightly altered universe.
Black holes literally pull the space around them.
Picture space as a stretched rubber sheet with criss-crossing grid lines. When you place an object on the sheet, it sinks a little.
The more massive an object you put on the sheet the deeper it sinks. This sinking effect distorts the grid lines so they are no longer straight, but curved.
The deeper the well you make in space, the more space distorts and curves. And the deepest of wells are made by black holes. Black holes create such a deep well in space that nothing has enough energy to climb back out, not even light.
Black holes are the ultimate energy factories.
Black holes can generate energy more efficiently than our Sun.
The way this works has to do with the disk of material that orbits around a black hole. The material that is nearest to the fringe of the event horizon on the inner edge of the disk will orbit much more quickly than material at the very outer edge of the disk. This is because the gravitational pull is stronger near the event horizon.
Because the material is orbiting and moving so rapidly, it heats up to billions of degrees Fahrenheit, which has the ability to transform mass from the material into energy in a form called blackbody radiation.
To compare, nuclear fusion converts about 0.7 percent of mass into energy. The condition around a black hole converts 10 percent of mass into energy. That's a big difference!
Scientists have even proposed that this kind of energy could be used to power black hole starships of the future.
There is a supermassive black hole at the centre of our galaxy.
Scientists believe there is be a supermassive black hole at the centre of nearly every galaxy – including our own. These black holes actually anchor galaxies, holding them together in the space.
The black hole at the centre of the Milky Way, Sagittarius A, is more than four million times more massive then our sun. Although the black hole, which is almost 30,000 light years away, is pretty dormant at the moment, scientists believe that 2 million years ago it erupted in an explosion that may have even been visible from Earth.
Black holes slow down time.
To understand why, think back on the twin experiment that is often used to explain how time and space work together in Einstein's theory of general relativity:
One twin stays on Earth while the other one zooms out into space at the speed of light, turns around, and returns home. The twin that travelled through space is significantly younger because the faster you move, the slower time passes for you.
As you reach the event horizon, you are moving at such high speeds due to the strong gravitational force from the black hole, that time will slow down.
Black holes evaporate over time.
This surprising discovery was first predicted by Stephen Hawking in 1974. The phenomenon is called Hawking radiation, after the famous physicist.
Hawking radiation disperses a black hole's mass into space and over time, and will actually do this until there is nothing left, essentially killing the black hole. This is why Hawking radiation is also known as black hole evaporation.
Anything can become a black hole, in theory.
The only difference between a black hole and our Sun is that the centre of a black hole is made of extremely dense material, which gives the black hole a strong gravitational field. It's that gravitational field that can trap everything, including light, which is why we can't see black holes.
You could theoretically turn anything into a black hole.
If you shrunk our Sun down to a size of only 3.7 miles (6 km) across, for example, then you would have compressed all of the mass in our sun down to an incredibly small space, making it extremely dense and also making a black hole. You could apply the same theory to Earth or to your own body.
But in reality, we only know of one way that can produce a black hole: the gravitational collapse of an extremely massive star that's 20 to 30 times more massive than our Sun.
Randy Astaiza contributed to an earlier version of this post.
This article was originally published by Business Insider.
More from Business Insider: | 0.816775 | 4.043468 |
Using the MUSE instrument aboard ESO’s Very Large Telescope (VLT), astronomers have made a three dimensional view of the famous Pillars of Creation – a photograph taken by Hubble 20 years ago showing elephant trunks of interstellar gas and dust in the Eagle Nebula, some 7,000 light years from Earth. The 3D image shows never before seen details of the dust columns, greatly expanding scientists’ knowledge of how these formed, but also what’s in stored for them in the future.
These beautiful features were born out of the intense energy spewed by new stars in the Eagle Nebula. It’s actually a classic example column-like shapes that develop in the giant clouds of gas and dust nearby newborn stars.
The same stars that formed the pillars will also destroy them, however. On one side, the ultraviolet radiation and stellar winds gushing from freshly formed blue-white O and B stars blow away less dense materials from their vicinity, causing the pillars to form in the place. On the other side, however, the same radiation is breaking up the gas and dust columns. Denser pockets act like a shield and protect less dense regions from destruction, but not forever. Using this new data, astronomers operating the Very Large Telescope estimate the pillars lose roughly 70 times the mass of the sun every million years. This would entail that the Pillars of Creation only have three million years left before they’re obliterated. It’ll be only the Pillars of Destruction that remain in the aftermath.
The new study also reports fresh evidence for two gestating stars in the left and middle pillars as well as a jet from a young star that had escaped attention up to now, as reported in Monthly Notices of the Royal Astronomical Society. | 0.898608 | 3.347344 |
A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. By extension, this can be applied to any planet: for example, "Martian year".
A seasonal year is the time between successive recurrences of a seasonal event such as the flooding of a river, the migration of a species of bird, the flowering of a species of plant, the first frost, or the hottest day of the year. All of these events can have wide variations of more than a month from year to year
Solar calendars usually aim to predict the seasons, but because the length of individual seasonal years varies significantly, they instead use an astronomical year as a surrogate. For example, the ancient Egyptians used the heliacal rising of Sirius to predict the flooding of the Nile.
A Julian year is exactly 365.25 days, the average length of the year in the Julian calendar. It is still used in astronomical calculations because of the very simple conversion between Julian dates and Julian years: 100 Julian years is just another way of saying 36525 days.
The sidereal year is the time for the Earth to complete one revolution of its orbit, as measured in a fixed frame of reference (such as the fixed stars, Latin sidus). Its duration in SI days of 86,400 SI seconds each is on average:
A tropical year is the time for the Earth to complete one revolution with respect to the framework provided by the intersection of the ecliptic (the plane of the orbit of the Earth) and the plane of the equator (the plane perpendicular to the rotation axis of the Earth). Because of the precession of the equinoxes , this framework moves slowly westward along the ecliptic with respect to the fixed stars (with a period of about 26,000 tropical years); as a consequence, the Earth completes this year before it completes a full orbit as measured in a fixed reference frame. Therefore a tropical year is shorter than the sidereal year. The exact length of a tropical year depends on the chosen starting point: for example the vernal equinox year is the time between successive vernal equinoxes. The mean tropical year (averaged over all ecliptic points) is:
- 365.24218967 days (365d 5h 48m 45s) (at the epoch J2000.0).
The anomalistic year is the time for the Earth to complete one revolution with respect to its apsides. The orbit of the Earth is elliptical; the extreme points, called apsides, are the perihelion, where the Earth is closest to the Sun (January 2 in 2000), and the aphelion, where the Earth is farthest from the Sun (July 2 in 2000). Because of gravitational disturbances by the other planets, the shape and orientation of the orbit are not fixed, and the apsides slowly move with respect to a fixed frame of reference. Therefore the anomalistic year is slightly longer than the sidereal year. It is also longer than the tropical year (the basis of Gregorian calendar) and so the date of the perihelion gradually advances every year. It takes 21,000 tropical years for the ellipse to revolve once relative to the fixed stars, or for either apside to advance once through all dates of the Julian or Gregorian year. The average duration of the anomalistic year is:
- 365.259635864 days (365d 6h 13m 52s) (at the epoch J2000.0).
The eclipse year or ecliptic year is the time for the Sun (as seen from the Earth) to complete one revolution with respect to the same lunar node (a point where the Moon's orbit intersects the ecliptic). This period is associated with eclipses: these occur only when both the Sun and the Moon are near these nodes; so eclipses occur within about a month of every half eclipse year. Hence there are two eclipse seasons every eclipse year. The average duration of the eclipse year is:
- 346.620075883 days (346d 14h 52m 54s) (at the epoch J2000.0).
The full moon cycle or fumocy is the time for the Sun (as seen from the Earth) to complete one revolution with respect to the perigee of the Moon's orbit. This period is associated with the apparent size of the full moon, and also with the varying duration of the synodic month. The duration of one full moon cycle is:
- 411.78443029 days (411d 18h 49m 34s) (at the epoch J2000.0).
A heliacal year is the interval between the heliacal risings of a star. It equals the sidereal year only if the star is on the ecliptic. It differs from the sidereal year for stars north or south of the ecliptic because of the significant angle (23.5°) between Earth's celestial equator and the ecliptic.
The Sothic year is the interval between heliacal risings of the star Sirius. Its duration is very close to the mean Julian year of 365.25 days.
The Gaussian year is the sidereal year for a planet of negligible mass (relative to the Sun) and unperturbed by other planets that is governed by the Gaussian gravitational constant. Such a planet would be slightly closer to the Sun than Earth's mean distance. Its length is:
- 365.2568983 days (365d 6h 9m 56s).
The Besselian year is a tropical year that starts when the fictitious mean Sun reaches an ecliptic longitude of 280°. This is currently on or close to 1 January. It is named after the 19th century German astronomer and mathematician Friedrich Bessel. An approximate formula to compute the current time in Besselian years from the Julian day is:
- B = 2000 + (JD - 2451544.53)/365.242189
Variation in the length of the year and the day
The exact length of an astronomical year changes over time. The main sources of this change are:
- The precession of the equinoxes changes the position of astronomical events with respect to the apsides of Earth's orbit. An event moving toward perihelion recurs with a decreasing period from year to year; an event moving toward aphelion recurs with an increasing period from year to year.
- The gravitational influence of the Moon and planets changes the shape of the Earth's orbit.
Summary of various kinds of year
- 353, 354 or 355 days — the lengths of regular years in some lunisolar calendars
- 354.37 days — 12 lunar months; the average length of a year in lunar calendars
- 365 days — a common year in many solar calendars; ~31.53 million seconds
- 365.24219 days — a mean tropical year near the year 2000
- 365.2424 days — a vernal equinox year.
- 365.2425 days — the average length of a year in the Gregorian calendar
- 365.25 days — the average length of a year in the Julian calendar; the light year is based on it; it is 31,557,600 seconds
- 365.2564 days — a sidereal year
- 366 days — a leap year in many solar calendars; 31.62 million seconds
- 383, 384 or 385 days — the lengths of leap years in some lunisolar calendars
- 383.9 days — 13 lunar months; a leap year in some lunisolar calendars
A common year is 365 days = 8,760 hours = 525,600 minutes = 31,536,000 seconds.
A leap year is 366 days = 8,784 hours = 527,040 minutes = 31,622,400 seconds.
The 400-year cycle of the Gregorian calendar has 146097 days and hence exactly 20871 weeks. | 0.865371 | 3.887116 |
Astronomers on Wednesday unveiled the first photo of a black hole, one of the star-devouring monsters scattered throughout the Universe and obscured by impenetrable shields of gravity. The image of a dark core encircled by a flame-orange halo of white-hot plasma looks like any number of artists’ renderings over the last 30 years.But this time, it’s the real deal.“The history of science will be divided into the time before the image, and the time after the image,” said Michael Kramer, director at the Max Planck Institute for Radio Astronomy. Carlos Moedas, European Commissioner for Research, Science and Innovation called the feat a “huge breakthrough for humanity.”The supermassive black hole immortalised by a far-flung network of radio telescopes is 50 million lightyears away at the centre of a galaxy known as M87. “It’s a distance that we could have barely imagined,” Frederic Gueth, an astronomer at France’s National Centre for Scientific Research (CNRS) and co-author of studies detailing the findings, told AFP.Most speculation had centred on the other candidate targeted by the Event Horizon Telescope: Sagittarius A*, a closer but smaller black hole at the centre of our own galaxy, the Milky Way.Locking down an image of M87’s supermassive black hole at such distance is comparable to photographing a pebble on the Moon, the scientists said.It was also very much a team effort.“Instead of constructing a giant telescope that would collapse under its own weight, we combined many observatories,” Michael Bremer, an astronomer at the Institute for Millimetric Radio Astronomy (IRAM) in Grenoble, told AFP.Earth in a thimbleOver several days in April 2017, eight radio telescopes in Hawaii, Arizona, Spain, Mexico, Chile, and the South Pole zeroed in on Sag A* and M87.Knitted together, they formed a virtual observatory some 12,000 kilometres across — roughly the diameter of Earth.“The data is like an incomplete puzzle set,” said team member Monika Moscibrodzka, an astronomer at Radboud University. “We only see pieces of the real true image, and then we have to fill in the gaps of the missing pieces.”In the end, M87 was more photogenic. Like a fidgety child, Sag A* was too “active” to capture a clear picture, the scientists said.“What we see in the image is the shadow of the black hole’s rim — known as the event horizon, or the point of no return — set against the luminous accretion disk,” Gueth told AFP.The unprecedented image — so often imagined in science and science fiction — has been analysed in six studies co-authored by 200 experts from 60-odd institutions and published Wednesday in Astrophysical Journal Letters.“I never thought that I would see a real one in my lifetime,” said CNRS astrophysicist Jean-Pierre Luminet, author in 1979 of the first digital simulation of a black hole. Coined in the mid-60s by US physicist John Archibald Wheeler, the term “black hole” refers to a point in space where matter is so compressed as to create a gravity field from which even light cannot escape. | 0.841906 | 3.591121 |
| Press Releases
September 14, 2012
|NASA Mars Rover Opportunity Reveals Geological Mystery
|'Puzzling Little Martian Spheres That Don't Taste Like 'Blueberries'
Small spherical objects fill the field in this mosaic combining four images from the Microscopic Imager on NASA's Mars Exploration Rover Opportunity.
Image Credit: NASA/JPL-Caltech/Cornell Univ./ USGS/Modesto Junior College
Full Image and Caption
PASADENA, Calif. -- NASA's long-lived rover Opportunity has returned an image of the Martian surface that is puzzling researchers.
Spherical objects concentrated at an outcrop Opportunity reached last week differ in several ways from iron-rich spherules nicknamed "blueberries" the rover found at its landing site in early 2004 and at many other locations to date.
Opportunity is investigating an outcrop called Kirkwood in the Cape York segment of the western rim of Endeavour Crater. The spheres measure as much as one-eighth of an inch (3 millimeters) in diameter. The analysis is still preliminary, but it indicates that these spheres do not have the high iron content of Martian blueberries.
"This is one of the most extraordinary pictures from the whole mission," said Opportunity's principal investigator, Steve Squyres of Cornell University in Ithaca, N.Y. "Kirkwood is chock full of a dense accumulation of these small spherical objects. Of course, we immediately thought of the blueberries, but this is something different. We never have seen such a dense accumulation of spherules in a rock outcrop on Mars."
The Martian blueberries found elsewhere by Opportunity are concretions formed by action of mineral-laden water inside rocks, evidence of a wet environment on early Mars. Concretions result when minerals precipitate out of water to become hard masses inside sedimentary rocks. Many of the Kirkwood spheres are broken and eroded by the wind. Where wind has partially etched them away, a concentric structure is evident.
Opportunity used the microscopic imager its arm to look closely at Kirkwood. Researchers checked the spheres' composition by using an instrument called the Alpha Particle X-Ray Spectrometer on Opportunity's arm.
"They seem to be crunchy on the outside, and softer in the middle," Squyres said. "They are different in concentration. They are different in structure. They are different in composition. They are different in distribution. So, we have a wonderful geological puzzle in front of us. We have multiple working hypotheses, and we have no favorite hypothesis at this time. It's going to take a while to work this out, so the thing to do now is keep an open mind and let the rocks do the talking."
Just past Kirkwood lies another science target area for Opportunity. The location is an extensive pale-toned outcrop in an area of Cape York where observations from orbit have detected signs of clay minerals. That may be the rover's next study site after Kirkwood. Four years ago, Opportunity departed Victoria Crater, which it had investigated for two years, to reach different types of geological evidence at the rim of the much larger Endeavour Crater.
The rover's energy levels are favorable for the investigations. Spring equinox comes this month to Mars' southern hemisphere, so the amount of sunshine for solar power will continue increasing for months.
"The rover is in very good health considering its 8-1/2 years of hard work on the surface of Mars," said Mars Exploration Rover Project Manager John Callas of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Energy production levels are comparable to what they were a full Martian year ago, and we are looking forward to productive spring and summer seasons of exploration."
NASA launched the Mars rovers Spirit and Opportunity in the summer of 2003, and both completed their three-month prime missions in April 2004. They continued bonus, extended missions for years. Spirit finished communicating with Earth in March 2010. The rovers have made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life.
JPL manages the Mars Exploration Rover Project for NASA's Science Mission Directorate in Washington.
To view the image of the area, visit: http://www.nasa.gov/mission_pages/mer/multimedia/pia16139.html
For more information about Opportunity, visit: http://www.nasa.gov/rovers and http://marsrovers.jpl.nasa.gov .
You can follow the project on Twitter and on Facebook at: http://twitter.com/MarsRovers and http://facebook.com/mars.rover .
DC Agle 818-393-9011
Dwayne Brown 202-358-1726
Jet Propulsion Laboratory, Pasadena, Calif.
NASA Headquarters, Washington
NEWS RELEASE: 2012-290 | 0.825618 | 3.571263 |
Observational data collected over the years suggests the largest volcano on Jupiter’s moon Io—the most geologically active object in the Solar System—will erupt in mid-September, which is pretty much any moment now.
When it comes to eruptions, volcanoes tend to operate on their own unpredictable schedules. Such is not the case for Loki, however, the largest volcano on Io. When this thing blows, which it tends to do on the regular, it accounts for 15 percent of the moon’s total heat expenditure. So powerful is this 200-kilometer-wide (124-mile) volcano that astronomers can observe its tantrums using ground-based telescopes, making it the most thoroughly studied volcano not on Earth.
For the past 20 years, astronomer Julie Rathbun from the Planetary Science Institute in Arizona has watched in astonishment as this volcano erupts with eerie regularity. Her latest calculations suggest Loki will erupt in mid-September, as she told an audience today at the EPSC-DPS Joint Meeting 2019 in Geneva, Switzerland, according to a press release put out by the Europlanet Society. Prior to this, Rathbun correctly predicted that Loki would erupt in May 2018.
Indeed, Rathbun knows this volcano rather well. In 2002 she identified Loki as a periodic volcano. By analyzing data collected from 1988 to 2000, she saw that the horseshoe-shaped giant erupted at roughly 540-day intervals. But then the moon, true to the trickster god for which it is named, went off schedule during the 2000s, erupting less frequently and with no discernible pattern. That changed starting in 2013, when Rathbun identified a new schedule in which Loki erupted at roughly 475-day intervals, with eruptions lasting for around 160 days.
Loki, which Rathbun suspects is a large overturning lava lake (and sadly not an overturning lava cake), is predictable owing to its tremendous girth.
“Because of its size, basic physics are likely to dominate when it erupts, so the small complications that affect smaller volcanoes are likely to not affect Loki as much,” Rathbun was quoted as saying in the Europlanet Society release.
In a short paper put together for the EPSC-DPS meeting, Rathbun said Loki “is a lava lake with a crust that solidifies as it cools,” and the “amount of time between eruptions is the amount of time necessary for the crust to become gravitationally unstable and is, therefore, related to the porosity of the lava.”
But because Loki has a prior history of changing its schedule on a dime, Rathbun warned that her latest prediction is not ironclad.
“Volcanoes are so difficult to predict because they are so complicated,” she said. “Many things influence volcanic eruptions, including the rate of magma supply, the composition of the magma—particularly the presence of bubbles in the magma, the type of rock the volcano sits in, the fracture state of the rock, and many other issues.”
So, a super neat prediction for a super cool moon. Hopefully we’ll have something to report on in the coming days. | 0.830061 | 3.719741 |
August 8, 2019 report
Astronomers investigate AGN jet in the Messier 87 galaxy
Astronomers have taken a closer look at the relatively nearby Messier 87 (or M87) galaxy to investigate the jet of its active galactic nucleus (AGN). The new research, described in a paper published July 31 on arXiv.org, delivers important insights into the parameters of the jet, which could improve the understanding of AGNs in general.
AGNs are accreting, super-massive black holes residing at the centers of some galaxies, emitting powerful, high-energy radiation as they accrete gas and dust. These nuclei can form jets, having mostly cylindrical, conical or parabolic shapes, which are observed even on megaparsec scales.
Located some 53.5 million light years away in the Virgo cluster, M87 is a supergiant elliptical galaxy. It hosts one of the most well-known and remarkable jetted AGNs discovered to date. The jet of M87 is easily detected on a variety of physical scales, which enabled astronomers to obtain many high-quality images of this feature. This makes it a unique source to study the physics of jets in accreting black holes.
Now, a trio of astronomers from the University of Amsterdam, the Netherlands, led by Matteo Lucchini, has conducted another study of M87, focused on investigating the properties of its AGN jet. They analyzed the available dataset, mainly from NASA's Chandra and Fermi spacecraft, in order to unveil the jet's key parameters.
"In this paper, we employ a multi-zone model designed as a parametrization of general relativistic magneto-hydrodynamics (GRMHD); for the first time, we reproduce the jet's observed shape and multi-wavelength spectral energy distribution (SED) simultaneously. We find strong constraints on key physical parameters of the jet, such as the location of particle acceleration and the kinetic power," the astronomers wrote in the paper.
The study found that the location of particle acceleration occurs very close to the black hole, far closer to the central engine than the acceleration distance. Notably, high-resolution very-long-baseline interferometry (VLBI) images of the jet show a "pinching" of the outflow around this distance. This, according to the researchers, suggests that the initial injection of particle acceleration in the jet may be influenced by this pinching region.
Moreover, the astronomers matched their model's jet dynamics and shape with those inferred from direct imaging of the outflow through VLBI. This allowed them to find that the main contribution to the core's limited gamma-ray flux is due to inverse Compton scattering of the host galaxy's starlight, rather than synchrotron self-Compton (SSC).
Furthermore, the research found that in the case of M87, the radiating leptons need to be accelerated to very high Lorentz factors in order to extend the synchrotron spectrum up to the Chandra energy range. The study also revealed that the particle distribution in the jet is consistent with being isothermal, even beyond the dissipation region.
Summing up the results, the astronomers emphasized the importance of their study, noting that it could be fundamental for future investigations of M87 an other jetted AGNs.
"Our results have important implications both for comparisons of GRMHD simulations with observations, and for unified models of AGN classes. (…) Our results are particularly important in light of the upcoming observations of M87 with the Event Horizon Telescope, which provide even more detailed imaging of the regions near the black hole," the authors of the paper concluded.
© 2019 Science X Network | 0.845728 | 3.952622 |
NASA revealed Monday 10 new rocky, Earth-sized planets that could potentially have liquid water and support life.
The Kepler mission team released a survey of 219 potential exoplanets – planets outside of our solar system – that had been detected by the space observatory launched in 2009 to scan the Milky Way galaxy.
Ten of the new discoveries were orbiting their suns at a distance similar to Earth’s orbit around the sun, the so-called habitable zone that could potentially have liquid water and sustain life.
Kepler has already discovered 4,034 potential exoplanets, 2,335 of which have been confirmed by other telescopes as actual planets.
The 10 new Earth-size planets bring the total to 50 that exist in habitable zones around the galaxy.
“This carefully-measured catalog is the foundation for directly answering one of astronomy’s most compelling questions — how many planets like our Earth are in the galaxy?” said Susan Thompson, a Kepler research scientist and lead author of the latest study.
The latest findings were released at the Fourth Kepler and K2 science conference being held this week at NASA’s Ames research center in California.
(Related: [VIDEO] Breathtaking footage of Jupiter as NASA’s Juno craft orbits)
The Kepler telescope detects the presence of planets by registering minuscule drops in a star’s brightness that occurs when a planet crosses in front of it, a movement known as a transit.
The findings were compiled from data gathered during the first four years of the mission, which scientists processed to determine the size and composition of the planets observed.
The scientists found that the newly discovered planets tended to fall into two distinct categories – smaller, rocky planets that are usually around 75 percent bigger than Earth, and much larger, gaseous planets similar in size to Neptune.
NASA said the latest catalog is the most complete and detailed survey of potential exoplanets yet compiled. The telescope has studied some 150,000 stars in the Cygnus constellation, a survey which NASA said is now complete.
“The Kepler data set is unique, as it is the only one containing a population of these near Earth-analogs – planets with roughly the same size and orbit as Earth,” said Mario Perez of NASA’s Astrophysics Division. “Understanding their frequency in the galaxy will help inform the design of future NASA missions to directly image another Earth.”
The mission ran into technical problems in 2013 when mechanisms used to turn the spacecraft failed, but the telescope has continued searching for potentially habitable planets as part of its K2 project.
As of next year, NASA will continue its scan of the galaxy using Kepler’s successor, the Transiting Exoplanet Survey Satellite, or TESS, which will spend two years observing the 200,000 brightest nearby stars for Earth-like worlds.
Scientists also hope the James Webb Space telescope, which will replace the Hubble telescope in 2018, will be able to detect the molecular make-up of atmospheres of exoplanets, including the possibility of finding signatures of potential life forms.
Photo credit: istock.com/Khlongwangchao | 0.899606 | 3.607729 |
10 Weather-Fueled Facts about Antarctica
Most of us have at least a vague notion of what makes the North and South Poles so brutally, bone-chillingly cold: They receive less sunlight than the rest of the planet, what sunlight they do receive arrives at an angle, and they’re usually buried under endless mounds of ice and snow. This holds especially true for the South Pole and its centerpiece, Antarctica. Fewer people know, however, what drives Antarctic weather, or what results from it. Here are ten weather-related facts about the most southern continent that will put your polar meteorology ahead of the curve.
1. Antarctica is Colder Than the Arctic
The Antarctic is in fact the coldest location on Earth. This owes partly to the enormous, and enormously thick, ice sheet that covers about 98% of the continent. But that’s not the only reason: Antarctica also has stronger winds than the Arctic (or any other location on the planet), is surrounded by water (which holds its temperature longer than land), and has the highest average elevation of any continent (4,892 meters, or 8,200 feet). All of these factors combine to keep Antarctica’s average coastal weather around -10°C (14°F) and its inland around -55°C (-67°F). Naturally, the coldest weather recorded on Earth occurred in Antarctica: -89.2°C (-128.6°F) on July 21st, 1983.
2. It Was Once Warm in Antarctica
Despite how frigid the Antarctic is now, it was once as warm as the sun-soaked beaches of California. Studies at Yale suggest that some 40-50 million years ago, during the Eocene epoch, high atmospheric levels of CO2 created greenhouse-like conditions on Earth. Antarctica’s weather at that time averaged 14°C (57°F), with a high of 17°C (63°F), conditions that would quickly reduce the current Antarctic’s titanic icebergs and mountainous glaciers to common ocean swell.
3. Even at Its Hottest, Antarctica Keeps Its Cool
Since the Eocene, Antarctic weather tends toward the colder side. Even the most boiling temperature recorded in Antarctica was, by most standards, similar to a pleasant autumn day in the Pacific Northwest: At Esperanza Base, an Argentine research station sometimes visited on Antarctic Peninsula voyages, the temperature once reached 17.5°C (63.5°F) on March 24th, 2015.
4. Antarctica is Technically a Desert – Earth’s Largest
Due to the fact that Antarctica receives so little rainfall – the interior averages about 50 ml per year (two inches), usually as snow – it is recognized as a desert. But when Antarctica does something, it does it big: Antarctica is by far the largest desert on Earth, capable of encompassing the Gobi, Arabian, even the sprawling Sahara within its 14.2 million square km (5.5 million square miles). Think of that the next time you watch Lawrence of Arabia.
5. Antarctica Is Almost Entirely Covered in Ice
As mentioned before, some of Antarctica’s cold weather comes from the giant ice sheet covering most of the continent. This large ice sheet is actually two smaller sheets: The West Antarctic Ice Sheet (WAIS) is the smaller portion, and the East Antarctic Ice Sheet (EAIS) is the larger – though for the clarity of this article, we’ll refer to them as one. In total, the Antarctic ice sheet is made up of about 26.5 million square km of ice (6,400,000 square miles) and holds around 61% of the Earth’s fresh water supply. If the ice sheet melted, sea levels would rise roughly 58 meters (190 feet), enough to submerge many of the world’s lowest-lying cities.
6. The Antarctic Ice Sheet Is Over 40 Million Years Old
The longstanding cold weather in Antarctica has kept its ice sheet intact for timespans beyond human comprehension. After the Antarctic’s boardwalk-like Eocene weather cooled with the dropping of global carbon dioxide levels, the continent began to glaciate. This icing was aided by a period during which Earth’s orbit led to colder summers, as well as other potential factors, though it was the plummeting CO2 that contributed most directly to the formation and retention of the ice sheet. We can certainly guess, without need of much scientific background, how cold the Antarctic weather was by seeing how sizable that ice sheet eventually became.
By NASA Goddard's Scientific Visualization Studio [Public domain], via Wikimedia Commons
7. Antarctica’s Ice Averages 2 Km Thick (Over a Mile)
A walk of this distance might be no big matter, but a dig… Much different story. Some of the highest elevations on Earth are found in the Antarctic, due partially to the fact that most of its exceedingly thick ice sheet has formed over terrain that was well above sea level already. The resulting ice formations, lofty and surreal, are naturally a chief attraction during Antarctica cruises. The ice sheet itself was not only directly caused by Antarctica’s long history of freezing weather, but eventually became partially responsible for it – and other factors, as we will learn.
8. Earth’s Largest Iceberg Comes from Antarctica
It should come as no surprise, then, that the continent with the coldest weather, and hence Earth’s largest supply of ice, also produced Earth’s largest-known iceberg. Iceberg B-15, which broke away from the Ross Ice Shelf in late March of 2000, had a surface area of roughly 295 km (183 miles), making it larger than Jamaica and nearly the size of Connecticut. At its largest, B-15 once measured 37 km wide (23 miles) and 295 km long (183 miles). But over the ensuing years, it broke up into smaller pieces, the largest of which drifted north and fragmented in late 2005.
Iceberg B-15 by NSF/Josh Landis, employee 1999-2001 [Public domain], via Wikimedia Commons
9. Antarctic Winds Can Move at Speeds of 320 kph (200 mph)
One of the contributors to Antarctica’s weather is its strong, cold wind. There is in fact a name for the type of wind for which Antarctica is known: katabatic wind, rooted in the Greek word katabasis, or “descending.” Also called “fall winds,” these gravity-driven gusts push high-density air downward from above high-altitude slopes. Most of this wind usually only reaches speeds of around 18 kph (11 mph), but over the Antarctic’s enormous ice sheets, large concentrations of cold air build up over time and shove downward with considerable force. When that wind is funneled through narrower areas along Antarctica’s coast, for example, it can blow at hurricane speeds.
10. Antarctic Ice Melting Has Caused a Gravity Shift
Global warming no doubt has more surprises in store for us, but one of them was recently revealed when scientists discovered that the melting of Antarctica’s ice is actually weakening gravitational pull in that region. Gravity on Earth’s surface, far from a constant, varies slightly by location and is largely dependent on geological factors: the rotation of the planet, the position of ocean trenches and mountain ranges, and the presence of large masses of ice. When that ice is reduced in a given location, so too is the power of gravity in that location. The decreasing ice in Antarctica is having exactly this effect, a rather unexpected chapter in a continuing story. | 0.822768 | 3.4756 |
A new study by Jacob Haqq-Misra of the Blue Marble Space Institute of Science and his co-authors shows how climatic swings narrow the so-called habitable zone of other solar systems—to the point where planets around some types of stars may be altogether unsuitable for complex life.
The climate swings, called limit cycles, occur in the outer regions of a star’s habitable zone (those orbits in which liquid water could be stable on a planetary surface). The limit cycles lead to long periods of global glaciation alternating with periods of relative warmth. Our own planet has experienced global glaciations as well, called Snowball Earth events, but on Earth the ice cover is thought to have been thin, with some areas of open water. Snowball Earth events caused by limit cycles are expected to be more severe, with ice covers measured in kilometers. And that would make the evolution of complex life rather unlikely.
The research team, which also included James Kasting of Pennsylvania State University, found a close link between carbon dioxide outgassing rates and the occurrence of limit cycles. Planets with rates as high as Earth’s is today may not experience limit cycles at all. But there is a distinct possibility that our planet is anomalous in its high outgassing rates and ability to sustain a stable warm climate. If that is so, then Super-Earths—planets with a few times the mass of Earth—might be more likely places to find life in the outer reaches of a habitable zone, as they should have more carbon dioxide in their atmosphere than smaller (Earth-size) planets.
Limit cycles may have caused some of the global glaciations Earth experienced early in its history, when it was located in the outer reaches of the Sun’s habitable zone (the zone has moved outward over time). However, we have no corroborating evidence that carbon dioxide outgassing was less on early Earth than it is today, and that evidence would be hard to come by.
What implications do these new findings have for the likelihood of finding complex life, even intelligent life, on exoplanets? The outlook is bleak for F stars, both because of limit cycles and the short lifetimes of these stars, which usually last only one or two billion years. That leaves planets around G, K, and M stars as reasonable abodes for life. However, recent research indicates that M stars lose massive amounts of water during their evolution. They’re also exposed to intense radiation, and planets around these stars may be tidally locked, meaning that the same side always faces the star. G stars like our sun become more luminous with time, which means that their habitable zone moves outward. This effect will make Earth uninhabitable for humans in about a billion years. That leaves K stars (orange dwarf stars) as perhaps the most likely places to find complex life, though some G stars might also host planets with a substantial biosphere (as evidenced by Earth). The good news: K stars are fairly common, making up about 12 percent of all main sequence stars (compared to G stars, which make up 7.5 percent). So while the expected number of “cosmic zoos” may just have dropped a bit due to severe climate change on other planets, there still should be plenty of habitable worlds out there. | 0.84464 | 4.044151 |
Stars can be big or small, hot or cool, young or old. In order to properly organize all of the stars out there, astronomers have developed an organizational system called the Hertzsprung-Russell Diagram. This diagram is a scatter chart of stars that shows their absolute magnitude (or luminosity) versus their various spectral types and temperatures. The Hertzsprung-Russell diagram was developed by astronomers Ejnar Hertzsprung and Henry Norris Russell back in 1910.
The first Hertzsprung-Russell diagram showed the spectral type of stars on the horizontal axis and then the absolute magnitude on the vertical axis. Another version of the diagram plots the effective surface temperature of the star on one axis and the luminosity of the star on the other.
By using this diagram, astronomers are able to trace out the life cycle of stars, from young hot protostars, through the main sequence phase and into the dying red giant phases. It also shows how temperature and color relate to the stars at various stages in their lives.
If you look at an image of a Hertzsprung-Russell diagram, you can see there’s a diagonal line from the upper left to the lower right. Almost all stars fall along this line, and it’s known as the main sequence. In general, as luminosity goes down, temperature goes down as well. But there’s a branch that goes off horizontally at the 100 solar luminosity mark. These are the red giant stars nearing the end of their lives. They can be bright and cool, because they’re so large. But this stage usually only lasts a few million years.
Astronomers can also use the Hertzsprung-Russell diagram to estimate how far away stellar clusters are from Earth. By mapping out all the stars in the cluster and grouping them together and comparing them to groups of stars with known distances.
We have written many articles for Universe Today about the star life cycle. Here’s an article about the cluster M13, and how astronomers use the Hertzsprung-Russell diagram to study it.
Here are some good resources on the Internet for Hertzsprung-Russell diagram. Here’s a very simple version of the diagram from the University of Oregon, and here’s more information.
Much like any living being, stars go through a natural cycle. This begins with birth, extends through a lifespan characterized by change and growth, and ends in death. Of course, we’re talking about stars here, and the way they’re born, live and die is completely different from any life form we are familiar with.
For one, the timescales are entirely different, lasting on the order of billions of years. Also, the changes they go through during their lifespan are entirely different too. And when they die, the consequences are, shall we say, much more visible? Let’s take a look at the life cycle of stars.
Stars start out as vast clouds of cold molecular gas. The gas cloud could be floating in a galaxy for millions of years, but then some event causes it to begin collapsing down under its own gravity. For example when galaxies collide, regions of cold gas are given the kick they need to start collapsing. It can also happen when the shockwave of a nearby supernova passes through a region.
As it collapses, the interstellar cloud breaks up into smaller and smaller pieces, and each one of these collapses inward on itself. Each of these pieces will become a star. As the cloud collapses, the gravitational energy causes it to heat up, and the conservation of momentum from all the individual particles causes it to spin.
As the stellar material pulls tighter and tighter together, it heats up pushing against further gravitational collapse. At this point, the object is known as a protostar. Surrounding the protostar is a circumstellar disk of additional material. Some of this continues to spiral inward, layering additional mass onto the star. The rest will remain in place and eventually form a planetary system.
Depending on the stars mass, the protostar phase of stellar evolution will be short compared to its overall life span. For those that have one Solar Mass (i.e the same mass as our Sun), it lasts about 1000,000 years.
T Tauri Star:
A T Tauri star begins when material stops falling onto the protostar, and it’s releasing a tremendous amount of energy. They are so-named because of the prototype star used to research this phase of solar evolution – T Tauri, a variable star located in the direction of the Hyades cluster, about 600 light years from Earth.
A T Tauri star may be bright, but this all comes its gravitational energy from the collapsing material. The central temperature of a T Tauri star isn’t enough to support fusion at its core. Even so, T Tauri stars can appear as bright as main sequence stars. The T Tauri phase lasts for about 100 million years, after which the star will enter the longest phase of its development – the Main Sequence phase.
Eventually, the core temperature of a star will reach the point that fusion its core can begin. This is the process that all stars go through as they convert protons of hydrogen, through several stages, into atoms of helium. This reaction is exothermic; it gives off more heat than it requires, and so the core of a main sequence star releases a tremendous amount of energy.
This energy starts out as gamma rays in the core of the star, but as it takes a long slow journey out of the star, it drops down in wavelength. All of this light pushes outward on the star, and counteracts the gravitational force pulling it inward. A star at this stage of life is held in balance – as long as its supplies of hydrogen fuel lasts.
And how long does it last? It depends on the mass of the star. The least massive stars, like red dwarfs with half the mass of the Sun, can sip away at their fuel for hundreds of billions and even trillions of years. Larger stars, like our Sun will typically sit in the main sequence phase for 10-15 billion years. The largest stars have the shortest lives, and can last a few billion, and even just a few million years.
Over the course of its life, a star is converting hydrogen into helium at its core. This helium builds up and the hydrogen fuel runs out. When a star exhausts its fuel of hydrogen at its core, its internal nuclear reactions stop. Without this light pressure, the star begins to contract inward through gravity.
This process heats up a shell of hydrogen around the core which then ignites in fusion and causes the star to brighten up again, by a factor of 1,000-10,000. This causes the outer layers of the star to expand outward, increasing the size of the star many times. Our own Sun is expected to bloat out to a sphere that reaches all the way out to the orbit of the Earth.
The temperature and pressure at the core of the star will eventually reach the point that helium can be fused into carbon. Once a star reaches this point, it contracts down and is no longer a red giant. Stars much more massive than our Sun can continue on in this process, moving up the table of elements creating heavier and heavier atoms.
A star with the mass of our Sun doesn’t have the gravitational pressure to fuse carbon, so once it runs out of helium at its core, it’s effectively dead. The star will eject its outer layers into space, and then contract down, eventually becoming a white dwarf. This stellar remnant might start out hot, but it has no fusion reactions taking place inside it any more. It will cool down over hundreds of billions of years, eventually becoming the background temperature of the Universe. | 0.880003 | 3.740855 |
IN JANUARY NASA, America's space agency, released a massive, high-resolution image of Earth from space, a 64-megapixel update to the iconic "blue marble" shot snapped by Apollo 17 astronauts on their way to the moon in 1972. Gone was the monochromatic ocean of the Apollo era. It now glistens with a range of blues, from aquamarine to dark navy. Yet Earth was not always so beautiful. In its infancy, 4.5 billion years ago, the planet was a volcanic wasteland. It did not even have a moon.
Since then, Earth has grown in fits and starts. Its oceans, products of giant, moisture-spewing volcanoes, formed quickly, but its continents took hundreds of millions of years to surface—and billions more to acquire a thin layer of green. For eons, the planet veered wildly between extremes, impersonating a range of celestial bodies. The first oxygen-producing microbes rusted Earth to a Martian shade of red; later on, it froze, turning white like the moon.
In his new book, "The Story of Earth", Robert Hazen, a geophysicist at the Carnegie Institution in Washington and a professor of earth science at the nearby George Mason University, offers what is often literally a potted history of Earth's slow transition from blackened, lava-veined orb to vibrant biosphere. Dr Hazen is particularly interested in how life transformed the planet in its early years and in the mystery of abiogenesis: the spontaneous generation of life on Earth.
Pinching an idea from our sister blog, Prospero, we decided to ask Dr Hazen about his work in a less constrained interview format. He talked to us about the origin of life and its effect on Earth's geology.
Some 4.5 billion years ago Earth had just formed into something like a rough sphere. What did the surface look like? What was it made of?
Earth has undergone several radical transformations over its 4.5 billion-year history, and those transformations have altered its appearance in striking ways. If you go back 4.5 billion years, Earth is more or less its modern size, it's largely molten and it's "differentiated", meaning that its heavier metals have sunk to the core. It was just starting to form a crust, and there were huge volcanoes all over its surface. The volcanoes were quite volatile; they're spewing enormous amounts of water vapor, nitrogen and carbon dioxide, which will eventually coalesce to form the primitive oceans and the atmosphere. Essentially, Earth was this ball covered with a thin, black crust broken up by cracks and fountains of glowing red magma. It was quite different from the Earth we know today.
And this infant Earth did not yet have a moon. In your book, you discuss a relatively new theory for how the moon may have formed.
The formation of the moon is one of the enduring scientific mysteries. It has been around as long as people have and it has generated a host of folk stories and myths. Fifty years ago, there were three popular explanations for the formation of the moon. George Darwin, Charles Darwin's son, thought that the young Earth was once a molten orb, and that it rotated so fast that it sort of threw off a blob of magma that became the moon. There was also the capture theory, the idea that the moon was a small planet with a similar orbit to Earth, and that it was captured by the Earth's gravity billions of years ago. Others have argued that the moon formed from the same cloud of dust, gas and debris that formed Earth and the other planets that orbit the sun.
Ultimately it was the Apollo moon landing, and the rock samples that came out of it, that were critical to understanding how the satellite formed. Those rock samples were inconsistent with all three of the theories I just described, and they forced scientists to come up with other hypotheses. They did and, fortunately, it seems to fit all the observations and is really quite robust now, in terms of scientific consensus. It seems that there was, indeed, a second planet-sized object (probably about the size of Mars) in more or less the same orbit as Earth. We have a rule in astrophysics that no two planets can occupy the same orbit, and so inevitably the smaller-sized object would have collided with Earth. In collisions of that sort, the larger body always wins.
In other words, Earth essentially swallowed the smaller planet, which has come to be called Theia (for the Greek goddess, who was the mother of the Moon). But because it was a glancing blow—ie, the collision between Earth and the theoretical planet was slightly off center—a huge amount of molten and incandescent silicone vapor was blasted into space, and into orbit around Earth. That is the material that ultimately formed the moon. The collision hypothesis explains some of the interesting compositional features of the moon, which were revealed by the Apollo astronauts.
One of the things your book really drives home is the enormous role that life has played in changing Earth's geology. How quickly after life appeared did it begin to have these major effects?
This is a theme central to most of my research. I don't think people fully appreciate the extent to which life has played a role in geology, how the biosphere and the geosphere co-evolved. But it did take a long time for microbial life, which probably arose around 4 billion years ago, to have a substantial effect on Earth's surface. The early microbes acted as catalysts, accelerating chemical reactions on the surface, which was still quite volatile.
It wasn't until much later, probably in the last 2.5 billion-3 billion years that life learned the trick of using the sun's energy to produce oxygen via photosynthesis. Oxygen, when it starts getting pumped into the atmosphere, is a highly reactive and corrosive gas. It causes chemical reactions that would not have occurred on Earth's surface were it not for life. That was the big transforming event: the oxygenation of the atmosphere. It has completely altered Earth. I think it's fair to say that for the last 2.5 billion years, the story of this planet has been that of its oxygenation.
This began with the so-called great oxidation event. Oxidation evokes images of rust. Does that mean the surface of Earth may have once looked like the surface of Mars?
It is likely that early on the very outer surface of Earth looked reddish. It doesn't take very much oxygen to force iron atoms to give up an electron to some other atom—which turns iron into that rusty red color. That could have happened very early on. But the key thing is that it was only a very thin layer on the surface, like a coating of red paint—like Mars, which is not rusty red all the way through but only right at the surface. If you go down just a few centimeters below the surface of Mars, you will find an environment where there isn't much free oxygen around at all, and those rocks are going to have a very different character.
Earth is home to a tremendously diverse array of minerals, over 4,600 in all. Whence the diversity of mineral species?
The mineral richness of Earth goes back to this great oxidation event. We were amazed when we discovered this back in 2008—it was staring us in the face, but no one had ever put it together. What we did was ask ourselves how you get a new mineral. We realised that you can get them through some very classic processes with water and rock, and you can get evaporative minerals like salt when oceans dry up. But those processes only get you up to about 1,500 minerals.
It turns out, and this is what was so shocking, that two-thirds of all the minerals on Earth were formed as a consequence of the biosphere. They were the consequence of life, because life produces oxygen and oxygen then alters everything at and near Earth's surface. This creates literally thousands of new minerals that are simply the consequence of oxygen reacting with earlier generations of minerals. This process changed Earth in a way that no other known planet. Mars has maybe 500 mineral species; Mercury has no more than 350 mineral species. On Venus you might get up to 1,000-1,500. Earth's much higher tally is a consequence of life.
When you think of Earth as a whole, particularly the classic images of Earth from space, what immediately stands out are its oceans. Even when viewed from a distance, Earth is described a pale blue dot. When did Earth become a blue planet?
The questions as to when the oceans formed is still controversial, but there are several strong pieces of evidence that suggest Earth was almost entirely covered in blue very early on—some 150m years after its formation. For one, the early crust was really hot and therefore soft, which makes it difficult, if not impossible, to build high mountains. You would have no rocky mountain terrain like you see today in the Himalayas and elsewhere. The whole surface topography would have been rather uniform and flat. The only really high places would be volcanic cinder cones, and they would be spewing out huge amounts of water vapour which would, in turn, fall to the surface and form oceans that around the volcanoes. So there would be little volcanic islands on an otherwise blue planet.
We also have mineral evidence of early oceans. We don't have any rocks that go back 4.4 billion years, but there are these amazing single grains of a mineral called zircons, which are made from a very resilient mineral called zirconium silicate. If you look closely and carefully at these zircon crystals, and measure the ratio of oxygen isotopes in them, you can infer something about the temperature at which the zircon crystals formed. It turns out that the oldest Zircon crystals known, which are 4.4 billion years old, formed at a relatively cool 700°C. In order for those zircon crystals to crystallise at that temperature, they had to be in a very wet environment. Earth's surface must have been relatively cool and relatively wet at the time. This is the smoking gun argument for the early oceans.
In 1953 a graduate student at the University of Chicago named Stanley Miller did a famous experiment where he recreated the gases of Earth's early atmosphere in a glass bottle, and introduced sparks into it to stimulate lightning—the kind of lightning that some thought may have been responsible for nudging the primordial soup into action, generating the first life on Earth. The sparks generated a rich brew of amino acids, the building blocks of life. What have we learned since then about how life on Earth began?
In a lot of ways that experiment was the start of modern origin-of-life research. Since then, we have learned that the simple building blocks of life are produced anywhere you have carbon, oxygen, hydrogen, nitrogen and a source of energy. It can be on the floor of the ocean in deep volcanic hydrothermal vents where the chemical energy of rock causes chemical reactions; it can be high in the atmosphere; it can be a little tidal pool; it might even be in deep space, were ultraviolet light to irradiate these small molecules.
Miller's experiment was the first step in demonstrating that you can make amino acids, sugars, lipids, the building blocks of DNA and RNA (single-stranded copies of the double-helical DNA genes). There is no shortage of those ingredients for life. The big challenge today is figuring how you select, concentrate and assemble all of those molecules into a larger lifelike system, one which starts to make copies of itself. And that remains a huge mystery.
One of the newer theories of abiogenesis is the hydrothermal theory, which says that life was first generated in deep volcanic vents. What is compelling about this idea?
Some of it is sociological, the rest is scientific. For me, the scientific attraction is that all life today lives off an oxygen reduction reaction, a kind of chemical process that takes place in photosynthesis, where you take carbon dioxide and water and make organic molecules. And it isn't just plants—human beings do it too, breathing in oxygen and oxidising glucose in order to harness chemical energy.
In a deep-ocean-volcano system, the chemical energy present is identical to what you need for an oxygen reduction reaction. This is very different from the idea of lightning as the initial energy source. Lightning is very violent and can easily break molecules apart, scuppering attempts to concoct complex ones. That problem does not arise in the gentler hydrothermal scenario.
There another reason I like the hydrothermal hypothesis, and it's the same reason that NASA has been so supportive of our research. If you need lightning on the surface of a warm, wet planet, then Earth—and possibly Mars, in its first 500m years—are the only two places in the solar system where you can possibly hope to find life. But if you can expand your range to include deep hydrothermal zones where you have a a warm, wet environment deep underground, then big moons like Europa, Callisto and Titan, or even the polar reaches of Mercury, become places we can go looking for life.
Abiogenesis is a fairly controversial area of research. As you point out, it remains a mystery how you get from the building blocks of life to a self-replicating system like a cell. What would constitute bulletproof empirical evidence to settle the debate?
To me the holy grail of origin-of-life research would be to find, and demonstrate, a simple, geochemically plausible way of creating a group of molecules that spontaneously organise themselves to make its own copies. If you could do that in a laboratory setting, you could extrapolate it the early Earth. Remember that Earth is not like a laboratory with just a few test tubes; it has literally billions of square kilometers of reactive mineral surfaces, and hundreds of millions of years to get the results.
It also has this richness of organic molecules that are reacting to those surfaces. Earth is running an amazing number of experiments; I once calculated that if you have a hundred million years to play with on an Earthlike planet, you could run something like 1050,maybe even 1060 different chemical experiments. In a laboratory environment you are lucky if you can run three or four experiments in a year. So, if there were even the slightest possibility that some arrangement of molecules can assemble and start making copies of itself, Earth was going to find it.
It is hard to imagine an Earth without plants, but this greening is a relatively recent phenomenon, having occurred only 500m years ago. Most of the time Earth was ruled by microbes. Why did plants take so long to dominate the landscape?
This took a long time, for a couple of reasons. First, making multi-cellular organisms is quite complicated; it takes a lot of co-operation. You also need to have lots of oxygen, because without oxygen you lack an energy source that is compact and powerful enough to drive the kinds of reactions plants and animals rely on. Furthermore, you cannot have life on land until you have a protective ozone layer. Ozone concentrates high in the atmosphere, and acts like a sunscreen, absorbing harmful ultraviolet radiation. If there were no ozone in the atmosphere, the sun's ultraviolet radiation would be so intense that almost any living thing on the surface would have trouble surviving. And it takes billions of years to build up enough oxygen in the atmosphere to feed plants, and to create an ozone layer.
You write that certain parts of this story of Earth are subject to intense debate and could shift as science progresses. What parts of the story do you think are thinly supported—and most vulnerable to revision?
The further back in time you go, the greater the uncertainties. For instance, we still don't know exactly when life arose. Some people imagine that it arose shortly after the oceans formed 4.4 billion years ago, but the formation of the oceans is itself a matter of debate. When talking about the distant past, you won't always have a tonne of data. That means staking huge inferences on small piece of evidence, and tweaking those inferences when something doesn't quite match. Bits of the story can be explained by facts, but the rest requires you to conjure up different scenarios. A geologist is basically a storyteller. Indeed, that is what makes the whole thing so much fun. | 0.854525 | 3.627901 |
Where neutrinos come from
Russian researchers trace high-energy neutrino origins to black holes in far-off quasars
Russian astrophysicists have come close to solving the mystery of where high-energy neutrinos come from in space. The team compared the data on the elusive particles gathered by the Antarctic neutrino observatory IceCube and measured with radio telescopes in the long electromagnetic waves. Cosmic neutrinos turned out to be linked to flares at the centers of distant active galaxies (quasars), which are believed to host supermassive black holes. As matter falls toward the black hole, some of it is accelerated and ejected into space, giving rise to neutrinos that then coast through the Universe at nearly the speed of light.
The result has been obtained thanks to the long-term measurements of more than one thousand quasars with the RATAN-600 radio telescope (the Special Astrophysical Observatory of the Russian Academy of Sciences). The RATAN-600 is one of the largest radio telescopes in the world. Due to its possibility to record quasi-simultaneous radio spectra at different radio frequencies, a unique experimental material has been obtained which allows establishing a connection between the ultra-high energy cosmic neutrinos (200 trillion electron volts or more) and quasars' flare activity. The observational data have been analyzed by the astrophysicists of the Lebedev Physical Institute of RAS, the Moscow Institute of Physics and Technology and the Institute for Nuclear Research of RAS.
The study is published in the The Astrophysical Journal and is also available from the arXiv preprint repository. The scientists revealed that the areas where high-energy neutrinos come from coincide with the locations of bright quasars.
The elusive particles have been found to emerge during radio flares at the centers of quasars.
"Previous research on high-energy neutrino origins had sought their source right 'under the spotlight'. We thought we would test an unconventional idea, with little hope of success. But we got lucky!" Yuri Kovalev from the Lebedev Institute commented.
Neutrinos are mysterious particles so tiny that researchers do not even know their mass. They pass effortlessly through objects, people, and the entire Earth. The principle of the IceCube observatory operation is based on this neutrino property – only neutrinos can pass through the Earth. High-energy neutrinos are created when protons accelerate to nearly the speed of light. The IceCube observatory detects such neutrinos and estimates their energy and incoming direction.
The detection of ultra-high energy neutrinos coming from quasars opens a new stage of multi-messenger astronomy and confirms the idea that quasars are potential sources of these particles. Studying electromagnetic radiation, gravitational waves, and elementary particles comprehensively, multi-messenger astronomy is one of the most topical areas of up-to-date astrophysical research. At present, the intensity of quasar observations with RATAN-600 have increased, as it became clear it could be a key to the nature of neutrinos. Due to the new IceCube neutrino detections in 2020, the observations and analysis of such events with RATAN-600 are ongoing.
The Special Astrophysical Observatory of the Russian
Academy of Sciences, phone: 8-878-22-93-305 | 0.835601 | 4.101082 |
He is a trained geophysicist and, even as a child, he was passionate about natural phenomena – particularly the stars – before fulfilling his dream of reaching for the stars with his first journey into space in May 2014. He began his career as a volcanologist and spent time working at research stations in the Antarctic and elsewhere, unknowingly training to develop the characteristics that would later benefit him in the selection process run by DLR, the German Space Agency. Even at this early stage of his career, he had to prove himself as a researcher in a hostile environment, surrounded by volcanoes and glaciers and far from civilisation. In the meantime, even though his job has changed somewhat, Alexander Gerst continues to travel and work in a hostile environment. Among the stars and planets, with temperatures that range from -156 to +121 degrees Celsius, he orbits the earth in the ISS, working for ESA, the European Space Agency.
The ISS has been orbiting the earth, as a continuously manned space station at around 400km above the earth. It is a technological milestone that features the latest technologies and that is constantly engaged in research missions to address the challenges that the earth faces. The Russian space station, MIR, continues to be recognised as a predecessor of today’s ISS; that space station was in orbit from 1986 until 2001 and made substantial contributions to the current state of space research.
When construction of the ISS started in 1998, it marked the beginning of the end for MIR, with the older space station eventually being brought back to earth in a controlled descent, which ended with it burning up in the earth’s atmosphere after 15 years of service. As a unique space project, supported by NASA, ESA, Roscosmos, CSA und JAXA, the ISS orbits the earth at a speed of 28,000 km/h, meaning that it takes just 93 minutes to complete an orbit. The International Space Station is an orbital research facility and is occupied by a scientific team or astronauts all year round. During the initial stages of its mission, the focus was on completing maintenance work and modifications to the space station before any research could be carried out. The crew that is currently on board the space station, Andrew Jay Feustel, Richard Robert Arnold and Serena Auñón-Chancellor from the USA, Oleg Germanovich Artemiev and Sergei Valerievich Prokofiev from Russia, and Alexander Gerst from Germany, is the fifty-sixth to travel to the space station.
A plethora of different research projects are pursued on the ISS, day in and day out. As well as experiments to examine changes in physical properties of specific materials and biological processes in the growth of plants, the human body also serves as a subject of these experiments.
Myotonia is an umbrella term that covers a range of conditions including muscular tension, muscular wasting, and their associated symptoms. Myotonia is not necessarily a medical condition from the outset; however, when tension becomes chronic, its effects extend to the entire body and lead to anatomical deformities. However, what is the influence of weightlessness on the musculoskeletal system and how can these findings be used on earth?
In space, very little strain is placed on muscles in order to move, as there is no need to overcome gravity, which would take muscle power. This leads to a continuous loss of muscle. Astronauts must therefore attempt to retain their muscle mass; otherwise it would be extremely challenging for them to return to earth. This means that they have to spend two hours per day working out to prevent muscle loss, while the current mission is using new technology to carry out a scientific analysis of changes to the muscles in space.
MyotonPRO is a device, about the same size as a smartphone, and which uses a pulse generator to send a gentle wave of pressure through the tissue. By recording the oscillation of the skin as a result, even the smallest changes in muscle structure can quickly and effectively be measured and analysed. Data from these experiments is ultimately processed in universities and research institutes to create early medical diagnoses and to develop new treatment methods. Space is the ideal environment for these experiments, as it is extremely difficult to induce artificial muscle wasting on earth.
Experiments at temperatures close to absolute zero (0° kelvin or -273.15° Celsius), whereby atoms scarcely move at all, also form part of the current ISS research mission. In the Cold Atom Laboratory (CAL), atoms can be decelerated to a temperature of one billionth of a degree above zero kelvin. More heat means more speed, and thus, more energy. Particle deceleration means using laser cooling to bombard atoms with photons against their direction of travel. The atoms absorb the photons, slowing down their movement, and creating the cooling effect. As absolute zero approaches, a new form of matter is created: the Bosen-Einstein condensate. In this state, individual atoms can no longer be localised, as the deceleration results in a wave of atoms (which is a surreal notion, but one that is found in reality, both on earth and in space).
In the weightless environment of space, these experiments can be formed without the influence of gravity, as the earth’s gravitational pull would otherwise create a distorted wave pattern, or mean that the condensate could only exist for a few seconds.
As a result of the CAL research project, scientists expect new research approaches to materials and gravitation to be developed to expand the boundaries of what is physically possible. Similarly, the findings from these experiments could lead to the development of new techniques to transfer energy or help to optimise sensor technologies.
These are exactly the people that ARTS supports: people who have innovation and vision in abundance. Something that seems inconceivable today could become tomorrow’s reality; however, following your dreams and reaching for the stars means daring to take a step forwards. Just like the scientist, Alexander Gerst on the ISS, ARTS uses its expertise in the aviation and aerospace industries, as well as high-tech sectors such as the automotive and light engineering industries, to support further development and optimisation. From turnkey project management solutions, through to technical consultancy and providing the services of expert minds – we help you to achieve the advances you need to make your project success.
Extending your success: this motto applies to our clients every bit as much as it does to our staff. | 0.824791 | 3.174176 |
Astronomers have long believed that they knew how planets were formed, but now they think they’ve spotted one being born far out in space.
In the constellation of Auriga, a star system that’s easily spotted from Earth during the autumn and winter, lies a young star called AB Aurigae.
The star, some 530 light-years from Earth, is surrounded by a spiral cloud of dust and gas.
This spiral gas cloud is marked by a “twist” that, scientists say, marks the spot where a planet is starting to form.
The twist is about as far from AB Aurigae as the planet Neptune is from our own Sun.
Planet formation is thought to take place in the first million years of a planetary system’s existence, so the entire star system is likely to be much younger than our own Solar system.
Images captured by the European Southern Observatory’s Very Large Telescope (VLT) have been sent back to the Observatoire de Paris at the PSL University, in France.
A team of astronomers used the VLT’s extreme adaptive optics system, SPHERE, to study the disturbances in the gas cloud.
Dr Anthony Boccaletti, who led the research into the baby planet, said: “Thousands of exoplanets have been identified so far, but little is known about how they form.”
He added: “We need to observe very young systems to really capture the moment when planets form.”
One Dr Boccaletti’s colleagues, Anne Dutrey from the Astrophysics Laboratory of Bordeaux, said that the phenomenon that they have seen agrees with scientific predictions about how planets form: “The twist is expected from some theoretical models of planet formation.
It corresponds to the connection of two spirals – one winding inwards of the planet’s orbit, the other expanding outwards – which join at the planet location.”
In time the twist is expected to condense into a ball of super-dense gas giving birth to a gas-giant planet, which might one day be named by future humans. | 0.91139 | 3.535162 |
May 02, 2013
Image of the Day: Sunset on Osiris (Exo-Planet HD209458b)
The amazing image above of a sunset on exo-planet HD209458b 150 light years away, was reconstructed by Frederic Pont of the University of Exeter using data from a camera onboard the Hubble Space Telescope .
Pont used his knowledge of how the color of light changes based on
chemicals it encounters, and computer modeling, to create an actual
image of what a sunset on the actual planet would look like.
The large exo planet in question, exoplanet HD209458b, nicknamed Osiris ,
circles its star rather closely. At certain points, when the planet
passes between us and its star, the light from that star passes through
Osiris’s atmosphere before reaching us, which allowed Pont to determine
the chemical composition of the atmosphere and deduce what colors would
appear to the naked human eye.
The light from Osiris’s star is white, like our own sun, but when it
passes through the sodium in Osirisi’s atmosphere, red light in it is
absorbed, leaving the starlight to appear blue. But as the sun sets, the
blue light is scattered in the same way as it is here on Earth (Rayleigh scattering )
causing a gradual change to green, and then to a dim dark green. And
finally, due to diffraction, the bottom of the image becomes slightly
The Daily Galaxy via Hubble/ESA and Frederic Pon
Image of the Day: Sunset on Osiris (Exo-Planet HD209458b) .
Thanks to: http://2012indyinfo.com | 0.821635 | 3.048118 |
Its exquisite images have graced the pages of astronomy books and calendars all over the world and provided astronomers with invaluable information on the mysteries of the universe.
Now, after 19 years orbiting hundreds of miles above Earth's surface, the Hubble Space Telescope is getting its fifth and final makeover, with a slate of new instruments and repairs scheduled that will restore and expand some of the iconic telescope's capabilities.
The astronaut crew that will give Hubble its tune-up will launch aboard the space shuttle Atlantis on May 11 for an 11-day mission. The excitement over the mission and Hubble's capabilities afterward is palpable among NASA scientists.
"If we are successful, [Hubble] will be more powerful and robust than ever before and it will continue to enable world-class science for at least another five years," said Ed Weiler, associate administrator of NASA's Science Mission Directorate in Washington, D.C.
With those added five years, "we'll be entering our second quarter century on Hubble — that's not bad for a mission we hoped would last 10 to 15 years," Weiler added.
In those five extra years, scientists will use Hubble to peer back closer to the beginning of the universe, look for more exoplanets and try to help solve the mysteries of dark matter and dark energy.
Hubble is badly in need of the repairs and upgrades planned for this month.
"It's been seven years since we've serviced the Hubble Space Telescope," said David Leckrone, Hubble project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. That's "twice as long as we should go in terms of servicing intervals. As a consequence of that, over the last few years, we've seen significant deterioration within the set of scientific instruments that we provide to the astronomical community."
One of the instruments the astronauts will try to fix is Hubble's Advanced Camera for Surveys (ACS), which has been hobbled in recent years. It has three so-called channels, which each act as a separate instrument and have different capabilities: the wide-field channel (the most heavily-used), the high-resolution channel, and the solar blind channel.
Scientists can choose which they want to use based on the kind of science they want to do. But currently on the solar blind channel is working.
"In a sense the ACS is still working, but only on one of its three channels," Leckrone said.
The spacecraft's Space Telescope Imaging Spectrograph (STIS) also has three channels, none of which are currently working. If time allows, the astronauts will try to revive its three channels.
The STIS and ACS repairs are complicated circuitry work not designed to be done in space, so mission scientists can't be sure how the repairs will turn out, though they are optimistic about the chances.
But, if the team can't complete the ACS repairs, then the instrument will still be left with the solar blind channel, "so we should be no worse off there than we were before," said Hubble project manager Preston Burch, of NASA's Goddard Space Flight Center in Greenbelt, Md.
Also, the brand new Cosmic Origins Spectrograph will augment STIS's capabilities; it has 2 channels, one for near ultraviolet observations and one for far UV. COS can also stand-in for STIS if can't get it repaired
Also joining the Hubble instrument team will be the Wide Field Camera 3, which will replace the Wide Field Planetary Camera 2 and complement ACS's observing capabilities (it can also observe in the same wavelengths of light as ACS if ACS can't be repaired).
Wide Field Planetary Camera 2 "has been operating like a champ for about 15 years now, but it is getting a little bit long in the tooth and will be replaced on this mission," Leckrone said.
All of these instruments are "tremendously important tools to be used for a broad variety of astronomical investigations," Leckrone said.
When this servicing mission is complete (and if all goes according to plan), "Hubble will be at the apex of its capabilities," Leckrone added "It will never have been better before than it will be at that point."
What will Hubble do now?
Once its newly-tricked out, Hubble will be able to take even more images and continue to add to our knowledge of the universe.
In the nearly two decades it has been operational, Hubble has contributed considerably to our understanding of the universe.
In an essay in the Jan. 1 issue of the journal Nature, astronomer Julianne Dalcanton, of the University of Washington, discussed some of the contributions Hubble has made, including: refined distance scales in the universe (by monitoring Cepheid variable stars); the life cycle of stars (including the first observations of proto-planetary disks around stars); a better understanding of black holes and their role in the formation of galaxies; the formation of the first galaxies (through the Hubble Deep Field and Ultra Deep Field); and the general age, composition and size of the universe .
"We have reformulated so many different areas of astronomy," Leckrone said. "There is no area of modern astronomical research that hasn't been profoundly affected and changed by Hubble."
With its new components, Hubble will continue to do science in these many of these areas, with the hopes of shedding even more light on the dark spots of space.
Hubble will further investigate the architecture of the universe, as well as the structure of individual galaxies.
"Hubble will look all the way from the nursery to the old age of galaxies," Leckrone said.
When Hubble took its first look back in time, scientists expected to see infant galaxies, because it was thought to take at least a billion years for galaxies to form.
"And lo and behold, what did we see? Did we see the first babies coming out of the birth canal? No, we saw three-year-olds, five-year-olds, ten-year-olds, we saw galaxies already well-formed at a billion, two billion years, which implied that the universe didn't read the same textbooks and decided to get its act together much, much, much earlier than any physicist thought it could," Weiler said.
With the Ultra Deep Field, Hubble was able to spy on galaxies that formed when the universe was only about 700 million years old. With the new Wide Field Camera 3's infrared channel, astronomers will be able to take another survey and stretch our view even further (before the James Webb Space Telescope takes over in this arena).
"I guess you could now call it an Ultra Ultra Deep Field, which hopefully will press back another couple of hundred million years, and we'll perhaps see even earlier fledgling galaxies that emitted their light within, say, 500 million years of the Big Bang," Leckrone said.
Within galaxies, Hubble will investigate how stars are born.
"It's not just something that happened long ago and stopped, continually stars are being born within galaxies and they evolve, burn out their nuclear fuel and ultimately die," Leckrone said. "And understanding that whole process is something that we are now capable of doing, not only in our own galaxy, but in other galaxies as well as we study stellar populations."
Hubble will also likely extend its unexpected contributions to the study and search for exoplanets.
"Hubble surprised everybody by being able to actually observe the atmospheres of planets around other stars and get information about their chemical composition and structure," Leckrone said. "We never expected to be able to do that, but we will continue to do that in a very serious way after this mission."
The telescope will also continue its quest to help solve the mysterious entities of dark matter and dark energy.
"Hubble will of course continue to survey supernovae going off in the distant cosmos to try to narrow down the uncertainty in the quantitative understanding of the magnitude of dark energy," Leckrone said.
But as stunning as the findings of any of these efforts might be, mission controllers say it's probably something unexpected that might be Hubble's triumph in its last few years.
Beginning of the end
Hubble won't be taking pictures again immediately after its facelift, but from the time the astronauts release Hubble back into orbit, "you can start a clock at that point," and expect that after nine or 10 weeks its instruments will be "back up and running and ready for science," Leckrone said.
Mission scientists are aiming to have the first public release of images in early September, he added.
How long the telescope will last after that isn't known for sure, and depends on how Hubble holds up with no more astronauts coming to fix it and whether astronomers are still interested in using it.
"The five years we think we have a good shot at," Burch said. "I would think there's probably a very good prospect of even seven years, like we've currently gone past." | 0.817968 | 3.404488 |
Earth’s water is older than the Sun
Around 70 percent of the Earth’s surface is comprised of water, and our big, blue, planet is filled with rivers, streams, and oceans that defy everything scientists have come to learn about the formation of Earth.
Unraveling the mystery of Earth’s water is no easy task as there are so many unknown variables in the formation of the planet.
Most scientists agree that Earth got its water from comets and asteroids carrying an array of compounds, organic matter, and precious metals. As these comets bombarded the Earth, they brought with them the building blocks for our world’s water cycle.
The question is, when did water first make it to Earth? Was it during Earth’s early formation, when a ring of gas and space debris circling the sun melded together to form the solar system? Or was it after the collision that later formed Earth’s moon?
Natalie Starkey, a researcher from Open University in Milton Keynes, has found evidence to suggest that Earth’s water is older than even the sun and dates back far earlier than what was previously theorized.
Starkey and colleagues are working to solve one of Earth’s oldest mysteries by studying ancient rock samples from the boundary between the Earth’s core and mantle.
In an article for New Scientist, Starkey describes the pockets of gas contained within the rocks as “time capsules” that shed light on what the atmosphere was like billions of years ago.
The researchers used a precision mass spectrometer to separate and measure the oxygen isotopes in the rock samples and moon rock samples in the hopes of gaining a better understanding of when water first came to Earth.
By comparing moon rock samples and samples from Earth’s mantle, the team was able to confirm that the Earth and Moon are made up of the same components.
This means that the theory that a collision caused the Earth to break apart and some pieces formed the moon is most likely accurate.
The researchers also discovered that at least 70 percent of Earth’s water was present before that collision and before the moon formed. This revelation simply created more questions than answers.
The chaotic maelstrom of the Hadean Eon, when the Earth was a hot glowing mass of molten material, would have made it impossible for water trapped within comets and asteroids to survive the hot temperatures.
Logic dictates that any isotopes carried within comets should have been broken up into constituent atoms when it reached the solar system because of the extreme radiation of the sun.
Yet, Starkey says that survive they did, and it’s the only explanation that fits. It’s been theorized that there was a small window of time when the sun was cooling off and before the planets formed that interstellar ice could have slipped into the mix.
“That brings us to the surprising conclusion that our planet’s water isn’t just older than the moon,” Starkey writes. “It must have come from interstellar space, which means it is older than the sun itself. It is hard to fathom how it survived entry into the solar system. But once you have eliminated the impossible, it forces you to this conclusion.” | 0.804106 | 3.451562 |
This month marks the third anniversary of the discovery of a remarkable system of seven planets known as TRAPPIST-1. These rocky, Earth-size worlds orbit an ultra-cool star 39 light-years from Earth; 1 light-year is approximately 5.88 trillion miles.
Three of the planets are in the “habitable zone,” meaning they are at the right orbital distance to be warm enough for liquid water to exist on their surfaces. NASA’s James Webb Space Telescope will observe those worlds after its launch in 2021, with the goal of making the first detailed, near-infrared study of the atmosphere of a habitable-zone planet.
Numerous Cornell astronomy faculty will contribute to the mission. Nikole Lewis, assistant professor of astronomy and the deputy director of the Carl Sagan Institute, is the principal investigator for one of the teams investigating the TRAPPIST-1 system.
“It’s a coordinated effort because no one team could do everything we wanted to do with the TRAPPIST-1 system,” Lewis said. “The level of cooperation has been really spectacular.”
Lewis’ team will observe one of the planets, TRAPPIST-1e, in an effort to not only detect an atmosphere, but also to determine its basic composition. They expect to be able to distinguish between an atmosphere dominated by water vapor and one composed mainly of nitrogen (like Earth) or carbon dioxide (like Mars and Venus).
TRAPPIST-1e is one of the known exoplanets having the most in common with Earth; its density and the amount of radiation that it receives from its star make it a great candidate for habitability. Lewis will also lead 130 hours of guaranteed time observations focused on the detailed study of exoplanet atmospheres with Webb.
Ray Jayawardhana, the Harold Tanner Dean of Arts and Sciences and professor of astronomy, and Lisa Kaltenegger, associate professor of astronomy and director of the Carl Sagan Institute, are part of a team that will dedicate 200 hours of time on the Webb telescope to characterize exoplanets, including Trappist-1d (a hot, rocky, Venus-like planet) and Trappist-1f (a cooler, Earth-size planet).
“We look forward to ‘remote sensing’ a remarkable diversity of exoplanet atmospheres, ranging from temperate terrestrial worlds in the TRAPPIST-1 system to blazing gas giants orbiting very close to their stars,” Jayawardhana said. “The Webb telescope will give us unprecedented views, especially of the smaller planets that are tougher to probe.”
Added Kaltenegger: “The combination of the data from the three TRAPPIST planets will give us unprecedented insight into how rocky planets evolve at different distances from their host star. It is the best laboratory that we could have asked for, to get insights into how extrasolar rocky planets work.”
Jonathan Lunine, David C. Duncan Professor in the Physical Sciences and chair of astronomy, is the interdisciplinary scientist for astrobiology on the Webb mission and serves on the Science Working Group, which defines the mission’s science requirements and provides scientific oversight of the project. His hours on the telescope will be mostly used to look at “hot Jupiters” – gas giant planets that are very close to their stars – and Kuiper Belt objects.
James Lloyd, professor of astronomy, developed the Aperture Masking Interferometry mode of the telescope’s Near-Infrared Imager and Slitless Spectrograph (NIRISS) instrument, which will be used to image planetary systems and their environments.
The Webb telescope will be the world’s premier space science observatory, able to solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the enigmatic structures and origins of our universe. Webb is an international program led by NASA, with partners the European Space Agency and the Canadian Space Agency. | 0.861703 | 3.765675 |
X-rays reveal how cosmic giants meet
24 June 2019Scientists have uncovered an extremely powerful shock wave in a distant part of the Universe where two massive galaxy clusters appear to come into first contact ahead of merging. The study is based on data from several astronomical facilities, including ESA's XMM-Newton X-ray space observatory.
|Merging galaxy clusters at first contact. Credit: NASA/CXC (X-rays); SDSS (optical); GMRT (radio); Liyi Gu et al. 2019|
According to Liyi Gu, an astronomer from RIKEN High Energy Astrophysics Laboratory in Japan and the Netherlands Institute for Space Research, who is the lead author of a paper published today in Nature Astronomy, the observations capture the unique moment when the two clusters touch each other for the very first time – something that has never been observed before.
The clusters, called 1E2216 and 1E2215, are located over one billion light years away from the Earth and have been drawn towards each other by gravity for billions of years. Their first contact, indicated by the new data, marks the beginning of a dramatic and lengthy process that will completely mix the clusters up and combine them into one.
"Collisions between galaxy clusters are the most energetic events in the Universe since the Big Bang," said Liyi. "The shocks that arise during the merger are probably the most important particle accelerator in the Universe, releasing a huge amount of heat, radiation and high-energy cosmic rays."
|Sequence of merging galaxy clusters. Credit:
click image for credit details.
Clusters of galaxies are the largest known objects in the cosmos bound by gravity, and can consist of hundreds of galaxies, each containing billions of stars or more. Interspersed between a cluster's galaxies are huge amounts of hot, X-ray emitting gas, and even larger amounts of the invisible dark matter.
These enormous cosmic objects are thought to form gradually, starting first with individual galaxies encountering each other due to the effects of gravity. The process continues with the formation of smaller groups, which then merge into bigger and bigger clusters. While the first touch, the so-called pre-merger phase, lasts for a relatively short period of time – around 100 million years – the entire merging process takes billions of years to complete.
Liyi and collaborators around the world gathered about 40 hours of observations with ESA's XMM-Newton in 2017 and another 40 hours with NASA's Chandra X-ray telescope in 2018. These observations were combined with 2012 data from JAXA's now decommissioned Suzaku satellite and with radio data from two ground-based telescopes located in Europe and India.
The scientists think that the data reveal a pre-merger shock caused by the first contact between the two clusters.
|Shocks during galaxy cluster merger. Credit: Courtesy of H. Akamatsu (SRON)|
In the observations, they could distinguish two very hot gas halos with temperatures in excess of 50 million degrees Celsius, each associated with either cluster, and connected by a bridge of even hotter gas.
"This gas bridge is shock-heated: on the two sides you can see a shock front propagating from the inside out along the equatorial plane of the merger," explained Liyi. "The bridge was created by the merger itself. As the two clusters are getting closer, at some point they start getting connected."
|Temperature distribution of merging galaxy clusters IE2216 and IE2215. Credit: ESA/XMM-Newton; GMRT; Liyi Gu et al. 2019|
Liyi added that it was somewhat surprising to see the shock wave propagating outwards along the equatorial plane, as most shocks found in merging galaxy clusters usually propagate along the vertical axis of the merger. However, theoretical models and numerical simulations do predict that a similar phenomenon might occur during the pre-merger phase.
"The equatorial shock can be explained simply by a very strong compression along the merger axis," said Liyi.
In particular, XMM-Newton enabled the scientists to calculate the temperature distribution of hot gas within the two clusters, as well as the extremely high temperature in the shock region, reaching up to 100 million degrees Celsius.
"From the XMM-Newton data, we could estimate the shock speed and the total dynamic energy of the system, including its pressure," said Liyi.
The team is planning to keep monitoring this cosmic encounter with XMM-Newton and Chandra.
In coming years, XMM-Newton can be used to identify more cluster mergers like this one via dedicated observations of carefully selected portions of the sky. Next-generation X-ray observatories, such as the Japanese-led XRISM and ESA's Athena missions, will enable astronomers to learn in even greater detail what is happening during these gigantic collisions.
"We have been very lucky to have seen this first encounter between the two clusters," said co-author Jelle Kaastra from the Netherlands Institute for Space Research.
"Usually, we can see galaxy clusters getting closer to each other or already in the process of merging. With the next generation of X-ray telescopes, such as XRISM and Athena, we will be able not only to see more details of this particular merger but also find many more systems that are in different merging phases."
XRISM, a collaboration between JAXA and NASA including ESA participation, is scheduled to launch in 2021. Athena, part of ESA's Cosmic Vision programme, is expected to launch in 2031, and will carry instruments one hundred times more sensitive than those aboard Chandra and XMM-Newton.
Galaxy cluster mergers are among the most important processes that shape the structure of the Universe on very large scales. Yet, these giant collisions are poorly understood. With the facilities of the coming decades, scientists will be able to observe more such events at various stages and eventually piece together a complete 'movie' of the merging of galaxy clusters.
"Galaxy cluster mergers are difficult to observe because the timescales involved are so long," said Norbert Schartel, XMM-Newton project scientist at ESA.
"It will take a long time to fully understand these processes. We are just getting started by collecting data about mergers at different stages, and it is exciting that XMM-Newton could help capture the beginning of such a clash."
Notes for editors
The results described here are reported in "Observations of a Pre-Merger Shock in Colliding Clusters of Galaxies" by Liyi Gu et al., published in Nature Astronomy.
The study is based on X-ray data from ESA's XMM-Newton, NASA's Chandra X-ray telescope and JAXA's Suzaku satellite, along with radio-wave observations from the Low-Frequency Array (LOFAR), located in the Netherlands and other European countries, and from the Giant Metrewave Radio Telescope, located in India.
The team involves scientists based in Japan, the Netherlands, Australia, Germany, Hungary, the UK, India and South Africa.
For more information, please contact:
RIKEN High Energy Astrophysics Laboratory, Japan
SRON – Netherlands Institute for Space Research
Utrecht, The Netherlands
Jelle S. Kaastra
SRON – Netherlands Institute for Space Research
Utrecht, The Netherlands
XMM-Newton Project Scientist
European Space Agency | 0.880232 | 3.972845 |
PicSat will be launched into Earth orbit on 12 January 2018 to study the star Beta Pictoris, its exoplanet and its famous debris disk, thanks to a small telescope 5 cm in diameter. The nanosatellite has been designed and built in a record time of just three years by scientists and engineers at the Paris Observatory and the CNRS, with support from the Université PSL, the French space agency CNES, the European Research Council and the MERAC Foundation.
It is no bigger than three apples stacked upon each other, or rather three cubes, each 10 centimetres in size. It is not heavier than a cat (3.5 kg). It uses about 5 Watt of power, equivalent to that of an economical light bulb. Its telescope is only five centimetres in diameter, much like that of a young amateur astronomer. And yet, this nanosatellite seeks to improve our knowledge of the Beta Pictoris star system, a real “star” in the sky of the Southern Hemisphere.
Beta Pictoris lies merely 63.4 light years from the Earth. It is a very bright star, which makes it an easy target for study. This is quite fortunate, because with only 23 million years of age this star is very young astronomically speaking, and it has been a very popular object of study for scientists ever since the discovery in the 1980s of a massive disk of dust, gas and debris surrounding it. This disk, left-over from the gas cloud from which the star itself formed, is a rather rare object and astronomers worldwide have been scrutinizing it ever since. Indeed, better understanding Beta Pictoris means elucidating the formation of giant planets and planetary systems in general. In 2009, a French team led by Anne-Marie Lagrange1 found a giant gas planet, dubbed Beta-Pictoris b, seven times more massive than Jupiter, orbiting the star at 1.5 billion kilometres, similar to the distance planet Saturn orbits the Sun.
Seen from the Earth, the exoplanet Beta Pictoris b could be passing in front of its star between now and the summer of this year. By observing this transit phenomenon, which repeats itself every 18 years, astronomers could derive the exact size of the exoplanet, the extent of its atmosphere, as well as its chemical composition. However, the transit of the exoplanet will only last a few hours. To be able to observe the phenomenon, the exact timing of which is now known, the star has to be monitored continuously. This can only be done from Space, where there is no interruption due to the cycle of day and night, or the passage of clouds.
To attempt to observe the transit from Space, only a small, light nanosatellite could be developed in a short enough period of time. PicSat has been designed and built in only three years. This has been possible thanks to the use of existing cubic modular structures, a CubeSat structure, which is a standardised format developed in the US, initially for educational use.
For the French CNRS, as well as for the Paris Observatory, this is the first satellite designed and built entirely in-house. PicSat is born from an idea by Sylvestre Lacour, astrophysicist at the CNRS, in collaboration with Alain le Lecavelier des Etangs from the Institut d'Astrophysique de Paris (CNRS/Sorbonne Université), who has been working on the Beta Pictoris system for many years. Sylvestre Lacour made the project come true in his laboratory, Lesia (Observatoire de Paris - PSL/CNRS/Sorbonne Université/Université Paris-Diderot) with a small team of scientists and engineers. It is a completely new approach to space instrumentation that has now taken off for French space research. The technological developments for PicSat have been supported in the framework of the C2ERES Space Campus of the Université PSL, also at the site of the Paris Observatory in Meudon, France. The project has been made possible thanks to the financial support of the European Research Council (ERC), as well as that of the French CNRS, the Labex ESEP2 and the Swiss MERAC Foundation as part of its program to support young researchers in the field of Astrophysics.
On Friday 12 January 2018 at 4h58am local Paris time, the Indian PSLV launcher will lift off and place PicSat in a polar orbit at an altitude of 505 km, together with about thirty other satellites. PicSat will be operated from Lesia in Meudon. However, the satellite will be visible from Meudon for only about 30 minutes every day, when it passes over Paris. Therefore, PicSat uses radio amateur bands for its communication, for which authorisation has been obtained thanks to the help of the French Réseau des Émetteurs Français (REF, or the Network of French Emitters). Anybody who owns a minimum radio receiving equipment can listen to and receive PicSat's transmissions. The PicSat team invites radio amateurs from all over the world to collaborate in following the satellite, receiving its data and relaying them to the PicSat data base via the Internet. Those interested can register on the PicSat website at PicSat.obspm.fr to follow the updates and, if they so wish, become part of the radio network.
The nominal PicSat mission will last for one year. When the start of a planetary or other transit is observed, the 3.6-meter telescope from the European Southern Observatory in La Sille, Chile, will also be immediately put into action to observe Beta Pictoris using the powerful HARPS instrument. These data combined will allow an even better understanding of the phenomenon.
This release was first published 10 January 2018 by CNRS. | 0.851742 | 3.957558 |
Ancient Assyrian stone tablets represent the oldest known reports of auroras dating more than 2,500 years ago.
The descriptions, written in cuneiform, were found on three stone tablets dating from 655 B.C. to 679 B.C. They submit other known historical references to auroras by about a century ago, researchers reported in a new study.
Auroras are dazzling light shows that take place when waves of charged particles from the sun collide with Earth's magnetic field. Earth was likely visited by an immense solar storm around the seventh century B.C., and the auroras described in the tablets may have been the result of that powerful solar activity, the study authors wrote online Oct. 7 in The Astrophysical Journal Letters .
Related: Northern Lights: 8 Dazzling Facts About Auroras
Ancient Skygazing Accounts , help scientists piece together a more complete picture of Earth's cosmic tango with its solar partner. Because telescope observations have been around for 400 years, they provide "only a very small snapshot at best" of how our sun behaves, said lead study author Hisashi Hayakawa, an astrophysicist at Osaka University in Japan and a visiting researcher at Rutherford Appleton Laboratory in the United Kingdom
Earlier this year, another team of researchers found that a massive solar storm, about 1
The authors of a new study won if Assyrian astrologers from that period might have recorded anything unusual that could be linked to the solar storm . The researchers investigated 389 reports on cuneiform tablets in the collection of the British Museum; most of the reports described planetary and lunar activity. But three records noted phenomena that were likely candidates for auroras: "red glow," "red cloud" and "red sky," according to the study.
"These descriptions themselves are quite consistent with the early modern descriptions of auroral display , "Hayakawa told Live Science in an email. Indeed, red is a color commonly found in low-altitude auroras and in auroras produced by low-energy electrons, the researchers reported.
Today, auroras in the Northern Hemisphere are usually associated with regions close to the North Pole. But Earth's magnetic field is dynamic and changing, and thousands of years ago, magnetic north was about 10 degrees closer to the Middle East than it is today, increasing the likelihood of spectacular aurora displays in that part of the world, the study authors reported.
And even during the late 19th century, auroras were still glimpsed in Cairo; Baghdad; and Alexandria, Egypt, Hayakawa added.
"When you have significant magnetic storms, it is not something extremely surprising to see aurorae in the Middle East, even in the (early) modern period," Hayakawa said.
The infrequency of those descriptions in Assyrian records suggested that what writers had witnessed was something out of the ordinary and not, for example, a reddened sky that might accompany a vivid sunset, Hayakawa said.
Prior to this discovery, the earliest known reference to an aurora was in a Babylonian tablet known as the "Astronomical Diaries," dating to 567 B.C. The Assyrian records "allow us to trace the history of solar activity back a century earlier than the earliest existing datable auroral reports," according to the study.
Originally published on Live Science . | 0.821528 | 3.71478 |
DMI image reference Sco_2. « Previous || Next » Constellations A » H || Constellations I » V
Roll mouse over picture to see constellation figures and outlines
Image and text ©2008 Akira Fujii/David Malin Images.
In the picture above, top right is north and the image covers 27.8 x 34.8 degrees.
Image centre is located at 16:40:20.0, -25:25:30 (H:M:S, D:M:S, J2000) Astrometric data from Astrometry.net.
Best seen in the early evening in July
Scorpius is one of the few constellations whose star pattern resembles its name. The curved stinging tail is marked by the star Shahula, probably from from the Arabic 'Al Shaulah' meaning 'raised tail', as seen in a scorpion. In the body of the scorpion lies Antares, meaning 'rival of Mars' for its reddish colour. The head of the scorpion is echoed in the star name Dschubba, meaning 'forehead'. However, the scorpion shape looks trucated in our photograph and it is. In ancient times it extended into what is now Libra, where the brightest stars (not seen here) still carry the resonant names Zeubenelgenubi (α1,2 Lib, the southern claw) and Zeubeneschamali (β Lib, the northern claw).
This celestial scorpion was sent by a jealous Artemis to kill Orion, who sitll fees the venomous insect:as Scorpius rises Orion sets, and vice-versa. However, he could not be saved even by Asclepius, the god of healing, who was later sent into the heavens as Ophiuchus, the serpent wrestler, a symbol still used by the medical profession.
The constellation bestrides one of the richest parts of the southern Milky Way and is adorned by many beautiful stars. It is rich in young stars clusters and the nebulae from which they spring. Some examples are listed below. This images was made with Scorpius close to the horizon and with an exposure made to emphasise the bright stars. Another view shows more of the Milky Way in a longer exposure.
The named stars in the constellation: (Greek alphabet)
Acrab (β1,2 Sco), Alniyat (σ Sco), Alniyat (τ Sco), Antares (α Sco), Dschubba (δ Sco), Jabbah (ν Sco), Girtab (Sargas, θ Sco), Graffias (β1 Sco), Lesath (υ Sco), Shaula (λ Sco).
Adjoining constellations: Ara, Corona Australis, Libra Lupus, Norma, Ophiuchus, Ara, Sagittarius
Related images (other sources)
AAT 11. NGC 6302, a planetary nebula
AAT 72. A dark cloud in Scorpius
AAT 104. NGC 6231, the Sco OB association
AAT 105. IC 4628, emission nebula in Scorpius
AAT 114. NGC 6242, an open cluster
AAT 121. M4, NGC 6121, globular cluster in Scorpius
UKS 4. Antares and the Rho Ophiuchi dark cloud (Scorpius/Ophiuchus)
UKS 10. NGC 6334 and NGC 6357 in the Milky Way
UKS 30. The Antares nebula
UKS 38. Star clouds and Dust in Scorpius
Milky Way & Crux | constellations, wide field | the constellations | planets & stars | binocular views
| star trails | solar eclipses | moon & lunar eclipses | comets & aurorae | Contact DMI | 0.860677 | 3.18289 |
The world, it seems, is soon to see the first picture of a black hole.
On Wednesday, astronomers across the globe will hold “six major press conferences” simultaneously to announce the first results of the Event Horizon Telescope (EHT), which was designed precisely for that purpose.
It has been a long wait.
Of all the forces or objects in the Universe that we cannot see – including dark energy and dark matter – none has frustrated human curiosity so much as the invisible maws that shred and swallow stars like so many specks of dust.
Astronomers began speculating about these omnivorous “dark stars” in the 1700s, and since then indirect evidence has slowly accumulated.
“More than 50 years ago, scientists saw that there was something very bright at the centre of our galaxy,” Paul McNamara, an astrophysicist at the European Space Agency and an expert on black holes, told AFP.
“It has a gravitational pull strong enough to make stars orbit around it very quickly — as fast as 20 years.”
To put that in perspective, our solar system takes about 230 million years to circle the centre of the Milky Way.
Eventually, astronomers speculated that these bright spots were in fact “black holes” – a term coined by American physicist John Archibald Wheeler in the mid-1960s – surrounded by a swirling band of white-hot gas and plasma.
At the inner edge of these luminous accretion disks, things abruptly go dark.
“The event horizon” – aka the point-of-no-return – “is not a physical barrier, you couldn’t stand on it,” McNamara explained.
“If you’re on the inside of it, you can’t escape because you would need infinite energy. And if you are on the other side, you can – in principle.”
A golf ball on the moon
At its centre, the mass of a black hole is compressed into a single, zero-dimensional point.
The distance between this so-called “singularity” and the event horizon is the radius, or half the width, of a black hole.
The EHT that collected the data for the first-ever image is unlike any ever devised.
“Instead of constructing a giant telescope – which would collapse under its own weight — we combined several observatories as if they were fragments of a giant mirror,” Michael Bremer, an astronomer at the Institute for Millimetric Radio Astronomy in Grenoble, told AFP.
In April 2017, eight such radio telescopes scattered across the globe – in Hawaii, Arizona, Spain, Mexico, Chile, and the South Pole – were trained on two black holes in very different corners of the Universe to collect data.
Studies that could be unveiled next week are likely to zoom in on one or the other.
Oddsmakers favour Sagittarius A*, the black hole at the centre of our own elliptical galaxy that first caught the eye of astronomers.
Sag A* has four million times the mass of our sun, which means that the black hole is generates is about 44 million kilometres across.
That may sound like a big target, but for the telescope array on Earth some 26,000 light-years (or 245 trillion kilometres) away, it’s like trying to photograph a golf ball on the Moon.
The other candidate is a monster black hole – 1,500 times more massive even than Sag A* – in an elliptical galaxy known as M87.
It’s also a lot farther from Earth, but distance and size balance out, making it roughly as easy (or difficult) to pinpoint.
One reason this dark horse might be the one revealed next week is light smog within the Milky Way.
“We are sitting in the plain of our galaxy – you have to look through all the stars and dust to get to the centre,” said McNamara.
The data collected by the far-flung telescope array still had to be collected and collated.
“The imaging algorithms we developed fill the gaps of data we are missing in order to reconstruct a picture of a black hole,” the team said on their website.
Astrophysicists not involved in the project, including McNamara, are eagerly – perhaps anxiously – waiting to see if the findings challenge Einstein’s theory of general relativity, which has never been tested on this scale.
Breakthrough observations in 2015 that earned the scientists involved a Nobel Prize used gravitational wave detectors to track two black holes smashing together.
As they merged, ripples in the curvatures of time-space creating a unique, and detectable, signature.
“Einstein’s theory of general relativity says that this is exactly what should happen,” said McNamara.
But those were tiny black holes – only 60 times more massive than the Sun – compared to either of the ones under the gaze of the EHT.
“Maybe the ones that are millions of times more massive are different – we just don’t know yet.” | 0.897243 | 3.83212 |
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A catalog of detailed infrared portraits of more than 200 galaxies will be released publicly for the first time later this year, giving people access to exciting views of the cosmos.
The pictures were made from data collected by NASA's Spitzer Space Telescope, which is designed to study objects in the universe in infrared light. Some of the images that will be included in the new directory will be unveiled at the U.K.-Germany National Astronomy Meeting, which is being held this week in Manchester, England.
George Bendo, an astronomer at the Jodrell Bank Center for Astrophysics, will present the images at the meeting, where 900 astronomers and space scientists are gathering at the Unviersity of Manchester.
"These data show the intimate connection between the interstellar dust in galaxies, here seen shining in infrared light, and the formation of stars on a grand scale," Bendo said in a statement. "Now anyone with Internet access can download these extraordinary pictures for themselves and take a look at some of the objects being studied by the world's leading astronomers, as part of their effort to better understand the universe we live in."
The reprocessed images show nearby galaxies that were seen by the Spitzer Space Telescope between 2003 and 2009 in mid-infrared wavelengths. [Infrared Views from NASA's Spitzer Space Telescope]
Several galaxies, including M60, M61, M88 and M91, are located between 47 million and 63 million light-years away in the large cluster of galaxies in the direction of the constellation of Virgo.
The mid-infrared light from these galaxies mostly traces interstellar dust heated by hot, young stars found in regions of dynamic star formation. The image of M91 shows a prototype example of a spiral galaxy with a central bar. Although the spiral arms are easily seen in mid-infrared light, the bar is only faintly visible.
Still, the images presented by Bendo at the astronomy meeting represent only a small sample of those that will be released later in the year.
"The 24-160 micron Spitzer images need expert processing to be suitable for scientists, let alone the general public and until now many of them had been overlooked," Bendo said. "I volunteered to do this work for these galaxies as they will soon be observed by the Herschel Space Observatory at far-infrared wavelengths. With processed Spitzer data, astronomers will be able to make a direct comparison between the views from each telescope." | 0.900944 | 3.644833 |
All eyes are on Europa right now, with a dedicated NASA mission headed there in 2022, and the European Space Agency launching a more general Jupiter moon probe that will have a couple encounters with Europa that same year.
But if these orbiters are the first step toward more widespread exploration of the ocean moon, they may reveal a giant complication. Like 50 foot spikes of ice jutting out from the crust of the moon.
A paper published today in Nature Geoscience outlines this problem. Daniel Hobley of Cardiff University and his team investigated how interactions with the ocean below might affect the ice shell surrounding the moon. Europa is of special interest because of this vast ocean which makes it one of the best places to find life beyond Earth given how life here started deep in the oceans.
Hobley and his team looked toward another place with a deep ice shell and liquid water below: Antarctica. Specifically, they looked at the formation of penitentes. These structures begin their formation below, jutting out areas of higher altitude into the ice shell.
In turn, sublimation—the process of turning a solid directly into a gas—leaves behind some more compacted areas, that appear as spikes of ice, some of them taller than a human and sharp as a blade. Because the surface of Europa is ever-changing, geologically speaking, Hobley thinks there may be different kinds of spikes at different latitudes. Some of them could even reach as tall as 50 feet high.
"The surface is patchy, and some areas are clearly younger than others from the way they overlap," he says. "So, although we say the average age of the surface is 50 million years and do our calculations with that number, the younger bits of the surface would have smaller spikes, and the older parts, bigger."
But here's the bad news: They predict some of the largest spikes would exist at the equator. For several reasons, this is seen as the most ideal landing spot, as changing orbital inclination can be fuel intensive. (It's easier to get a spacecraft in a relatively straight line going across the equator than it is to get it in an orbit that's a few dozen degrees above or below that.) There could, depending on power source, also be problems with the amount of radiation a lander receives at varying latitudes.
"I guess some creative engineer could also come up with a design for a lander that would be able to land among spikes," Hobley says. "The important thing is knowing they’re there ahead of time, so NASA can plan around it."
There are some caveats here. Europa is under-explored. Hubble isn't able to make observations of structures that small with its resolution, and the last craft to explore Jupiter's moons—the Galileo craft, which took several swoops through the system from 1995 to 2003—failed to deploy the antenna that could have sent back more high resolution data. It also never got close enough to get any imaging from the low gain antenna that slowly sent back pictures taken by the mission.
This means that there isn't proof positive these structures are there. Instead, it's simply likely, based on modeling. There's thermal data from Galileo which shows heating consistent with formation of the ice spikes, and radar data hints at a jagged equatorial surface. It will take the Clipper mission to truly confirm them, with the potential problem that some versions of the mission call for a small lander.
"The most obvious thing to do would simply land away from the equator, where all the penitentes are," Hobley says. But that could require a bit more work. Maybe, in the end, we'll find a smoother patch of ground to land on there once we have enough Clipper data—but maybe we should hold off on sending a lander there immediately, lest it simply impales itself on the way down. | 0.834056 | 3.867078 |
Computed intensity of vortex coronagraph for a single point-like source. Image credit: Grover Swartzlander. Click to enlarge
“Some people say that I study darkness, not optics,” jokes Grover Swartzlander.
But it’s a kind of darkness that will allow astronomers to see the light.
Swartzlander, an associate professor in The University of Arizona College of Optical Sciences, is developing devices that block out dazzling starlight, allowing astronomers to study planets in nearby solar systems.
The devices also may prove valuable to optical microscopy and be used to protect camera and imaging systems from glare.
The core of this technology is an “optical vortex mask” – a thin, tiny, transparent glass chip that is etched with a series of steps in a pattern similar to a spiral staircase.
When light hits the mask dead on, it slows down more in the thicker layers than in thinner ones. Eventually, the light is split and phase shifted so some waves are 180 degrees out of phase with others. The light spins through the mask like wind in a hurricane. When it reaches the “eye” of this optical twister, light waves that are 180 degrees out of phase cancel one another, leaving a totally dark central core.
Swartzlander says this is like light following the threads of a bolt. The pitch of the optical “bolt” – the distance between two adjacent threads – is critical. “We’re creating something special where the pitch should correspond to a change in the phase of one wavelength of light,” he explained. “What we want is a mask that essentially cuts this plane, or sheet, of incoming light and curls it up into a continuous helical beam.”
“What we’ve found recently is knock-your-socks-off amazing from a theoretical point of view,” he added.
“Mathematically, it’s beautiful.”
Optical vortices are not a new idea, Swartzlander noted. But it wasn’t until the mid 1990s that scientists were able to study the physics behind it. That’s when advances in computer-generated holograms and high-precision lithography made such research possible.
Swartzlander and his graduate students, Gregory Foo and David Palacios, garnered media attention recently when “Optics Letters” published their article on how optical vortex masks might be used on powerful telescopes. The masks could be used to block starlight and allow astronomers to directly detect light from a 10-billion-times-dimmer planet orbiting the star.
This could be done with an “optical vortex coronagraph.” In a traditional coronagraph, an opaque disk is used to block a star’s light. But astronomers who are searching for faint planets near bright stars can’t use the traditional coronagraph because glare from starlight diffracts around the disk obscuring light reflected from the planet.
“Any small amount of diffracted light from the star is still going to overwhelm the signal from the planet,” Swartzlander explained. “But if the spiral of the vortex mask coincides exactly with the center of the star, the mask creates a black hole where there is no scattered light, and you’d see any planet off to the side.”
The UA team, which also included Eric Christensen from UA’s Lunar and Planetary Lab, demonstrated a prototype optical vortex coronagraph on Steward Observatory’s 60-inch Mount Lemmon telescope two years ago. They couldn’t search for planets outside our solar system because the 60-inch telescope isn’t equipped with adaptive optics that corrects for atmospheric turbulence.
Instead, the team took pictures of Saturn and its rings to demonstrate how easily such a mask could be used with a telescope’s existing camera system. A photo from the test is online at Swartzlander’s website, http://www.u.arizona.edu/~grovers.
Optical vortex coronagraphs could be valuable to future space telescopes, such as NASA’s Terrestrial Planet Finder (TPF) and the European Space Agency’s Darwin mission, Swartzlander noted. The TPF mission will use space-based telescopes to measure the size, temperature, and placement of planets as small as the Earth in the habitable areas of distant solar systems.
“We’re applying for grants to make a better mask – to really ramp this thing up to get better quality optics, Swartzlander said. “We can demonstrate this now in the lab for laser beams, but we need a really good-quality mask to get closer to what’s needed for a telescope.”
The big challenge is developing a way to etch the mask to get “a big fat zero of light” at its core, he said.
Swartzlander and his graduate students are doing numerical simulations to determine the proper pitch for helical masks at the desired optical wavelengths. Swartzlander has filed a patent for a mask that covers more than one wavelength, or color of light.
The U.S. Army Research Office and State of Arizona Proposition 301 funds support this research.
The Army Research Office funds basic optical sciences research, although Swartzlander’s work also has practical defense applications.
Optical vortex masks also could be used in microscopy to enhance the contrast between biological tissues.
Original Source: UA News Release | 0.851218 | 3.713474 |
The European Space Agency’s Venus Express orbiter observed heat patterns on the slopes of a Venusian volcano that indicated relatively recent lava flows. But “relatively recent” in this case, based on data from the spacecraft’s Infrared and Visible Thermal Imaging Spectrometer, meant anytime between now and 2.5 million years ago.
New research, based on a laboratory analysis, indicates eruptions may, in fact, be happening today, making Venus the only other planet in the solar system with truly recent volcanism.
“If Venus is indeed active today, it would make a great place to visit to better understand the interiors of planets,” said Justin Filiberto, the study’s lead author and a Universities Space Research Association (USRA) staff scientist at the Lunar and Planetary Institute. “For example, we could study how planets cool and why the Earth and Venus have active volcanism, but Mars does not. Future missions should be able to see these flows and changes in the surface and provide concrete evidence of its activity.”
The Venus Express data allowed scientists to recognise fresh versus altered flows of lava on Venus’ surface. Filiberto and his colleagues recreated the planet’s hot, caustic atmosphere in the laboratory and monitored how olivine, an abundant basaltic mineral, reacted.
As it turned out, the olivine reacted, or “weathered,” very rapidly, becoming coated with iron oxide minerals within a few weeks.
“Our results suggest that these high-emissivity lava flows are not millions or even thousands of years old but were emplaced at most a few years before detection,” the team’s paper concludes. “If so, then Venus is volcanically active today because our experimental results show that the emissivity/reflectance signature of olivine should be obscured by oxide coatings within months to years.
“This active volcanism is consistent with episodic spikes of sulphur dioxide in the atmosphere measured by both the Pioneer Venus Orbiter and the Venus Express, which could have been produced by the same eruption that formed the young lava flows” observed by the Venus Express spacecraft. | 0.862666 | 3.921785 |
The Nobel Prizes in Science are among the most significant awards one can receive. Three scientists have been awarded the Nobel Prize in Physics for their work in unraveling what the universe is made of, and for being the first to discover an exoplanet.
Canadian scientist James Peebles and Swiss astronomers Michel Mayor and Didier Queloz are splitting the 9 million Swedish krona ($906,705) Nobel Prize money for their separate discoveries, according to a press release on Tuesday, October 8.
Peebles’ work includes his findings on the evolution of the universe and the clues microwave radiation has left behind.
“I could think of one or two things to do in cosmology. I just did them and kept going,” Peebles said to the Royal Swedish Academy of Sciences on Tuesday. “The prizes and awards, they are charming, much appreciated, but that’s not part of your plans. You should enter science because you are fascinated by it.”
He is also credited with the development of tools that have allowed other scientists to explore further what the universe is made from, which is a combination of ordinary matter, dark matter, and dark energy.
Dark matter and dark energy are two of the biggest mysteries in astronomy. Dark energy is a force theorized to exist to explain the movements of distant galaxies. Because of Peeble’s work, we now know that about 68% of the universe is made of dark energy.
Mayor and Queloz are credited with discovering the first exoplanet back in 1995. The exoplanet, known as 51 Pegasi b, is 50 light-years away in the Pegasus constellation and is 150 times bigger than Earth, with a surface temperature of 1,000 degrees Celsius (1,832 degrees Fahrenheit).
Their discovery of the first exoplanet has allowed astronomers to find and identify not only other exoplanets, but also “Super-Earths,” or planets that have the potential to support life. NASA has confirmed the existence of more than 4,000 planets outside our solar system. The sheer number of that is impressive, but even more so if you take into consideration that, before Mayor and Queloz, we couldn’t find any exoplanets.
Other Nobel Prizes to be given out this week include the Nobel Prize for Chemistry, the Nobel Prize for Literature, and the Nobel Peace Prize.
- NASA renames planet-finding telescope after woman trailblazer
- Astronomers have found the universe’s ‘missing matter’ thanks to cosmic bursts
- Hubble solves the mystery of the bizarre disappearing exoplanet
- Hubble spots a wacky exoplanet with yellow skies and iron rain
- New Earth-sized planet discovered 300 light-years away could support life | 0.872946 | 3.110296 |
In 2006, Pluto ceased to be a planet. It was degraded by the International Astronomical Union to dwarf planet. But an asteroid called Ceres was "promoted." Did it help us learn more about the solar system?
Talk about being on the outer. Pluto. It was the last planet to be discovered and only because it was thought a ninth planet had to exist to explain some odd happenings around Uranus and Neptune. That was in 1930. And Clyde Tombaugh was the lucky astronomer.
It turns out Tombaugh was very lucky, indeed. Those odd happenings only appeared to be odd because scientists had yet to determine the correct mass of Neptune. But he was looking in the right spot and found Pluto. And it was more or less assumed Pluto had to be a planet because no other objects were known to exist at that distance from the sun.
But people did often wonder about its planetary status. Then about 60 years later, with the discovery of the Kuiper belt, things started to go pear-shaped for poor old Pluto.
"In 1992, when a second object was observed at [a similar] distance, and then many more, Pluto was no longer seen as something special that made it a planet," says Dr. Hermann Böhnhardt at the Max Planck Institute for Solar System Research.
The discovery of the Kuiper belt really was the death knell for Planet Pluto. The Kuiper belt is home to thousands of objects, and some are larger than Pluto.
"There were a number of objects observed to be the same size as Pluto and that resulted in this discussion about whether Pluto can be a planet or not, and if it's the ninth one do we keep counting to 100?!" says Dr Ralf Jaumann at the Institute for Planetary Research at the German Aerospace Center. "So we needed to really think about what makes a planet and what is a dwarf planet."
Out of that came a decision from the International Astronomical Union (IAU) to degrade Pluto to the status of dwarf planet. Pluto was just narrowly spared an ignominious fate as an asteroid - no offense intended, of course, to any asteroids, some of whom moved up the greasy pole.
"Ceres [once an asteroid] and Eris, another object in the Kuiper belt beyond Pluto, fulfilled the criteria and were, if you will, promoted," says Böhnhardt. "But from a scientific point of view - for me and many colleagues - this reclassification made no difference, because Pluto was no longer considered a planet since the discovery of the Kuiper belt."
Essentially, though, the IAU's criteria for dwarf planets says the shape of the object is dominated by hydrostatic forces, making them "nearly round."
So what was the point?
These small objects may be small but they loom large in the evolution of our solar system. They are described as "primitive" objects because they have undergone the least change - for instance through collisions with other objects - since the formation of the planetary system. And because planets essentially consist of such small objects, and the materials that derive from them, small objects can tell us a lot about the larger planets, such as Earth.
And what is there to learn about Earth? Well, for one, we don't even know where all the water came from.
So did Pluto's reclassification as a dwarf planet - a small object - redirect science priorities and inspire new research in this area? Not quite.
"There is more research in this area but not as a result of Pluto's reclassification," says Jaumann. "There is more research because we have better telescopes now and better spacecraft for investigating smaller bodies."
An old dawn
One such spacecraft is Dawn. The Dawn mission is headed by NASA. It is currently investigating Ceres, and before that it visited Vesta, an asteroid.
Researchers hope Dawn will let them pop back to the first few millions of years after the planets were formed. The most recent data about Ceres' gravity has even allowed them to look inside the dwarf planet.
However, the mission was not spawned by the new dwarf planets. Although it had been canceled and reinstated a few times, Dawn was first up for consideration in 2001.
"So it was not triggered by the renaming of Pluto. The trigger was we are able to do it now," says Jaumann.
Similarly, the New Horizons mission to Pluto launched in January 2006 - eight months before the IAU's decision to reclassify the small object.
Its encounter with Pluto ended in January of this year. But it's not over yet. There are still hoards of New Horizons data to sift through. And let's not forget, Pluto is in the Kuiper belt, an area vastly unknown.
Scientists say there could be several hundred thousand objects bigger than 30 kilometers (20 miles) across, and we have yet to find them, these primitive things from the beginnings of our planetary system. There will be future missions.
You have a "spectrum of bodies" in our planetary system from "small dust grains to gravel-sized objects," says Böhnhardt, and then you have these small objects of a few meters, kilometers or a few thousand kilometers, and a few number of planets.
"But they are the outcome of the same process and that's how I see them," he says.
"We've visited all the planets with space missions now, and you can get a first glimpse of planetary properties around other stars from Earth-based observations, so [probing small objects] will hopefully give us a complete picture of how things are and how things have evolved. But we're not there yet, we still can't explain planetary formation," says Böhnhardt.
So then what of the tenth anniversary of the IAU's degrading of Pluto, and classification of dwarf planets? Was it any use?
"It's been useful," says Böhnhardt, "and it is used a lot. The classification of the dwarf planet is less specific than the one for a planet, so the IAU could have given this a bit more emphasis, but it is like it is for the moment." | 0.903387 | 3.668559 |
DOE Approves Construction of 3-D Galaxy-mapping Project ‘DESI’
DOE Approves Construction of 3-D Galaxy-mapping Project ‘DESI’
A 3-D sky-mapping project that will measure the light of 35 million cosmic objects has received formal approval from the Department of Energy to move forward with construction. Installation of the project, called Dark Energy Spectroscopic Instrument (DESI), is set to begin next year at the Mayall 4-meter telescope at Kitt Peak National Observatory near Tucson, Arizona, with observations starting up in January 2019.
Researchers from DOE’s SLAC National Accelerator Laboratory are part of the DESI collaboration, which includes about 300 scientists and engineers from about 45 institutions around the globe.
“We’re very excited – ecstatic – that we’ve gotten to this step,” said DESI Director Michael Levi of Lawrence Berkeley National Laboratory’s Physics Division.
The approval step, known as Critical Decision 3, triggers spending for major components of the project, including the rest of the 5,000 robots that will precisely point the instrument’s fiber-optic cables to gather the light from a chosen set of galaxies, stars and brilliant objects called quasars. The spending will also be used to complete the set of 10 fiber-fed spectrographs that will precisely measure different wavelengths of incoming light.
The first “petal” machined for the Dark Energy Spectroscopic Instrument (DESI) is shown in these photos. Ten of these petals will hold 5,000 robots (like the one in the lower right photo), each pointing a thin fiber-optic cable at separate sky objects. (J. Silber/Berkeley Lab)
This light will tell us about the properties of cosmic objects. Since light from objects moving away from us is shifted to redder wavelengths – a phenomenon known as redshift – it will also reveal how quickly the objects are moving away. These details can help us learn more about the nature of dark energy, an unknown form of energy that is driving the accelerating expansion of the universe. DESI’s observations will provide a deep look back in time, up to about 11 billion years ago.
“DESI will be able to make a 3-D map of the universe using an order of magnitude more redshifts than currently exist,” said DESI co-spokesperson Risa Wechsler of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC). “This will allow us to probe the physics of the universe and discover the true nature of dark energy." KIPAC is a joint institute of Stanford University and SLAC.
Studying Cosmic Expansion History
DESI's robotic array will cycle through separate sets of objects several times each hour during its five-year mission. It will look at one-third of the sky and capture more than 10 times as much data as a predecessor, the Baryon Oscillation Spectroscopic Survey (BOSS).
DESI will provide a more detailed look at the patterned clustering of visible matter in the night sky across a larger range of distances. DESI will also provide a more precise measure of how the universe has spread out over time and help us understand galaxy evolution and dark matter, which is invisible but inferred from its gravitational effects on normal matter.
"The DESI map of galaxies will reveal patterns that result from the interplay of pressure and gravity in the first 400,000 years after the Big Bang," said DESI co-spokesperson Daniel Eisenstein of Harvard University. "We'll be using these subtle fingerprints to study the expansion history of the universe."
Three sky surveys, including the Dark Energy Survey (DES), are now collecting images of the faint galaxies that DESI will target.
“I like to think of the imaging surveys as building the 2-D maps, while DESI adds the third dimension,” said Dustin Lang, a DESI imaging scientist with the University of Toronto. “The crucial third dimension allows us to measure how galaxies cluster together in space over the history of the universe.”
The Dark Energy Spectroscopic Instrument (DESI) will measure the light from 35 million galaxies, stars and quasars, resulting in the largest 3-D map of the universe ever constructed. The instrument will be mounted on the 4-meter Mayall telescope at Kitt Peak National Observatory. (R. Lafever/J. Moustakas/DESI Collaboration)
Moving Toward Project Completion
With the latest approval, a pipeline of development efforts will move quickly toward completion.
Six large lenses, each worth $1 million and measuring up to 1.1 meters in diameter, await treatment with an antireflective coating to improve their transparency. The lenses will be housed in a metal frame being constructed at Fermi National Accelerator Laboratory to form a minivan-sized stack known as an optical corrector. This device will be the first piece of equipment installed at the Mayall telescope for DESI in 2018.
To prepare for DESI data analysis, software engineers are using supercomputers at Berkeley Lab’s National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility, to simulate the data that DESI will gather.
A prototype instrument called ProtoDESI is now installed at the telescope for a two-month run. It uses four small robots to test out the fiber-positioning system and includes cameras and other components to prepare for the full DESI project.
SLAC scientists are involved in various aspects of the project. Kevin Reil and Aaron Roodman are contributing to the system that will guide DESI’s cameras and make sure they are properly focused and aligned. Eli Rykoff is developing software tools to validate data from ongoing imaging surveys that will help select observation targets for DESI. In addition to her leadership of the DESI collaboration, Wechsler is working on computer simulations that will turn DESI’s redshifts into a better picture of cosmic structure and evolution.
A view of the ProtoDESI setup during assembly at Berkeley Lab, with the underside of the robotic fiber positioners at left. ProtoDESI is now installed at the 4-meter Mayall Telescope at Kitt Peak National Observatory. (P. Mueller/Berkeley Lab)
A New Generation of Surveys
DESI is one of several planned next-generation observatory projects designed to confront cosmic mysteries, such as dark energy and dark matter. Its data will complement, for instance, information from the future Large Synoptic Survey Telescope (LSST), which will begin in 2022 to take images of billions of objects in never-before-seen detail. SLAC is leading the construction of LSST’s 3.2-gigapixel camera, the largest digital camera ever built for ground-based optical astronomy.
“DESI’s spectroscopic survey will give us different pieces of information than LSST’s imaging survey,” Wechsler said. “By putting the pieces together, we’ll be able to draw a more complete, more accurate picture of what the universe is doing.”
DESI is supported by the DOE Office of Science. Additional support is provided by the National Science Foundation, Division of Astronomical Sciences under contract to the National Optical Astronomy Observatory; the Science and Technology Facilities Council of the United Kingdom; the Gordon and Betty Moore Foundation; the Heising-Simons Foundation; the National Council of Science and Technology of Mexico; the Ministry of Economy and Competitiveness of Spain; and DESI member institutions. The DESI scientists are honored to be permitted to conduct astronomical research on Iolkam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O’odham Nation.
Editor’s note: This feature is based on a Berkeley Lab press release.
For questions or comments, contact the SLAC Office of Communications at [email protected].
SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, Calif., SLAC is operated by Stanford University for the U.S. Department of Energy's Office of Science.
SLAC National Accelerator Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov. | 0.885158 | 3.409243 |
eso1817 — Science Release
ALMA and VLT Find Too Many Massive Stars in Starburst Galaxies, Near and Far
4 June 2018
Astronomers using ALMA and the VLT have discovered that both starburst galaxies in the early Universe and a star-forming region in a nearby galaxy contain a much higher proportion of massive stars than is found in more peaceful galaxies. These findings challenge current ideas about how galaxies evolved, changing our understanding of cosmic star-formation history and the build up of chemical elements.
Probing the distant Universe a team of scientists, led by University of Edinburgh astronomer Zhi-Yu Zhang, used the Atacama Large Millimeter/submillimeter Array (ALMA) to investigate the proportion of massive stars in four distant gas-rich starburst galaxies . These galaxies are seen when the Universe was much younger than it is now so the infant galaxies are unlikely to have undergone many previous episodes of star formation, which might otherwise have confused the results.
Zhang and his team developed a new technique — analogous to radiocarbon dating (also known as carbon-14 dating) — to measure the abundances of different types of carbon monoxide in four very distant, dust-shrouded starburst galaxies . They observed the ratio of two types of carbon monoxide containing different isotopes .
“Carbon and oxygen isotopes have different origins”, explains Zhang. “18O is produced more in massive stars, and 13C is produced more in low- to intermediate-mass stars.” Thanks to the new technique the team was able to peer through the dust in these galaxies and assess for the first time the masses of their stars.
The mass of a star is the most important factor determining how it will evolve. Massive stars shine brilliantly and have short lives and less massive ones, such as the Sun, shine more modestly for billions of years. Knowing the proportions of stars of different masses that are formed in galaxies therefore underpins astronomers’ understanding of the formation and evolution of galaxies throughout the history of the Universe. Consequently, it gives us crucial insights about the chemical elements available to form new stars and planets and, ultimately, the number of seed black holes that may coalesce to form the supermassive black holes that we see in the centres of many galaxies.
Co-author Donatella Romano from the INAF-Astrophysics and Space Science Observatory in Bologna explains what the team found: “The ratio of 18O to 13C was about 10 times higher in these starburst galaxies in the early Universe than it is in galaxies such as the Milky Way, meaning that there is a much higher proportion of massive stars within these starburst galaxies.”
The ALMA finding is consistent with another discovery in the local Universe. A team led by Fabian Schneider of the University of Oxford, UK, made spectroscopic measurements with ESO’s Very Large Telescope of 800 stars in the gigantic star-forming region 30 Doradus in the Large Magellanic Cloud in order to investigate the overall distribution of stellar ages and initial masses .
Schneider explained, “We found around 30% more stars with masses more than 30 times that of the Sun than expected, and about 70% more than expected above 60 solar masses. Our results challenge the previously predicted 150 solar mass limit for the maximum birth mass of stars and even suggest that stars could have birth masses up to 300 solar masses!”
Rob Ivison, co-author of the new ALMA paper, concludes: “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.”
Starburst galaxies are galaxies that are undergoing an episode of very intense star formation. The rate at which they form new stars can be 100 times or more the rate in our own galaxy, the Milky Way. Massive stars in these galaxies produce ionising radiation, stellar outflows, and supernova explosions, which significantly influence the dynamical and chemical evolution of the medium around them. Studying the mass distribution of stars in these galaxies can tell us more about their own evolution, and also the evolution of the Universe more generally.
The radiocarbon dating method is used for determining the age of an object containing organic material. By measuring the amount of 14C, which is a radioactive isotope whose abundance continuously decreases, one can calculate when the animal or plant died. The isotopes used in the ALMA study, 13C and 18O, are stable and their abundances continuously increase during the lifetime of a galaxy, being synthesised by thermal nuclear fusion reactions inside stars.
These different forms of the molecule are called isotopologues and they differ in the number of neutrons they can have. The carbon monoxide molecules used in this study are an example of such molecular species, because a stable carbon isotope can have either 12 or 13 nucleons in its nucleus, and a stable oxygen isotope can have either 16, 17, or 18 nucleons.
Schneider et al. made spectroscopic observations of individual stars in 30 Doradus, a star-forming region in the nearby Large Magellanic Cloud, using the Fibre Large Array Multi Element Spectrograph (FLAMES) on the Very Large Telescope (VLT). This study was one of the first to be carried out that has been detailed enough to show that the Universe is able to produce star-forming regions with different mass distributions from that in the Milky Way.
The ALMA results are published in a paper entitled “Stellar populations dominated by massive stars in dusty starburst galaxies across cosmic time” that will appear in Nature on 4 June 2018. The VLT results are published in a paper entitled “An excess of massive stars in the local 30 Doradus starburst”, which has been published in Science on 5 January 2018.
The ALMA team is composed of: Z. Zhang (Institute for Astronomy, University of Edinburgh, Edinburgh, UK; European Southern Observatory, Garching bei München, Germany), D. Romano (INAF, Astrophysics and Space Science Observatory, Bologna, Italy), R. J. Ivison (European Southern Observatory, Garching bei München, Germany; Institute for Astronomy, University of Edinburgh, Edinburgh, UK), P .P. Papadopoulos (Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece; Research Center for Astronomy, Academy of Athens, Athens, Greece;) and F. Matteucci (Trieste University; INAF, Osservatorio Astronomico di Trieste; INFN, Sezione di Trieste, Trieste, Italy)
The VLT team is composed of: F. R. N. Schneider ( Department of Physics, University of Oxford, UK), H. Sana (Institute of Astrophysics, KU Leuven, Belgium), C. J. Evans ( UK Astronomy Technology Centre, Royal Observatory Edinburgh, Edinburgh, UK), J. M. Bestenlehner (Max-Planck-Institut für Astronomie, Heidelberg, Germany; Department of Physics and Astronomy, University of Sheffield, UK), N. Castro (Department of Astronomy, University of Michigan, USA), L. Fossati (Austrian Academy of Sciences, Space Research Institute, Graz, Austria), G. Gräfener (Argelander-Institut für Astronomie der Universität Bonn, Germany), N. Langer (Argelander-Institut für Astronomie der Universität Bonn, Germany), O. H. Ramírez-Agudelo (UK Astronomy Technology Centre, Royal Observatory Edinburgh, Edinburgh, UK), C. Sabín-Sanjulián (Departamento de Física y Astronomía, Universidad de La Serena, Chile), S. Simón-Díaz (Instituto de Astrofísica de Canarias, Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain), F. Tramper (European Space Astronomy Centre, Madrid, Spain), P. A. Crowther (Department of Physics and Astronomy, University of Sheffield, UK), A. de Koter (Astronomical Institute Anton Pannekoek, Amsterdam University, Netherlands; Institute of Astrophysics, KU Leuven, Belgium), S. E. de Mink (Astronomical Institute Anton Pannekoek, Amsterdam University, Netherlands), P. L. Dufton (Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Northern Ireland, UK), M. Garcia (Centro de Astrobiología, CSIC-INTA, Madrid, Spain), M. Gieles (Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, UK), V. Hénault-Brunet (National Research Council, Herzberg Astronomy and Astrophysics, Canada; Department of Astrophysics/Institute for Mathematics, Astrophysics and Particle Physics, Radboud University, Netherlands), A. Herrero (Departamento de Física y Astronomía, Universidad de La Serena, Chile), R. G. Izzard (Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, UK; Institute of Astronomy, The Observatories, Cambridge, UK), V. Kalari (Departamento de Astronomía, Universidad de Chile, Santiago, Chile), D. J. Lennon (European Space Astronomy Centre, Madrid, Spain), J. Maíz Apellániz (Centro de Astrobiología, CSIC–INTA, European Space Astronomy Centre campus, Villanueva de la Cañada, Spain), N. Markova (Institute of Astronomy with National Astronomical Observatory, Bulgarian Academy of Sciences, Smolyan, Bulgaria), F. Najarro (Centro de Astrobiología, CSIC-INTA, Madrid, Spain), Ph. Podsiadlowski (Department of Physics, University of Oxford, UK; Argelander-Institut für Astronomie der Universität Bonn, Germany), J. Puls (Ludwig-Maximilians-Universität München, Germany), W. D. Taylor (UK Astronomy Technology Centre, Royal Observatory Edinburgh, Edinburgh, UK), J. Th. van Loon (Lennard-Jones Laboratories, Keele University, Staffordshire, UK), J. S. Vink (Armagh Observatory, Northern Ireland, UK) and C. Norman (Johns Hopkins University, Baltimore, USA; Space Telescope Science Institute, Baltimore, USA)
ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It has 15 Member States: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and with Australia as a strategic partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.
University of Edinburgh and ESO
Garching bei München, Germany
Department of Physics — University of Oxford
Oxford, United Kingdom
Garching bei München, Germany
ESO Outreach Astronomer
Garching bei München, Germany
Tel: +49 89 3200 6188 | 0.846819 | 4.009776 |
Saturn is now being recognized as the “moon king” of our solar system, with astronomers spotting 20 more of them orbiting the giant ringed planet, bringing its total count to 82—three more than Jupiter.
The newly identified small moons, ranging from about 2 to 4 miles (3 to 6 km) in diameter, were detected using the Subaru telescope in Hawaii by a research team led by astronomer Scott Sheppard of the Carnegie Institution for Science in Washington.
“Saturn is the moon king,” Sheppard said on Oct. 9 in an email interview.
The discovery was announced this week by the International Astronomical Unions Minor Planet Center.
One of the moons orbits at an astounding distance of about 15 million miles (24 million km) from Saturn, farther away than any of its other moons. By comparison, Earths moon orbits about 240,000 miles (386,000 km) from the planet.
Seventeen of the newly detected Saturnian moons are orbiting in the opposite direction of the planets rotation. The other three orbit in the same direction Saturn spins, as is typically the case.
A number of the moons appear to be fragments of once-larger moons that broke up in long-ago collisions with other moons or passing comets or asteroids, Sheppard said. That is similar to some of the 79 moons orbiting Jupiter.
Saturn, a gas giant made up mostly of hydrogen and helium, is the second-largest planet in the solar system and the sixth from the sun. Its diameter of about 72,000 miles (116,000 km) dwarfs Earth diameter of about 7,900 miles (12,700 km).
Only Jupiter, the fifth planet from the sun, is larger. | 0.846062 | 3.265348 |
Marianne Dyson, September 2018
Visible in the evening starting this month, the two brightest stars of Orion are showing off their colors. But red Betelgeuse (Orion’s left shoulder, pronounced “beetle-juice”) and blue Rigel (Orion’s right foot, pronounced “rye-gel”) are destined to produce truly spectacular performances in the future.
Big and Bright
People used to think that all stars are about the same size. Therefore, stars that appeared brighter must be closer like flashlights near versus farther away.
Then in 1905, astronomer Ejnar Hertzsprung used parallax (see July blog) to measure the distance to both bright and faint stars. Surprise! Some bright stars were the same distance as dim ones, and some much farther away. The reason? Some stars are brighter because they are physically bigger, like a floodlight versus a flashlight. This was proven correct in 1920 when astronomers measured the angular diameter of Betelgeuse using the (then) new 100-inch telescope on Mount Wilson. Betelgeuse is so large that if it replaced the sun, it would stretch out past the orbit of Jupiter. [Ref: European Southern Observatory.]
Betelgeuse is Cool
Betelgeuse is very obviously a different color than most stars. Human eyes see it as orangish red whereas Rigel looks blue. These colors aren’t just pretty, they reveal the temperature of the star.
Human eyes are good at judging heat output by color. Anyone who has ever roasted a marshmallow quickly discovers that a blue flame will burn it to a crisp whereas a warm yellow fire or a set of red embers will slowly brown it. Thankfully, we don’t have to hold marshmallows up to various stars to prove some are hotter than others. Scientists have quantified the colors by wavelengths so all we have to do is look at their spectra to tell precisely how hot stars are.
Human eyes only see a portion of a star’s total spectrum, aptly named the visible spectrum. The “coolest” end of the visible spectrum is red. The “hottest” is purple also called violet. (Physics students memorize the order: Red, Orange Yellow, Green, Blue, Indigo, Violet, as the name ROY G BIV.)
So just by looking at stars we can tell which ones are the coolest! Betelgeuse is a cool red. In the middle, temperature-wise, is our yellow sun. Blue Rigel is the hottest. (See Bad Astronomy for why we don’t see green stars.)
Stellar spectra (seen via prisms or spectrometers) allow astronomers to measure the temperatures of stars. The surface of Betelgeuse is about 5800 degrees F, about half as hot as the Sun at 10,000 degrees. Rigel would vaporize our marshmallows long before we got close to its 36,000-degree surface. [Ref: Griffith Observatory.]
Why is Betelgeuse so cool?
Red in the End
The temperature of a star depends mostly on its mass and age. Stars form by gravity pulling gas into a ball until it is hot enough to start nuclear reactions. The rate of those reactions, and thus how hot the star gets, depends on how much gas ends up in the ball. Blue Rigel is 20 times more massive than our yellow sun.
But what about Betelgeuse? It’s red, so does that mean it’s smaller than the Sun? Nope. There are two kinds of red stars: “adult” main sequence stars (which are the most common of all stars), and red giants in their final days. Betelgeuse has almost as much mass as Rigel. It is red because it is dying.
As stars use up their hydrogen fuel, the centers contract, and the outer layers expand out and cool. The stars become giant red puff balls regardless of what color they started out. In about 5 billion years, the Sun will become one of these red giants, expanding out past the orbit of Venus and toasting Earth’s marshmallow. It only took Betelgeuse about 10 million years to reach the giant, or in this case, supergiant, phase. Because of its huge mass, Rigel will become a red supergiant too, likely in the next few million years.
The red giant stage is a relatively short period of a star’s life, which is why there are so few visible in the sky. The red giant stage is followed by a final collapse of the center of the star as it runs out of fuel and can’t push back against gravity’s squeeze. For small and average stars, the collapse produces a white (hot) dwarf star about the size of Earth. Big stars like Betelgeuse and Rigel collapse violently, producing supernovas and leaving behind pulsars or black holes. Astronomers estimate that Betelgeuse’s supernova will outshine a full Moon when it happens: which could be tomorrow or a million years from now.
So while enjoying the colorful “preview” show of Orion this fall, have fun thinking about how this constellation will look when Betelgeuse “moons” the sky and Rigel blushes red!
Writing about Space
An excerpt of my memoir, A Passion for Space, describing my experiences as a flight controller during the first space shuttle launch, will be included in the FenCon 2018 Program Book this September. Attend to get your copy!
My next book, coauthored with Buzz Aldrin, To the Moon and Back: My Apollo 11 Adventure, a pop-up book from National Geographic with art by Bruce Foster, is available for preorder now from Amazon. Look for it in stores everywhere on October 16.
My science fact article, “In Defense of the Planet,” is in the Nov/Dec 2018 issue of Analog. Get your subscription now!
Speaking about Space
September 21-23, Science GOH at FenCon XV in Dallas. Writer GOH is Larry Niven. Tickets are available at the door.
September 29, Attending SCBWI Houston conference. Come and get a special pop-up book mark for To the Moon and Back designed by artist Bruce Foster.
October 2, Instructor for first class of Women and Space course at Rice University’s Glasscock School of Continuing Studies.
October 12, Featured speaker on Friday 11 to noon at the National Science Teachers Association conference in Reno, Nevada.
See my contact page for a complete appearance schedule and photos from previous events. | 0.891942 | 3.81734 |
Dozens of binaries from Milky Way's globular clusters could be detectable by LISA
Next-generation gravitational wave detector in space will complement LIGO on Earth
EVANSTON, Ill. --- The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A string of detections -- four more binary black holes and a pair of neutron stars -- soon followed the Sept. 14, 2015, observation.
Now, another detector is being built to crack this window wider open. This next-generation observatory, called LISA, is expected to be in space in 2034, and it will be sensitive to gravitational waves of a lower frequency than those detected by the Earth-bound Laser Interferometer Gravitational-Wave Observatory (LIGO).
A new Northwestern University study predicts dozens of binaries (pairs of orbiting compact objects) in the globular clusters of the Milky Way will be detectable by LISA (Laser Interferometer Space Antenna). These binary sources would contain all combinations of black hole, neutron star and white dwarf components. Binaries formed from these star-dense clusters will have many different features from those binaries that formed in isolation, far from other stars.
The study is the first to use realistic globular cluster models to make detailed predictions of LISA sources. "LISA Sources in Milky-Way Globular Clusters" was published today, May 11, by the journal Physical Review Letters.
"LISA is sensitive to Milky Way systems and will expand the breadth of the gravitational wave spectrum, allowing us to explore different types of objects that aren't observable with LIGO," said Kyle Kremer, the paper's first author, a Ph.D. student in physics and astronomy in Northwestern's Weinberg College of Arts and Sciences and a member of a computational astrophysics research collaboration based in Northwestern's Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA).
In the Milky Way, 150 globular clusters have been observed so far. The Northwestern research team predicts one out of every three clusters will produce a LISA source. The study also predicts that approximately eight black hole binaries will be detectable by LISA in our neighboring galaxy of Andromeda and another 80 in nearby Virgo.
Before the first detection of gravitational waves by LIGO, as the twin detectors were being built in the United States, astrophysicists around the world worked for decades on theoretical predictions of what astrophysical phenomena LIGO would observe. That is what the Northwestern theoretical astrophysicists are doing in this new study, but this time for LISA, which is being built by the European Space Agency with contributions from NASA.
"We do our computer simulations and analysis at the same time our colleagues are bending metal and building spaceships, so that when LISA finally flies, we're all ready at the same time," said Shane L. Larson, associate director of CIERA and an author of the study. "This study is helping us understand what science is going to be contained in the LISA data."
A globular cluster is a spherical structure of hundreds of thousands to millions of stars, gravitationally bound together. The clusters are some of the oldest populations of stars in the galaxy and are efficient factories of compact object binaries.
The Northwestern research team had numerous advantages in conducting this study. Over the past two decades, Frederic A. Rasio and his group have developed a powerful computational tool -- one of the best in the world -- to realistically model globular clusters. Rasio, the Joseph Cummings Professor in Northwestern's department of physics and astronomy, is the senior author of the study.
The researchers used more than a hundred fully evolved globular cluster models with properties similar to those of the observed globular clusters in the Milky Way. The models, which were all created at CIERA, were run on Quest, Northwestern's supercomputer cluster. This powerful resource can evolve the full 12 billion years of a globular cluster's life in a matter of days. | 0.86052 | 3.875154 |
Exoplanet – a planet which orbits a star outside the solar system
Prior to 1992 not a single exoplanet was known to exist. Now, here we sit 24 years later having discovered 3,537 exoplanets in 2,653 planetary systems. The field of exoplanetary science has without a doubt been the booming area of astronomy in the last decade. So it’s only right Rationalising the Universe respects this big thinking field of science and we go on a little whistle-stop tour through the history of exoplanet exploration, explain how detections are made and discover just how strange some of these new worlds are. This is a topic which has a special place in my heart (brain) as when i’m not typing away furiously on this site I work for a UK Space Mission which will, come 2019, launch a satellite into low-earth orbit to look at exoplanets which have already been discovered in our galaxy to learn more about what they are made of, what their evolution history is and ultimately to answer the question of whether they are habitable.
“This space we declare to be infinite…in it are an infinity of worlds of the same kind as our own.” Giordano Bruno (1584)
Although thoughts go back centuries it was only in 1992 that Aleksander Wolszcan and Dale Frail announced the discovery of two rocky planets orbiting PSR B1 257+12, a complicated name for a pulsar in the constellation Virgo. Then shortly after in 1995 we entered more familiar territory and found the first exoplanet orbiting around a main-sequence star. (Main-sequence stars are in hydrostatic equilibrium, where thermal pressure form the core is balanced by inward pressure of gravitational collapse.) Our sun is a main sequence star and as such this discovery was pivotal to the understanding that our solar system is not that rare or unique after all. The star was 51 Pegasi, and the planet, (roughly half the size of Jupiter) was named 51 Pegasi-b, as is the slightly bland but effective book-keeping convention of naming planets – add a letter after the star name.
Then in 1999 we got the discovery of the first multi-planetary system – excitement went up a notch in the community. Researchers from San Francisco State University published the discovery of two additional planets orbiting the star Upsilon Andromeda in the constellation Pegasus, which was already known to have one exoplanet. Planets had begun to pop up left right and center in the sky. Then the excitement was turned up another notch – 2001 the first planet found within the ‘habitable zone’! Geneva University astronomers discovered HD 28185 b, a planet that orbits its star at roughly the same distance the Earth does from the sun. The habitable zone differs depending on the size of the star, i.e. the heat it emits, it is the zone where it is not too hot yet not too cold so that an atmosphere can be maintained around a planet such that then life could possibly exist. In 2002 we got the first ‘normal’ solar system, with a Jupiter-like planet orbiting a star at similar distance to Jupiter in our solar system instead of taking an extremely close, or in colloquial terms, ‘roasting’ orbit. Then finally in 2014 we got the first Earth-sized planet in the habitable zone, where liquid water had the potential to exist on the planet’s surface – Kepler 186f.
So there we have the milestone discoveries in the field but now time to discuss how they are discovered before delving into the wacky, wonderful and downright weird different types of planets that exist.
- Radial Velocity
The first method has the record for discovery of the most exoplanets, weighing in 536 discoveries. This method is the Radial Velocity method or ‘Watching for Wobble’ as NASA likes to call it. When the planet orbits around the star its gravitational force (due to its mass) causes the star around which it travels to ‘wobble’ a little bit. When the planet is on the left of the star, the star is pulled to the left a little bit and when its on the right it is pulled to the right. Astrophysicists can detect this wobble in the wavelengths of the light they receive from the star as when the star moves to and fro the light waves compress and then stretch out, repeating this pattern in a regular manner due to the regular orbital period of the planet.
- Transit Method
The second method has produced 306 discoveries, this is the transit method or ‘Searching for Shadows’. The telescope looks at light from a far away star, then every so often the exoplanet of passes in-front of the star whilst on its orbit and blocks out a little light from the star, making it dimmer. It is this periodic dip in the brightness of the star that allows us to detect the exoplanet. Much information can be obtained from the transit method – bigger planets block out more light and the father away a planet is the longer it takes to orbit and pass in front of the star.
This method can also characterise the planets as, when comparing the wavelengths of light received from the star when the planet was and was not in front of it we can deduce what molecules are present in the planet’s atmosphere. This is because, depending on which molecules are present in the atmosphere of the planet, different wavelengths of light are absorbed from the star. With this extra information we can ask questions like what are the exoplanets made of, what the weather is like there and the ask the ultimate question – are they are habitable? If we see that key molecules such as H20 or C02 are present this would be a very good indicator of life on this planet!
- Direct Imaging
The third method weighs in at only 33 discoveries. It is the method of direct imaging or ‘Taking Pictures’ where astronomers can actually take pictures of the planets themselves by eliminating the brightness of their central star. Exoplanets are much much dimer than their star so it is extremely difficult to be able to block out this glare so we can see the planet itself but this method is at the forefront of future exoplanetary science. An analogy would be like trying to take a detect a fairylight in front of a floodlight. Instruments called Coronagraphs are added onto telescopes to act as light blockers or ‘Starshades’ that block the star’s light before it even enters the telescope. Direct imagining is a promising method of the future which would allow us to identify things like oceans and landmasses on the surface of planets.
- Gravitational Microlensing
Only 18 planets discovered here but it is a finicky one – nickname, ‘Light through a Lens’. Gravitational microlensing happens when light from a distant star is bent and focused by gravity as a planet passes between the star and Earth. The phenomenon of gravitational lensing was discovered by Einstein in this theory of General Relativity. These lensing events cannot be predicted and as such observations need to cover a large part of the sky over a large period of time. Alongside them being very quick, fleeting events, this makes method quite inefficient at planet detection.
- Astrometry: Minuscule Movements
Finally finishing up in last position with 2 planets we have Astrometry, who NASA nicknames ‘Miniscule Movements’. This is very similar to the first, Radial Velocity but in this case the wobble of the star in space (due to the gravitational pull of the orbiting planet) is actually observed through direct imaging. A series of pictures are taken of the sky and then the distance between the stars is compared in each shot, if a star have moved in the relation to the others it can be grounds for having an orbiting exoplanet.
The Strange New Worlds
Exoplanets are categorised into broad planet types by radius (compared to solar system objects) and temperature. As such the most common types of exoplanets are ‘Jupiter-type’, ‘Neptune-type’ and ‘Super-Earth’ which is a planet typically 1.5 to 2 times the size of the Earth. Jupiter types tend to be hot and as such ‘Hot-Jupiters’ make up most of the known exoplanets as they are big and bright (due to their heat) which makes them easiest to detect.
Now open this link alongside the post for a bit of visual fun as we talk: https://exoplanets.nasa.gov/alien-worlds/strange-new-worlds/
Here we have a couple of the weirdest planets out there. Worlds where it rains glass sideways, egg shaped worlds close to being torn apart, worlds as light has styrofoam, worlds frozen at minus 370 degrees Fahrenheit, worlds with flowing lava rivers, worlds living in eternal darkness, the list goes on… The information about the size, shape and environment of the planets is all gathered from methods such as doppler and transit , though the images themselves are artists concepts for now. An excellent description of each of these wonderfully wacky worlds is given by NASA so I won’t try to compete, taken a little look around.
What the Future Holds
In August this year came the discovery of Proxima Centauri-b an Earth-sized planet orbiting our closest star, Proxima Centauri only 4.22 light-years away. Although the planet appears to be in the orbit of the star’s habitable zone astronomers are still unsure whether the planet is a rocky dense object or more gaseous. The planet’s surface temperature is also unknown and to answers these questions and more such whether liquid water could exist on the surface we need to be able to conduct atmospheric analysis. Therefore we need to use the transit method – but the tricky part is, although all planets orbit, not all planets transit. Transit is an Earth-specific term which means the planet passes in front of its host star along our line of sight. By this I mean the Earth, planet and the star are all roughly lined up… but if the planet orbits at a slightly different angle from our point of view on Earth we may not be able to see it on its passing journey and hence can’t use the transit method to learn more. This we what we need to find out to learn more about Proxima Centauri-b.
Though if the findings are positive, when/if we as a species master interstellar travel this will certainly be the first candidate to be visited. Far far in the future, if one is very optimistic about the advancement of the human race and their investment in space exploration perhaps planet hopping will become the equivalent of island hopping. NASA also likes to indulge in this fantasy with the idea of the ‘Exoplanet Travel Bureau’ which I find very entertaining. Take a look at some of the artwork (which I find very quaint and retro for such a futuristic idea).
So there we have it a brief history of exoplanetary science, methods of detection and little peak into the weird and the wacky. Watch this space, exoplanetary science really is just getting started… | 0.948828 | 3.703099 |
Scientists want to search for life on Jupiter’s moon. They’re starting in Antarctic oceans.
An autonomous robot is practicing to explore Europa.
By Justin Lawrence, Planetary Science, Georgia Institute of Technology
The harsh and icy ocean surrounding Antarctica may seem like a strange place to be doing research about Jupiter, but since 2014, a team of Georgia Tech engineers and scientists in Britney Schmidt’s Planetary Habitability and Technology Lab, where I’m a graduate student, has been designing, building — and sometimes breaking — an underwater robot there. The robot, named Icefin, will eventually help the team learn about ocean worlds in other parts of the solar system, as well as exploring beneath Antarctic ice along the way.
The environments may be more similiar than you might think: as it turns out, Earth isn’t the only place in our solar system with an ocean. Odds are you’ve heard of Europa, one of Jupiter’s moons. Originally discovered by Galileo in 1610, Europa’s icy surface is chilled to about 110°Kelvin (or -274°F). But as Jupiter’s immense gravity squeezes Europa like a stress ball, the heat produced by that friction provides enough energy to keep its ocean from freezing solid. Add a rocky core with a composition similar to Earth’s, and the possibility of hydrothermal activity at the seafloor, and Europa could be just the kind of place to raise your simple, single-cellular kids — much the same way life may have begun here over 3.5 billion years ago.
“As far as we know, Europa is the only planet in the solar system that has had many of the same qualities as Earth over the last 4.5 billion years,” says Schmidt, the head of the Icefin team. Though there are other ocean worlds too, like Saturn’s moon, Enceladus, a diminutive satellite that actively vents saline liquid into space, Europa is the closest and best bet in our search for life off Earth.
But it’s not exactly a hospitable environment for research: While the ocean is liquid, the frozen crust certainly isn’t, and it’s tens of kilometers thick. That’s where Icefin and the Antarctic come in. Icefin is shaped like a torpedo, and designed to work in deep water and autonomously at great distances. It’s 12 feet long, but only about 10 inches wide, enabling it to fit through narrow holes in the ice, which is key to accessing oceans both on Earth and, in the future, Europa.
Ice also presents additional challenges beyond just gaining access to the ocean. Water blocks navigational signals, which is why GPS doesn’t work underwater here on Earth. So Icefin will have to be able to map out its environment in real time. Here too, the oceans below Antarctica’s ice shelves actually make for a decent dress rehearsal — they’re both relatively isolated from the ‘normal’ open ocean environment and essentially unexplored.
Another hurdle the researchers face is the communication delay over space’s vast distances — Jupiter is over 40 light minutes away at its nearest, meaning radio signals (which travel at the speed of light) will take 40 minutes each way from Earth. So robots deployed in Europa’s ocean will need to be able to think for themselves without constant human intervention, as well as recording what they find. The researchers have practiced artificially delaying communications to Icefin to simulate real mission conditions with limited human input, although the team usually bends the rules and uses fiber optic tethers for real time data and to make sure they can haul Icefin back. It’s always a bit nerve-wracking when we deploy Icefin, even when the vehicle is working perfectly; the ice varies in thickness and hardness, depths are unknown, currents can be unpredictable, and at a few of our sites we share the access holes with seals.
Perhaps the team’s biggest challenge, however, is deciding what set of observations a future life-finding mission would have to make to conclusively state that life is present. One of the primary questions they have to answer is whether they’re designing sensors for something that looks like terrestrial life as we know it, or something entirely different. Other forms of life might have evolved to take utterly different forms, and may not even use familiar metabolisms or molecules like DNA. And of course, whatever instruments they create have to fit on a 10-inch robot.
So far, the team has decided to equip Icefin with a few essentials for its underwater search: cameras, sonar, and sensors to measure temperature and salinity. It will also have the ability to measure oxygen, pH, dissolved organics, or chemical imbalances in the water that suggest nearby hydrothermal inputs.
This information can broadly indicate if a region is habitable — at least, to life as we know it — but can’t necessarily say if anything is actually living there. For that, the team is now designing more complicated tools, such as miniaturized cell counters, about the size of a deck of cards, and compact microscopes capable of capturing 3D images of particles in the water column.
Fortunately researchers will have the next several decades to refine both the technology and the design before launching it toward Europa, giving them plenty of opportunities to explore Antarctica. Early studies have discovered entirely new kinds of life in the ice, with unique adaptations not seen anywhere else in the world.
Robotic systems are improving too, as underwater vehicles gain the ability to map and sample environments under ice autonomously. Hopefully as our understanding of how to look for life on Earth evolves, we’ll be able to apply these lessons in deciding what to pack for a trip to Europa.
This story originally appeared on Massive Science, an editorial partner site that publishes science stories written by scientists. Subscribe to their newsletter for even more science delivered straight to you. (CC BY-ND 4.0) | 0.830204 | 3.853703 |
It’s definitely one of a kind: a hyperactive comet shaped like a peanut that spews water.
But, this comet could reveal to scientists -- like those at the University of Maryland -- how our solar system was formed.
Scientists have close-up pictures of Hartley 2, the first comet of its kind to be visited by a spacecraft during a flyby, as reported in this week’s issue of the journal Science.
The mission that visited the comet, known as EPOXI, was started at the University of Maryland, according to Associate Director of University Communications Lee Tune.
“The mission started at University of Maryland, was pitched to NASA and has been led by the university the whole time,” Tune said.
Larson described the mission as a discovery program, which was led by University of Maryland astronomer Michael A’Hearn, who partnered with NASA to build and operate a spacecraft.
According to NASA EPOXI Project Manager Tim Larson, this comet is significant because of its unique size and volatility.
“Hartley 2 is the smallest comet that we have visited to date and it is by far the most active comet that we have visited to date,” Larson said.
Dry ice inside the comet is heated by the sun, which turns the material into carbon dioxide gas. The material is then re-deposited to other parts of the comet and creates its smooth waist.
Scientists are trying to figure out which parts of the comet are primordial and which are evolutionary to learn more about the origins of our solar system. | 0.817182 | 3.038389 |
The Shape of the Universe
By Andrew Hall
Breaking news for EU Theory – cosmic scale structure largest yet detected in the Universe. Presents quandary for ‘Big Bangers.’
The result of a gamma ray burst detection survey is shown in the featured image from JPL. Each blue dot represents a gamma ray burst (GRB) detected by the team as observed relative to the Milky Way. The discovery team of Hungarian and U.S. astronomers are calling the structure a “ring.”
The nine GRB’s at center of the photo appear to form a spiral, not a ring. Regardless, that ‘ring’ is measured at 1,720 Mega-parsecs – that’s five billion light years. The ring is believed to be 2,770 Mpc distant, in the 0.78 < z < 0.86 range for red shift.
Statistical analysis indicates a one in 20,000 probability this complex formation isn’t chance. The findings were published on July 27 in the Monthly Notices of the Royal Astronomical Society.
Team leader, Lajos Balazs of Konkoly Observatory in Budapest, told Phys.org, “Until now, GRBs are the only objects for which we know the spatial distribution in the whole observable universe. All other objects are complete only in a restricted part of the sky. Our discovery has revealed a large-scale regular feature not known before. Large scale objects like GRB groups have been known already, but such a regular circular structure was a surprise.”
The findings claim a ring, but the astronomers told Phys.org they believe the shape to be a visual impression, and may actually be a spheroid seen head-on. They speculate it may be caused by a spatial harmonic of large-scale matter density distribution.
GRB’s are the brightest events seen in the Universe, thought to result from hyper-nova of massive stars collapsing into back holes, or two neutron stars coalescing. They are extremely rare, transient phenomena. Neutron stars coalescing are a class of GRB that last less than two seconds. Long GRB’s, considered stellar hyper-nova, last from seconds to hours. The article did not state whether these were long, or short GRB’s.
Either way, it makes the pattern all the more remarkable – they caught nine in a structure blinking, which suggests not only spatial, but temporal relationship. The article did not give the time frame, or duration of the GRB’s detected, but said the astronomers seek to collect more GRB’s to study the temporal framework of such events.
They seek to explain a gravity induced “harmonic” that causes massive stars separated by billions of light-years to go hyper-nova, like bullets in a revolver. Good luck.
This can’t be explained by standard theory. It violates the basic mainstream assumptions for CP and the Big Bang.
The Cosmological Principle (CP) sets a theoretical upper limit to large-scale structure of 1.2 billion light years. According to Big Bang theory, the universe is homogeneous and isotropic, so matter should evenly distribute in all directions.
Large-scale structure is detected in the cosmic filaments that string galaxies together, but such structures are under 150 Mpc. This is five times as large according to the astronomer’s findings. If confirmed, the researchers themselves say, their findings refute CP theory.
The scale they estimate is based on gravity model assumptions about red shift. The findings suggest a) theory of red-shift is wrong, and therefore estimates of size and distance are wrong, b) the theory of CP is wrong, c) the theory of GRB’s is wrong, or d) all of the above.
Electric Universe picks, d) all of the above.
Red shift – The researchers’ estimate of scale is dependent of the notion of cosmological red shift caused by an expanding Universe. Halton Arp, the most respected and prolific astronomer of his day, proposed a mechanism for intrinsic red shift based on observations of quasars imbedded in galaxies – a mechanism not related to distance. He describes his theory, and its vehement dismissal by mainstream science in his book, “Seeing Red.” For more information, see Halton Arp present his findings on unusual galaxies.
Mainstream science refused to acknowledge his observations, instead convincing themselves the presence of high red-shift quasars in low red-shift galaxies to be a visual illusion caused by gravitational lensing. With astonishing dishonesty, they claimed to be unable to reproduce observation of filamentary connections between galaxies and quasars found by Arp, even though amateur astronomers with home-based telescopes have done so quite easily.
GRB – EU suggests GRB’s are the result of double layer explosions in plasma filaments. Double layers were described in 1929 by plasma pioneer and Nobel laureate Irving Langmuir. They form when electric charge flows through plasma. They are the cell-like walls of a plasma conduit, formed by counter-rotating, wrapped magnetic fields that give structure to the Berkeland current, capable of carrying and accelerating charge across vast distance in space.
EU concept of GRB’s is described more fully in these articles by Stephen Smith. Instability in the double wall will cause a discharge – a cosmic scale lightning arc. Lightning produces gamma rays, as detected in terrestrial lightning. You can read more on terrestrial gamma ray flashes at NASA.
That gamma rays are commonly produced by known electrical phenomena is significant to understanding how well EU predicts such events with known physics, and how far Big Bang theory must reach beyond known physics to invent theoretical, but unobserved phenomena such as hyper-nova, black holes, dark energy, dark matter and neutron stars to explain the observable universe.
CP theory – Many EU theorists suspect that we live in a steady state universe not dependent on assumptions of isotropic, homogeneous creation-from-nothing, as described by Big Bang.
Nevertheless, it also predicts large-scale structure, as seen in cosmic filaments and the collimated “jets” of active galaxies that extend thousands of light years. Even if the spiral feature is much closer, it still covers 43 degrees of sky, suggesting it is enormous even if it is very close.
At whatever size and distance, plasma phenomena are scalable to accommodate. For a comprehensive description of large-scale phenomena and Birkeland currents, see Donald Scott present “Modeling Birkeland Currents, Part 1” and “Modeling Birkeland Currents, Part 2” in his EU2015 Workshop presentations.
My observation – The spiral appears very much like observations made by Halton Arp, who theorized quasars are birthed from active galactic nuclei through spiral arms.
The Whirlpool galaxy exhibits spiral structure in this NASA Hubble photo, to which I overlaid a trace of the GRB pattern to compare geometry. A tenth outlier GRB from the survey (yellow) is included that appears to belong to the spiral suggested.
Perhaps we are looking down the throat of a cosmic scale z-pinch, producing a new family of galaxies.
Perhaps it is evidence of the current that gave life to our own family of galaxies long ago – it seems pointed in the right direction.
Or perhaps, these are instabilities in the double wall of the heliosphere, where galactic current feeds our Sun.
The findings should stimulate lively discussion in the EU Community. This is certainly evidence in its favor.
Andrew Hall is an engineer and writer, who spent thirty years in the energy industry. He can be reached at [email protected] or https://andrewdhall.wordpress.com/ | 0.827815 | 3.754012 |
(CNN) A mysterious cigar-shaped object spotted tumbling through our solar system last year may have been an alien spacecraft sent to investigate Earth, astronomers from Harvard University have suggested.
The object, nicknamed ‘Oumuamua, meaning “a messenger that reaches out from the distant past” in Hawaiian, was first discovered in October 2017 by the Pan-STARRS 1 telescope in Hawaii.
Since its discovery, scientists have been at odds to explain its unusual features and precise origins, with researchers first calling it a comet and then an asteroid, before finally deeming it the first of its kind: a new class of “interstellar objects.”
Now, a new paper by researchers at the Harvard Smithsonian Center for Astrophysics raises the possibility that the elongated dark-red object, which is 10 times as long as it is wide and traveling at speeds of 196,000 mph, might have an “artificial origin.”
“‘Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization,” they wrote in the paper, which has been submitted to the Astrophysical Journal Letters.
The theory is based on the object’s “excess acceleration,” or its unexpected boost in speed as it traveled through and ultimately out of our solar system in January 2018.
“Considering an artificial origin, one possibility is that ‘Oumuamua is a light sail, floating in interstellar space as a debris from an advanced technological equipment,” wrote the paper’s authors, suggesting that the object could be propelled by solar radiation.
The paper, written by Abraham Loeb, professor and chair of astronomy, and Shmuel Bialy, a postdoctoral scholar, at the Harvard Smithsonian Center for Astrophysics, points out that comparable light-sails already exist on earth.
“Light-sails with similar dimensions have been designed and constructed by our own civilization, including the IKAROS project and the Starshot Initiative. The light-sail technology might be abundantly used for transportation of cargos between planets or between stars.”
In the paper, the pair theorize that the object’s high speed and its unusual trajectory could be the result of it no longer being operational.
“This would account for the various anomalies of ‘Oumuamua, such as the unusual geometry inferred from its light-curve, its low thermal emission, suggesting high reflectivity, and its deviation from a Keplerian orbit without any sign of a cometary tail or spin-up torques.”
‘Oumuamua is the first object ever seen in our solar system that is known to have originated elsewhere.
At first, astronomers thought the rapidly moving faint light was a regular comet or an asteroid that had originated in our solar system.
Comets, in particular, are known to speed-up due to a process known as “outgassing,” in which the sun heats up the surface of the icy comet, releasing melted gas. But ‘Oumuamua didn’t have a “coma,” the atmosphere and dust that surrounds comets as they melt.
Multiple telescopes focused on the object for three nights to determine what it was before it moved out of sight.
“We are fortunate that our sky survey telescope was looking in the right place at the right time to capture this historic moment,” NASA Planetary Defense Officer Lindley Johnson said in a statement last year.
“This serendipitous discovery is bonus science enabled by NASA’s efforts to find, track and characterize near-Earth objects that could potentially pose a threat to our planet.” | 0.935747 | 3.290962 |
Authors: Toni Engelhardt, Robert Jedicke, Peter Veres, Alan Fitzsimmons, Larry Denneau, Ed Beshore, Bonnie Meinke
First Author’s Institution: Institute for Astronomy, University of Hawaii and Technical University of Munich
Status: Published in the Astronomical Journal, open access
Gas and dust permeate interstellar space, and the current picture of planetary system formation hints that larger objects should also occupy the space between the stars and even enter our solar system. The question is—how many?
In our current understanding of how planetary systems form, most of the material in the nascent protoplanetary disk is lost to interstellar space; the strong winds of young stars expel the raw material for planet formation to interstellar space, and gravitational interactions between planetesimals eject many would-be planets. In the solar system, our best bet is that the giant planets migrated from their birthplaces to their current positions, disturbed the orbits of planetesimals—asteroids, comets, and possibly even other young planets—and launched them from the solar system.
If giant planets in other planetary systems undergo similar migrations, interstellar space should be teeming with rogue planetesimals and debris. These wayward objects could encounter the solar system and become entangled in the gravitational web of the Sun. In theory, their unusual trajectories or compositions would give clues as to their extrasolar origins. However, there are no confirmed discoveries of interstellar objects masquerading as members of our solar system.
In this paper, the authors use the fact that we don’t observe interstellar objects (ISOs) to place an upper limit on the number density of these objects in the Milky Way. (Here, number density means the average number of ISOs per cubic astronomical unit.) Knowing the prevalence of ISOs is important because it can tell us more about the early stages of planet formation and our chances of finding interstellar interlopers in the solar system.
To make an estimate of the ISO number density, the authors modeled a synthetic ISO population distributed throughout the solar system (Figure 1). They then determined the likelihood of these objects being detected and identified as ISOs given the observing capabilities of three solar system surveys: Pan-STARRS1, the Mt. Lemmon Survey, and the Catalina Sky Survey. In order for an object to be tagged as a possible ISO, it must be bright enough to be detectable and have an atypical enough trajectory to be tapped for follow-up observations. This method allowed the authors not only to place an upper limit on the number of ISOs, but also to hint as to what we might glean from the objects that we detect.
The authors found that the ISOs detected by the surveys in their simulations have different characteristics from the input population. This is largely due to the limitations of the surveys; objects fainter than the limiting magnitude or moving very quickly or very slowly will evade detection, which limits the sizes and orbits of objects that will be detected. The results also depend upon whether or not the objects display comet-like behavior—sublimating and brightening as they travel close to the Sun. For example, Figure 2 compares how far the simulated (left) and detectable (right) ISO populations are from the Sun.
To date, no survey has definitively identified any object with the unusual trajectory and composition expected of an ISO. This could mean that our assumption that other planetary systems form similarly to our own—with gas and ice giants ejecting planetesimals as they migrate—is fundamentally flawed. Another possibility is that we don’t yet understand how a captured object would behave within the confines of the solar system. As a result, it’s possible that past surveys detected ISOs, but they were ignored based on our current search criteria. Future surveys, such as the one that will be conducted using the Large Synoptic Survey Telescope, will have greater detection capabilities for solar system bodies, increasing our chances of observing ISOs passing through or trapped within the solar system. | 0.872797 | 4.090197 |
Authors: Vasilii V. Gvaramadze, Götz Gräfener, Norbert Langer, Olga V. Maryeva, Alexei Y. Kniazev, Alexander S. Moskvitin and Olga I. Spiridonova
First Author’s Institution: Sternberg Astronomical Institute, Lomonosov Moscow State University, Moscow, Russia
Status: Open access on arXiv
You may have read about the ongoing debate over the progenitors of Type 1a supernovae. One of the proposed scenarios for producing a Type 1a supernova is the merger of two white dwarfs. When the total mass of the merging white dwarfs exceeds the Chandrasekhar limit, the merger product can go up in flames in a thermonuclear explosion that gives rise to a Type 1a supernova. But what happens if the merger product avoids this fate? Today’s paper reports the discovery of an object that may have done just that!
A merger product that avoids going supernova is expected to form a nebula, with a hot, highly magnetized, fast-rotating central star. The nebula would be hydrogen- and helium-free, which makes sense given that white dwarfs are typically composed of carbon and oxygen. The star could proceed to survive for tens of thousands of years before its ultimate collapse, likely leaving behind a neutron star!
The authors of today’s paper were looking for circumstellar nebulae when they found a new one in the constellation Cassiopeia. They were even able to identify the central star of the nebula. Fig 1 shows the nebula as well as the star, both of which we will refer to by the same name: WS35.
Figure 1. The upper two panels show the WISE (Wide-field Infrared Survey Explorer) infrared images of the nebula WS35 at different intensities, highlighting its structural features. The nebula appears as a circular shell with ragged edges (top right) but the higher contrast image (top left) also reveals a diffuse halo around the shell. The bottom left panel is also a WISE image at a different wavelength while the bottom right image is from IPHAS (INT Photometric Hα Survey) and shows no optical counterpart for the nebula. The circles indicate the position of the central star. Figure 1 in the paper.
Follow up spectroscopy of WS35 was done using the Russian 6 meter telescope and revealed a spectrum dominated by emission lines from the central star (see Fig 2). Once you have the spectrum of a star, you can try to fit it in order to deduce some of its properties. Stellar atmosphere models are used to predict the observed spectrum based on parameters such as the temperature and composition of the star. The authors used a (tailored) stellar atmosphere model and found that they could reproduce the observed spectrum quite well. The surface temperature of the star was determined to be about 200,000 K. Its chemical composition appears to be dominated by oxygen and carbon, without any hydrogen or helium. Stars that are both hot and free of hydrogen and helium are rare. In fact, very few such stars are known in the Milky Way!
While the spectrum looks like that of oxygen-rich Wolf Rayet stars, the lines we see here are much stronger and broader. The authors inferred an unusually high stellar wind velocity of ~16,000 km/s. Such high velocities are not seen for normal, radiation-driven winds. They can, however, be explained by invoking rapid rotation and strong magnetic fields that aid the wind acceleration. This aligns nicely with the white dwarf merger scenario since stellar mergers are expected to generate strong magnetic fields.
Figure 2. Observed optical spectrum (black line) of WS35. The x-axis gives the wavelength of the radiation and the y-axis gives the corresponding flux. The best fit model (red line) is also shown. The lower red line shows the continuum flux for the model. Figure 2 in the paper.
The merger scenario is further supported by the fact that models of super-Chandrasekhar mass merger remnants can match the properties of WS35 very well. Not only do the models fit the Hertzsprung-Russell diagram location of WS35, they also predict extreme mass loss during and after merger, with the eventual formation of a hydrogen- and helium-free circumstellar nebula. Fig 3 shows the position of the star on the HR diagram, well-reproduced by a recent model of the post-merger evolution of such remnants. The star’s luminosity was inferred based on its Gaia distance. The temperature of W35 is very high and it appears to be almost at the endpoint of its post-merger evolution.
Figure 3. WS35 (red cross) on the Hertzsprung-Russell diagram. The black line represents the evolutionary track of a carbon-oxygen white dwarf post-merger model from Schwab et al. (2016). The colored dots (1-4) indicate various important stages as the remnant evolves and burns. The time elapsed between the stages is also given. Point 1 is reached in only ~100 years, evolution from point 1 to point 4 takes up to ~20 kyr, and the track ends at ~25 kyr. Figure 3 in the paper. For the curious, also see Figure 11 in Schwab et al. 2016.
So, what happens next? WS35 will eventually collapse and the authors believe that it is likely to produce a neutrino-flash and a gamma-ray burst, followed by a very fast and subluminous Type Ic supernova. For now though, the existence of this object tells us that it’s certainly possible for a super-Chandrasekhar mass merger to avoid thermonuclear explosion. | 0.827944 | 3.945345 |
Photo: This image, taken with the NASA/ESA Hubble Space Telescope, shows a massive galaxy cluster, about 4.6 billion light years away. Along its borders four bright arcs are visible; these are copies of the same distant galaxy, nicknamed the Sunburst Arc.
The Sunburst Arc galaxy is almost 11 billion light-years away and the light from it is being lensed into multiple images by gravitational lensing. The Sunburst Arc is among the brightest lensed galaxies known and its image is visible at least 12 times within the four arcs.
Three arcs are visible in the top right of the image, the fourth arc in the lower left. The last one is partially obscured by a bright foreground star, which is located in the Milky Way. Credit: ESA/Hubble, NASA, Rivera-Thorsen et al.
Astronomers using the NASA/ESA Hubble Space Telescope have observed a galaxy in the distant regions of the Universe which appears duplicated at least 12 times on the night sky. This unique sight, created by strong gravitational lensing, helps astronomers get a better understanding of the cosmic era known as the epoch of reionisation.
SulutPos.com, Garching, Germany – This new image from the NASA/ESA Hubble Space Telescope shows an astronomical object whose image is multiplied by the effect of strong gravitational lensing. The galaxy, nicknamed the Sunburst Arc, is almost 11 billion light-years away from Earth and has been lensed into multiple images by a massive cluster of galaxies 4.6 billion light-years away .
The mass of the galaxy cluster is large enough to bend and magnify the light from the more distant galaxy behind it. This process leads not only to a deformation of the light from the object, but also to a multiplication of the image of the lensed galaxy.
In the case of the Sunburst Arc the lensing effect led to at least 12 images of the galaxy, distributed over four major arcs. Three of these arcs are visible in the top right of the image, while one counterarc is visible in the lower left — partially obscured by a bright foreground star within the Milky Way.
Hubble uses these cosmic magnifying glasses to study objects otherwise too faint and too small for even its extraordinarily sensitive instruments. The Sunburst Arc is no exception, despite being one of the brightest gravitationally lensed galaxies known.
The lens makes various images of the Sunburst Arc between 10 and 30 times brighter. This allows Hubble to view structures as small as 520 light-years across — a rare detailed observation for an object that distant. This compares reasonably well with star forming regions in galaxies in the local Universe, allowing astronomers to study the galaxy and its environment in great detail.
Hubble’s observations showed that the Sunburst Arc is an analogue of galaxies which existed at a much earlier time in the history of the Universe: a period known as the epoch of reionisation — an era which began only 150 million years after the Big Bang .
The epoch of reionisation was a key era in the early Universe, one which ended the “dark ages”, the epoch before the first stars were created when the Universe was dark and filled with neutral hydrogen . Once the first stars formed, they started to radiate light, producing the high-energy photons required to ionise the neutral hydrogen .
This converted the intergalactic matter into the mostly ionised form in which it exists today. However, to ionise intergalactic hydrogen, high-energy radiation from these early stars would have had to escape their host galaxies without first being absorbed by interstellar matter. So far only a small number of galaxies have been found to “leak” high-energy photons into deep space. How this light escaped from the early galaxies remains a mystery.
The analysis of the Sunburst Arc helps astronomers to add another piece to the puzzle — it seems that at least some photons can leave the galaxy through narrow channels in a gas rich neutral medium. This is the first observation of a long-theorised process . While this process is unlikely to be the main mechanism that led the Universe to become reionised, it may very well have provided a decisive push.
Pan of the Sunburst Arc
Ionisation is the process of gaining or losing electrons to leave electrically charged particles. The era is known as reionisation because, after the Big Bang, matter formed first into protons and electrons. Then, during the era of recombination — about 380 000 years after the Big Bang — neutral hydrogen formed from these particles for the first time.
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
The international team of astronomers in this study consists of T. Emil Rivera-Thorsen (University of Oslo, Norway), Håkon Dahle (University of Oslo, Norway), John Chisholm (Université de Genève, Switzerland; University of California Santa Cruz, USA), Michael K. Florian (NASA Goddard Space Flight Center, USA), Max Gronke (University of California Santa Barbara, USA), Michael D. Gladders (University of Chicago, USA), Jane R. Rigby (NASA Goddard Space Flight Center, USA), Guillaume Mahler (University of Michigan, USA), Keren Sharon (University of Michigan, USA), Matthew Bayliss (MIT-Kavli Center for Astrophysics and Space Research, USA) and included data from Hubble programs 15418 and 15101.
Image credit: ESA, NASA, E. Rivera-Thorsen et al.
ESA/Hubble Photo Release | 0.879752 | 3.915453 |
The venerable Solar Heliospheric Observatory (SOHO), run by NASA and ESA, has discovered a new comet faintly visible right now with the naked eye from Earth's southern hemisphere.
As SOHO scanned the heavens for sources of ultraviolet light, the orbiting telescope clocked a bright blob moving through the Solar System.
That blob is a comet, which is shedding water vapor from its icy core as it's melted by the Sun's heat. The solar radiation is also splitting the liquid into hydrogen atoms and hydrogen-oxygen pairs. The cloud of hydrogen atoms emitted a type of ultraviolet radiation called Lyman-alpha light that's visible to the satellite's Solar Wind ANisotropies (SWAN) instrument.
Amateur astronomer Michael Mattiazzo spotted the comet – named C/2020 F8, or SWAN after the instrument – after spotting it hurtling by Earth in April using publicly available data from the probe.
Professor Michael Combi, of the University of Michigan’s Climate and Space Sciences and Engineering department and a member of the SWAN team, estimated that by April 15 the space rock was spewing about 1,300 kilograms of water vapor per second.
"This is already three times more than Comet 67P/Churyumov-Gerasimenko at its best, when it was visited by ESA's Rosetta mission between 2014 and 2016," said Jean-Loup Bertaux, former principal investigator and proposer of the SWAN instrument.
ATLAS flubbed: Comet heading our way takes one look at Earth, self-destructs into house-sized chunksREAD MORE
Although the comet made its closest approach on May 13 when it was about 53 million miles from Earth, it should stay just about visible throughout the end of May and into June. The best time to catch it is just before sunrise in the southern hemisphere; the object should be, in theory, just bright enough to be spotted with the naked eye, according to NASA.
Comet SWAN is the 3,932nd ice ball clocked using SOHO, an admirable achievement for the 25-year-old satellite considering it was planned to operate for just two years to map solar winds. Most of those discoveries, however, were made using its coronagraph instrument that studies the Sun’s outer shell while blocking out its central sunlight.
“It's extremely exciting that our sun-watching observatory has spotted so many comets since its launch in 1995," said Bernhard Fleck, ESA SOHO project scientist. "We are eagerly awaiting, along with comet enthusiasts around the world, for the 4,000th discovery, which might happen real soon."
That job has mostly been fulfilled by armchair astronomers scrolling through images taken from SOHO and NASA’s Solar Terrestrial Relations Observatory (STEREO) as part of the online Sungrazer Project.
“Almost all of SOHO's comet discoveries so far have been made by citizen scientists scouring images returned by SOHO's LASCO instrument," said Karl Battams, a lead researcher on the project and a comet expert at the US Naval Research Laboratory. ® | 0.884542 | 3.856681 |
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
May 4, 1998
Explanation: It looked like a ring on the sky. Hundreds of years ago astronomers noticed a nebula with a most unusual shape. Now known as M57 or NGC 6720, the gas cloud became popularly known as the Ring Nebula. It is now know to be a planetary nebula, a gas cloud emitted at the end of a Sun-like star's existence. As one of the brightest planetary nebula on the sky, the Ring Nebula can be seen with a small telescope in the constellation of Lyra. The Ring Nebula lies about 4000 light years away, and is roughly 500 times the diameter of our Solar System. In this recent picture by the Hubble Space Telescope, dust filaments and globules are visible far from the central star. This helps indicate that the Ring Nebula is not spherical, but cylindrical. Perhaps the Ring Nebula would appear differently if viewed sideways.
Authors & editors:
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
&: Michigan Tech. U. | 0.827323 | 3.007683 |
30P/Reinmuth 1 was discovered by Karl Reinmuth at
The comet is of short period. Initially the period was 7.23 years and the perihelion distance 1.86AU, but a fairly close approach to Jupiter in 1937 changed the orbit and moved it to a slightly longer period (a maximum of 7.69 years) and a more distant perihelion (2.04AU), making it much fainter, such that it could no longer get brighter than magnitude 17. Since then the comet has progressively moved back to its earlier orbit and currently has a period of 7.32 years and perihelion at 1.87AU.
The 2002 apparition
30P/Reinmuth will pass perihelion on December 24th and will peak at around magnitude 14.5. Like many old, evolved comets it brightens rather rapidly as it approaches the Sun. This is due to the mantle of dust that has built up over the nucleus that prevents the Sun's heat reaching the ices until sufficient heat has leaked through. The comet will thus increase in brightness very rapidly through November and December. This is a much better return than 1995 when the comet never brightened more than to magnitude 16.5.
Maximum brightness was reached approximately 2 months after perihelion. As caan be appreciated from the CCD total magnitude estimates, the comet reached about magnitude 13 at maximum.
CCD observations in a 10 arcsecond aperture by:
CCD aperture photometry in apertures of 0'.3, 0'.5, 1'.0, 2'.2 by: | 0.807975 | 3.622371 |
Albert Einstein – The Father of Modern Life?
Do you know how Einstein changed our modern life? Few might know the wide-reaching impact he has had on almost all forms of science.
Therein lies possibly the most tangible impact Einstein had on science–he is one of the most influential foundation-setters in history, both directly and indirectly. He is truly the rare figure who made impacts even with half-completed theories and concepts that did nothing more than introduce new ideas or ways of thinking about a subject. Einstein published countless works on theories that changed how people viewed a topic, bringing scientific knowledge into a new age.
Many of his theories continue to be applied to new applications even today. If scientific discovery can be compared to creation using building blocks, Einstein provided the blocks that made up the foundation of so many discoveries, both big and small
Einstein was a man who never stopped wondering, never stopped searching, and never stopped asking the “how” behind what we see in the universe.
The Grand Theory of Relativity and GPS
No discussion about Einstein’s impact on the world would be complete without an extensive look at his Theory of Relativity. Published in 1905, the world-famous E=mc2 equation completely changed the way we look at time, space, gravity, energy, and mass.
At its most basic, Einstein’s Theory of Relativity concluded that fast-moving objects appear to have more mass relative to slow-moving objects. This is due to the increase in an object’s velocity which increases its kinetic energy, which also (because the theory also states that mass is equal to energy) increases its mass.
Not only were its impacts on theoretical science far-reaching, the theory had and continues to have practical impacts as well. GPS systems must take into account relativistic effects to function accurately. They do so by speeding up the clocks on the satellites by 38,000 nanoseconds compared to the clocks on Earth.
If no relativistic effects were taken into consideration when determining speed, distance and direction of the signals being sent back to Earth, after just one day your GPS would tell you that your destination is only a half mile away and it would really be five miles further. That’s quite a difference!
LASERs, Atomic Bombs, Solar
Electricity and Remote Controls
As impactful as it was, the Theory of Relativity was not Einstein’s only contribution to the field of physics. For instance, in 1917, Einstein proposed the possibility of stimulated emission. You may have heard of stimulated emission from its inclusion in the term “Light Amplification by Stimulated Emission of Radiation,” or its better-known acronym: LASER.
In a development that can be seen as both positive and negative, Einstein’s work on mass-energy equivalence – which was a precursor to the development of E=mc2 – introduced the idea that tiny articles of mass could be converted into much larger amounts of energy. Later, this work and the related concepts were developed into the concepts of nuclear power and the atomic bomb. While Einstein lamented the destructive world-altering application of his work, nuclear technology has proved useful in a number of constructive ways, including nuclear power.
Surprisingly, Einstein was not awarded a Nobel Prize for his Theory of Relativity. He was, however, given his lone Nobel Prize in 1922 for his work discovering the law of the Photoelectric Effect and its impact on theoretical physics.
Einstein theorized that light could create electricity if it could vary its behavior state; sometimes it behaved like a wave, and sometimes like a particle. In this state, a light particle could deliver enough energy to create an electrical current. And in doing so, he produced a theory that was the foundation for many of the great scientific breakthroughs of our time.
Ever use solar energy or another device that turns light into energy or point the remote control at the television and turn it on? The Photoelectric Effect is the basis for the invention of both. How about having elevator doors not close on you when walking through, or observing lights automatically turn on when it gets dark? The sciences behind all these inventions, among many others, are descended from Einstein’s work on photoelectricity.
CARBON DATING, THE BIG BANG AND PERSON OF THE CENTURY
While the vast majority of Einstein’s work fell under the umbrella of physics, his impact isn’t constrained to work in that one field. In yet another example of how his work transcends segmented areas of study, even some of his most famous physics-based equations are finding varied uses.
The connection between mass and energy shown in the equation E=mc2 explains how biologists and archeologists can use the decay of carbon nuclei in the atoms of organic materials. This information has led to the emergence of carbon dating, which is used in everything from archeological explorations to discoveries of new organisms.
Unsurprisingly, given how much he’s impacted science as a whole, Einstein started and helped develop the entire field of cosmology, which is the science of the origin and developmental observations of the universe. Led by studies of the Big Bang theory (which his theories helped advance), his work led to the discovery of black holes and the possibility of wormholes.
In 1999, Time magazine named Einstein a “Person of the Century.” He is well-deserving of this honor based on the theories and discoveries he achieved and his tangible impact on science and our daily lives.
Not only did his observations provide the theoretical basis for much of today’s scientific fields, they also provided the foundation needed for many great achievements.
In this way, Einstein not only influenced the scientific world, but our entire modern lifestyle. And that’s as profound of an impact someone can have. | 0.809311 | 3.079026 |
‘Excess’ Gamma-Rays at Milky Way’s Core Likely From Pulsars, Not Dark Matter
New research debunks an exciting theory about the mysterious nature of dark matter.
A promising lead about the nature of elusive dark matter may have just dried up.
A mysterious abundance of gamma-rays — the highest-energy light in the universe — at the Milky Way's center is likely being produced by fast-spinning stellar corpses called pulsars, rather than bits of dark matter slamming into each other, a new study suggests.
"Our study shows that we don’t need dark matter to understand the gamma-ray emissions of our galaxy,” co-author Mattia Di Mauro, from the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) in California, said in a statement. [The Hunt for Dark Matter: Images and Photos]
"Instead, we have identified a population of pulsars in the region around the galactic center, which sheds new light on the formation history of the Milky Way," added Di Mauro, who led the analysis for the Fermi LAT Collaboration. This is a group of researchers who used the Large Area Telescope on NASA's Fermi Gamma-ray Space Telescope to study the galaxy's gamma-ray glow.
Hunting for dark matter
Though dark matter apparently neither emits nor absorbs light (hence the name), astronomers know the stuff exists; they have observed its gravity affecting the "normal" matter we can see and touch. Indeed, such work suggests that dark matter makes up about 85 percent of the material universe.
However, scientists still don't know what the mysterious stuff is. One leading hypothesis holds that dark matter is composed mostly of Weakly Interacting Massive Particles (WIMPs). Theoretical physicists think that WIMPs generate gamma-rays when they interact with each other, either via direct annihilation or the production of a fast-decaying secondary particle.
So it was exciting when, several years ago, Fermi spotted an "excess" of gamma-rays near the Milky Way's core that astronomers said could not be explained by traditional sources such as pulsars. Process of elimination seemed to indicate that dark matter — in the form of WIMPs — was responsible.
The researchers behind such studies stressed at the time that this interpretation was tentative and in need of backing by other observations.
Pulsars the culprit?
Such confirmation has yet to materialize.
"Two recent studies by teams in the U.S. and the Netherlands have shown that the gamma-ray excess at the galactic center is speckled, not smooth as we would expect for a dark matter signal," KIPAC's Eric Charles, who contributed to the new analysis, said in the same statement.
"Those results suggest the speckles may be due to point sources that we can't see as individual sources with the LAT because the density of gamma-ray sources is very high and the diffuse glow is brightest at the galactic center," Charles added.
The new study further supports this idea, linking the speckled signal to pulsars.
"Considering that about 70 percent of all [gamma-ray] point sources in the Milky Way are pulsars, they were the most likely candidates," Di Mauro said. "But we used one of their physical properties to come to our conclusion. Pulsars have very distinct spectra — that is, their emissions vary in a specific way with the energy of the gamma-rays they emit. Using the shape of these spectra, we were able to model the glow of the galactic center correctly with a population of about 1,000 pulsars and without introducing processes that involve dark matter particles."
There are other reasons to doubt that the gamma-ray excess is being generated by dark matter, study team members said.
"If the signal were due to dark matter, we would expect to see it also at the centers of other galaxies," Seth Digel, head of KIPAC’s Fermi group, said in the same statement. "The signal should be particularly clear in dwarf galaxies orbiting the Milky Way. These galaxies have very few stars, typically don’t have pulsars and are held together because they have a lot of dark matter. However, we don't see any significant gamma-ray emissions from them."
The team plans to observe the Milky Way's center with radio telescopes, in an attempt to determine if the point sources there are emitting their light in pulses, as pulsars seem to do. (This is just an illusion, however. Pulsars emit light beams continuously in opposite directions; the light appears to flicker because pulsars spin, and their beams are therefore not always pointing at Earth.)
The new study has been submitted to The Astrophysical Journal. You can read it for free at the online preprint site arXiv.org.
Originally published on Space.com. | 0.888226 | 4.010615 |
This is a false color image of Neptune in which smog hazes can be seen in red.
Click on image for full size
Neptune's Smog Hazes
This image of Neptune uses false colors to show where the smog is. The smog of Neptune can be seen in red along the edge of the image.
This smog haze is found very high up in the atmosphere, over the clouds of Neptune. Even though the smog can only be seen in red along the edge of the picture, the smog exists through the entire atmosphere of Neptune.
A patch of bright, white clouds, very high in the atmosphere, can also be seen in this image.
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Neptune was discovered in 1846. But it wasn't discovered using a telescope. Scientists used math instead! They watched Uranus and saw that its orbit was doing weird things. They knew another planet had...more
The picture shows places on Jupiter which are hot. Jupiter is a very warm place, as shown in the picture, sort of like a warm log in the fireplace which gives off heat. Like Jupiter, Neptune also gives...more | 0.842944 | 3.10098 |
Using a new process in planetary formation modelling, where planets grow from tiny bodies called “pebbles,” Southwest Research Institute scientists can explain why Mars is so much smaller than Earth. This same process also explains the rapid formation of the gas giants Jupiter and Saturn, as reported earlier this year.
“This numerical simulation actually reproduces the structure of the inner Solar System, with Earth, Venus, and a smaller Mars,” says Hal Levison, an Institute scientist at the SwRI Planetary Science Directorate.
The fact that Mars has only ten per cent of the mass of the Earth has been a long-standing puzzle for Solar System theorists. In the standard model of planet formation, similarly-sized objects accumulate and assimilate through a process called accretion where rocks incorporated other rocks, creating mountains and then mountains merged to form city-size objects, and so on. While typical accretion models generate good analogues to Earth and Venus, they predict that Mars should be of similar size, or even larger than Earth. Additionally, these models also overestimate the overall mass of the asteroid belt.
“Understanding why Mars is smaller than expected has been a major problem that has frustrated our modelling efforts for several decades,” says Levison. “Here, we have a solution that arises directly from the planet formation process itself.”
New calculations by Levison and Katherine Kretke, Kevin Walsh and Bill Bottke, all of SwRI’s Planetary Science Directorate follow the growth and evolution of a system of planets. They demonstrate that the structure of the inner solar system is actually the natural outcome of a new mode of planetary growth known as Viscously Stirred Pebble Accretion (VSPA). With VSPA, dust readily grows to “pebbles” — objects a few inches in diameter — some of which gravitationally collapse to form asteroid-sized objects. Under the right conditions, these primordial asteroids can efficiently feed on the remaining pebbles, as aerodynamic drag pulls pebbles into orbit, where they spiral down and fuse with the growing planetary body. This allows certain asteroids to become planet-sized over relatively short time scales.
However, these new models find that not all of the primordial asteroids are equally well-positioned to accrete pebbles and grow. For example, an object the size of Ceres (about 600 miles across), which is the largest asteroid in the asteroid belt, would have grown very quickly near the current location of the Earth. But it would not have been able to grow effectively near the current location of Mars, or beyond, because aerodynamic drag is too weak for pebble capture to occur.
“This means that very few pebbles collide with objects near the current location of Mars. That provides a natural explanation for why it is so small,” says Kretke. “Similarly, even fewer hit objects in the asteroid belt, keeping its net mass small as well. The only place that growth was efficient was near the current location of Earth and Venus.”
“This model has huge implications for the history of the asteroid belt,” says Bottke. Previous models have predicted that the belt originally contained a couple of Earth-masses’ worth of material, meaning that planets began to grow there. The new model predicts that the asteroid belt never contained much mass in bodies like the currently observed asteroids.
“This presents the planetary science community with a testable prediction between this model and previous models that can be explored using data from meteorites, remote sensing, and spacecraft missions,” says Bottke.
This work complements the recent study by Levison, Kretke, and Martin Duncan (Queen’s University), which demonstrated that pebbles can form the cores of the giant planets and explain the structure of the outer Solar System. Combined, the two works present the means to produce the entire solar system from a single, unifying process.
“As far as I know, this is the first model to reproduce the structure of the Solar System — Earth and Venus, a small Mars, a low-mass asteroid belt, two gas giants, two ice giants (Uranus and Neptune), and a pristine Kuiper Belt,” concludes Levison. | 0.887848 | 3.996382 |
The Solar System consists of the Sun and its planetary system of eight planets, their moons, and other non-stellar objects. It formed 4.6 billion years ago from the gravitational collapse of a giant molecular cloud.
The vast majority of the system’s mass is in the Sun, with most of the remaining mass contained in Jupiter. The four smaller inner planets, Mercury, Venus, Earth and Mars, also called the terrestrial planets, are primarily composed of rock and metal.
The four outer planets, called the gas giants, are substantially more massive than the terrestrials. The two largest, Jupiter and Saturn, are composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are composed largely of substances with relatively high melting points (compared with hydrogen and helium), called ices, such as water, ammonia and methane, and are often referred to separately as “ice giants”.
Below are some stunning images of our Solar System, taken by photographer Michael Benson for his new book, Planetfall and his exhibition of the same title now at the Washington, D.C. headquarters of the American Association for the Advancement of Science.
By “planetfall,” Benson means “the act or an instance of sighting a planet after a space voyage.”
To make his photographs, Benson peruses through thousands of raw image data, rarely seen by the public, which were collected on missions led by NASA—Cassini, Galileo, MESSENGER, Viking and Voyager, among others—and the European Space Agency. Benson then pieces together the image data into one seamless photograph. It can take anywhere from tens to hundreds of raw frames to arrange, like a mosaic, one legible composite image. Then rendering the photograph in realistic colors adds another layer of complexity.
Click image to enlarge
H/t FOTM’s igor | 0.909055 | 3.087825 |
Hubble reveals interstellar visitor is unlike any local comet
2I/Borisov is like a time capsule from a part of the universe humans might never be able to visit. This comet from another star system is currently visiting our own, and now Hubble has taken the valuable opportunity to study its chemical makeup. The famous Space Telescope reveals that Borisov is very different to any local comet, giving hints about what kind of system it was born in.
As the “2I” designation indicates, Borisov is only the second interstellar object ever detected whizzing through our neighborhood. The first was the oddly oblong asteroid ‘Oumuamua, and while that had plenty to teach us, comets are more active, so astronomers can glean different types of information.
"With an interstellar comet passing through our own solar system, it's like we get a sample of a planet orbiting another star showing up in our own backyard," says John Noonan, an author of the new study.
While it had the chance Hubble turned its attention to Borisov, studying its chemical composition using ultraviolet spectroscopy. By taking observations on four different occasions in December and January, the team watched the specific composition change quickly.
It turns out that Borisov’s coma – the gas cloud trailing off the nucleus – contains three times the amount of carbon monoxide of any local comet. This suggests that it was probably born in a carbon-rich disk of material around a cool red dwarf star.
"These stars have exactly the low temperatures and luminosities where a comet could form with the type of composition found in comet Borisov,” says Noonan.
The key observation is the fact that Borisov continued to burp out carbon monoxide at the same high levels as it retreated away from the Sun. Since carbon monoxide ice melts at a lower temperature than water ice, the comet most likely contains a core of carbon monoxide ice, wrapped in water ice.
"The amount of carbon monoxide did not drop as expected as the comet receded from the Sun,” says Dennis Bodewits, lead researcher on the study. “This means that we are seeing the primitive layers of the comet, which really reflect what this object is made of. Because of the abundance of carbon monoxide ice that survived so close to the Sun, we think that comet Borisov comes from a much colder place and from a very different debris disk around a star than our own.”
The window of observation for 2I/Borisov is closing fast, with the comet expected to vanish from sight in the next few months. But astronomers are hopeful that other interstellar interlopers will appear soon – after all, ‘Oumuamua and Borisov were only two years apart, suggesting that these visitors are fairly common. We just have to keep our eyes open.
The research was published in the journal Nature Astronomy. | 0.886444 | 3.974619 |
Planetary Family Portrait: HR 8799
This image shows the HR 8799 planets with starlight optically suppressed and data processing conducted to remove residual starlight. The star is at the center of the blackened circle in the image. The four spots indicated with the letters b through e are the planets. A team of researchers belonging to a group called Project 1640, which is partly funded by NASA's Jet Propulsion Laboratory, Pasadena, Calif., used the Palomar Observatory near San Diego to obtain detailed spectra of the four planets.
Major Breakthrough: First Photos of Planets Around Other Stars
This 3D representation of the three planets orbiting the star HR 8799 shows the system is located 90 degrees away from the Milky Way galactic center, lower than the sun. (All orbital diameters are greatly exaggerated.)
Light from Faraway Planet Directly Detected
The bright and very young star HR 8799, about 130 light-years away from Earth, hosts a planetary system that looks like a scaled-up model of our own Solar System. 3 giant planetary companions have been detected so far, with masses between 7 and 10 times that of Jupiter and being between 20 and 70 times as far from their host star than the Earth is from the Sun; the system also includes two belts of smaller objects, similar to our asteroid and Kuiper belts. This NACO image shows the star and the middle planet (marked).
Hidden Planet Discovered in Old Hubble Data
This is an artistic illustration of the giant planet HR 8799b. The planet was first discovered in 2007 at the Gemini North observatory. The planet is young and hot, at a temperature of 1500 degrees Fahrenheit. It is slightly larger than Jupiter and may be 10 times more massive.
Four Giant Exoplanets of Star HR 8799 Includes One With Water in its Atmosphere (Infographic)
Unlike most exoplanet discoveries, the system of HR 8799 can be directly viewed by Earth-based telescopes.
HR 8799 Planetary System
This artist's rendering of the planetary system of HR 8799 130 light-years from Earth as it may have appeared at an early stage in its evolution. The image shows the giant exoplanet HR 8799c, as well as a disk of gas and dust, and interior planets. Image added March 14, 2013.
Star HR 8799
The star HR 8799 captured in an infrared image, along with several planets.
New Planets Found Around HR 8799
The left image shows the star HR 8799 as seen by Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) in 1998. The center image shows recent processing of the NICMOS data with newer, sophisticated software. Further processing reveals three planets orbiting HR 8799. The illustration on the right shows the positions of the star and the orbits of its four known planets.
Solar System Around HR 8799
One of the discovery images of the supersized alien solar system around the star HR 8799, about 130 light-years from Earth, obtained by the Keck II telescope using an adaptive optics system and NIRC2 Near-Infrared Imager. The rectangle indicates the field-of view of the OSIRIS instrument. Image added March 14, 2013.
Spectrum of Planet Around HR 8799
Spectrum of planet around HR 8799.
Star HR 8799 as Seen by Hubble's Near Infrared Camera and Multi-Object Spectrometer
This image of the star HR 8799 was taken by Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) in 1998. A mask within the camera (coronagraph) blocks most of the light from the star. Scattered light from HR 8799 dominates the image, obscuring the faint planets. | 0.921148 | 3.450555 |
Ray-tracing software lets researchers visualize science with greater fidelity “Graphics displays have faced a limitation due to their digital nature,” Hanson explained to PhysOrg.com. “For example, handling large ranges in detail is out of the range of standard hardware, such as accelerated graphics cards. With this new system, we can create an accurate, interactive experience, with continuous scaling over different scale ranges. You can wander continuously throughout the universe without any anomalies.”Fu and Hanson’s work tackles several problems that past systems have faced: focusing on objects at different distances, depth perception, and speed. As Hanson explains, it’s a bit like looking at a ladybug on your nose with the galaxy in the background. To improve these areas, the scientists developed a graphics software system that provides a continuously scalable visualization in three dimensions. Citation: In ‘forty jumps,’ scientists model scales of quarks to quasars (2007, January 18) retrieved 18 August 2019 from https://phys.org/news/2007-01-forty-scientists-scales-quarks-quasars.html Hanson and Fu designed their software by extending the powers-of-ten framework, shown for common objects in this table. Image Credit: Andrew Hanson, et al. © 2006 IEEE. Comprehending the smallness of a quark or the hugeness of the observable universe is a challenge that most of us find difficult, yet captivating. Placing vastly different scales side by side to explore their relationship amounts to a task not even computers have mastered efficiently. Recently, scientists Chi-Wing (Philip) Fu and Andrew Hanson have developed a visualization system of the universe that may help scientists, educators and film viewers better understand size on a journey through the universe. The content of the system—stars, galaxies, supernovae, etc.—comes from an extraordinary collection of data from exploration systems such as the Sloan Digital Sky Survey, the Bright Star Catalogue, Hubble and other telescopes. In their study, Fu and Hanson present a “powers-of-ten journey,” starting, e.g., from Earth (107 m) up through the solar system (1013), the Pleiades cluster (1018), the Andromeda galaxy (1023), and beyond (see figure).Like previous computer graphics programs studying outer space, Fu and Hanson predict that this system could not only have use for astronomers and physicists studying the universe, but for educational and commercial purposes, as well. IMAX shows and planetarium presentations have excited young enthusiasts with their realistic animations, and as computational power continues to grow, the public can also benefit from Fu and Hanson’s scale visualization technology.“Our motivation was to create a framework for a real-time digital planetarium,” said Hanson. “With this framework, we’ve created a series of layers of objects across an enormous scale range, all on a single screen.”Citation: Fu, Chi-Wing and Hanson, Andrew J. “A Transparently Scalable Visualization Architecture for Exploring the Universe.” IEEE Transactions on Visualization and Computer Graphics, Vol. 13, No. 1, January/February 2007.By Lisa Zyga, Copyright 2006 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. Because a normal “zoom” feature would take an impractical amount of time due to the vast precision required, Fu and Hanson used a new approach: power-scaled coordinates (PSC). The scientists were inspired by a film called “Powers of Ten” by Eames and Eames, which itself was based on the 1957 children’s book Cosmic View: The Universe in Forty Jumps by Boeke. “We asked ourselves, ‘how do you provide that experience [of the film]?’” said Hanson. “We extend that ‘powers of ten’ framework by making this system interactive instead of pre-computed and pre-stored.”Fu and Hanson’s PSC system works by representing coordinates and vectors using logarithmic scaling methods, enabling the system to handle all scales in a single context for interactive control by the user. One of the novel PSC-based ideas in the architecture is a “depth rescaling method,” which can project objects across extreme scales with the needed precision by distorting the vertices of distant background objects. Also, to accelerate the rendering of objects during navigation, the system uses “environmental caching” and “object disappearance” to develop pre-rendered backgrounds and ignore objects that are not large or luminous enough to appear on the screen. On a desktop computer, the program achieves interactive speeds. Explore further This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. From the top left and moving across, this powers-of-ten journey shows Earth (red line represents the ISS) (107 m), Earth and satellites (108 m), solar system (1013 m), Pleiades (1018 m), extrasolar planets (1018 m), and the Milky Way and Large Magellanic Cloud (1023 m). Image Credit: Andrew Hanson, et al. © 2006 IEEE.
The scientists, P. Panagiotopoulos, D.G. Papazoglou, A. Couairon and S. Tzortzakis, from institutions in Greece and France, have published a paper in a recent issue of Nature Communications in which they show theoretically and experimentally how ring-Airy beams transform into light bullets.An airy beam is a type of light beam that has the distinct feature of forming a parabolic arc as it propagates through space. In fact, it gets its name from the Airy integral, developed in the 1830s by Sir George Biddell Airy to describe the way light bends in a rainbow. In 2011, scientists (including some of the authors of the current paper) experimentally demonstrated an Airy beam in the shape of a ring. In the linear regime, this ring-Airy beam can focus itself into a sharp focal point, which could make it an ideal candidate for precise laser ablation applications in hard-to-reach environments.In the new study, the scientists have investigated the properties of ring-Airy beams in the non-linear regime, and found them to be even more impressive than in the linear regime. The scientists found that the ring-Airy wavepacket reshapes itself into a propagating high intensity light bullet that spreads neither in space nor in time over significantly longer distances than Gaussian beams, which are often used in conventional lasers.The researchers also found that, when the input power is increased, the ring-Airy beam’s focus position is not shifted nearly as much as it is for Gaussian beams. The researchers could mathematically predict the position of the ring-Airy beam’s focus for a given input power, which they confirmed through experiments.These highly focused, high-intensity ring-Airy beam light bullets offer a very high level of control that cannot be achieved with equivalent Gaussian beams, making them ideal for a variety of optical applications ranging from precision materials processing to attosecond drivers. Citation: Scientists create light bullets for high-intensity optical applications (2013, November 12) retrieved 18 August 2019 from https://phys.org/news/2013-11-scientists-bullets-high-intensity-optical-applications.html Journal information: Nature Communications More information: P. Panagiotopoulos, et al. “Sharply autofocused ring-Airy beams transforming into non-linear intense light bullets.” Nature Communications. DOI: 10.1038/ncomms3622 © 2013 Phys.org. All rights reserved. (Phys.org) —Controlling the propagation of high-intensity light beams as they travel through air (or other transparent media) is a challenging task, but scientists have now shown that a relatively new type of light beam called a ring-Airy beam can self-focus into intense light bullets that propagate over extended distances. These well-defined, high-intensity optical wavepackets could have applications in a variety of areas, such as laser micromachining and harmonic generation. Explore further Researchers discover a way to generate an electron Airy beam Compared to two types of Gaussian beams (EEGB and ECGB), the ring-Airy wavepacket has a more precisely focused shape, appearing as a ‘light bullet.’ The wavepacket shapes are shown at different distances as the beams propagate from left to right. Credit: P. Panagiotopoulos, et al. ©2013 Macmillan Publishers Limited This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
(Phys.org)—It was an interesting week for physics as a team of researchers with the University of California and the University of Tokyo proposed a new definition of time crystals—then proved such things don’t exist—theory had suggested a system that could move despite not having enough energy to do so. Also, a team at Ecole Normale Supérieure in France demonstrated a way to control the quantum properties of light by using microwave photons to probe a superconducting circuit. And researchers working for the Department of Energy used neutrons to find the “missing” magnetism of plutonium—confirming a long held theory. Boeing patent puts focus on laser-powered propulsion system (Update) It was also an interesting week for space exploration, mostly notably regarding reports describing findings by NASA’s New Horizon spacecraft as it approaches Pluto—first, as the craft moved closer, new geological features began to appear. Then, after getting even closer to the dwarf planet, researchers noted a heart-shaped feature on the surface—though they still do not know what it is. Such news highlights a problem developing within NASA and other space research groups: How will we know when we have found extraterrestrial life? Phys.org spoke to Terence Kee, President of the Astrobiology Society of Britain to gain some insight. In related news, a new Boeing patent put focus on laser-powered propulsion systems for airplanes, and potentially for spacecraft as well. The idea appears to involve firing a laser at a piece of radioactive material, setting off a small fusion reaction. Boeing has not commented publicly on the patent or idea.In other news, a team of researchers at Pennsylvania State University College of Medicine wondered: Can four fish oil pills a day keep the doctor away? They believe the answer is yes, at least for older people who take the pills for at least three months. Also, somewhat ominously, researchers with NASA’s Jet Propulsion Laboratory working on a new study found that heat is being stored beneath the ocean surface. That helps to explain where all the excess heat due to greenhouse gases has been going, but it also poses the question of what happens when the saturation point is reached.And finally, if you are one of the millions of people who suffer with some type of chronic pain, good news may be coming soon as a team of researchers at the University of California has found the key mechanism that causes neuropathic pain—they believe the discovery will open the door to new treatments that will finally alleviate suffering from such ailments as trauma, diabetes, MS, shingles and a host of other conditions. © 2015 Phys.org Explore further This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: Best of Last Week – New definition of time crystals, new images of Pluto and the mechanism that causes neuropathic pain (2015, July 13) retrieved 18 August 2019 from https://phys.org/news/2015-07-week-definition-crystals-images-pluto.html Zeno cat. A Zeno cat refers to non-classical states of light created by shining a cavity on resonance while it is forbidden to access a given energy level. The name originates from the Zeno effect, which can similarly prevent an energy level from being occupied by the sole fact of measuring its occupation frequently. The cat comes from the similarity of such a state with a Schrödinger cat state of light: a superposition between two classical states of light. The Zeno cat figure corresponds to the study’s experimental design. Credit: Benjamin Huard.
Explore further Since it was first developed three years ago and marketed, artists and manufacturers have shown interest in using the coating to create unique-looking products—a watch from Contemporaine du Temps, for example, designed by British artist, Anish Kapoor, features Vantablack on its dial and minute hand—it adds a degree of depth to the watch that other watches do not have.Representatives for Nanosystems have told the press that they believe that Vantablack could also be used to improve the performance of cameras and sensors—the only drawback is that the coating is still too delicate for use in commercial applications, though it has been used on some star-tracking satellites. Vantablack is made by chemically growing a network of carbon nanotubes (each of them is just 20 nanometers in diameter and approximately 14 microns to 50 microns in length) in a high-temperature chamber, creating a forest of sorts on a base such as aluminum—the nanotubes are so small and dense that the company reports that over a billion of them exist on a 0.1 in square patch. The material is then applied as a coating to another object—light hitting the coating is absorbed because it is bounced around between the nanotubes instead of being reflected back. Such materials have an eerie look, as they appear to be missing features normally seen in other black materials. The result is striking—coated objects appear is if they have been photoshopped to remove all traces of contours and other features. It is only by changing the angle of objects coated with the material that features are visible.Nanosystems has also reportedly developed a spray version of Vantablack (Vantablack S-VIS.) which should make the coating more accessible to anyone who wants to use it, though it is not quite as black. Credit: Surrey Nanosystems (Phys.org)—U.K.-based Surrey Nanosystems has announced that it has improved on the original Vertically Aligned Nanotube Array BLACK (Vantablack coating) which the company claimed to be the blackest material ever made. The original Vantablack was found to absorb 99.96 percent of visible (and ultraviolet and infrared) light—the new Vantablack is darker—so much so that it cannot be measured by a spectrometer. Citation: New version of Vantablack coating even blacker than original (2017, April 11) retrieved 18 August 2019 from https://phys.org/news/2017-04-version-vantablack-coating-blacker.html © 2017 Phys.org Credit: Surrey Nanosystems Surrey NanoSystems has “super black” material This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
© 2018 Phys.org Physicists have designed a 3-D quantum memory that addresses the tradeoff between achieving long storage times and fast readout times, while at the same time maintaining a compact form. The new memory has potential applications in quantum computing, quantum communication, and other technologies. Journal information: Applied Physics Letters Citation: Compact 3-D quantum memory addresses long-standing tradeoff (2018, June 4) retrieved 18 August 2019 from https://phys.org/news/2018-06-compact-d-quantum-memory-long-standing.html Record-breaking efficiency for secure quantum memory storage Explore further More information: Edwar Xie, et al. “Compact 3-D quantum memory.” Applied Physics Letters. DOI: 10.1063/1.5029514 The physicists, Edwar Xie and coauthors at the Walther-Meissner-Institut, Technical University of Munich, and Nanosystems Initiative Munich (NIM), Germany, have published a paper on the new 3-D quantum memory in a recent issue of Applied Physics Letters.”Since quantum information is very fragile, it needs to be processed fast or preserved in a suitable storage. These two requirements are typically conflicting,” Xie told Phys.org. “The greatest significance of our work is that it shows how to build a device with fast access to stored quantum information, enabling fast processing, combined with a long storage time.”One of the greatest challenges facing any kind of quantum technology is enhancing the qubit lifetime, and when it comes to quantum memories, 3-D devices offer the longest coherence times, up to a few milliseconds. In these memories, qubits are stored in 3-D microwave waveguide cavities, whose slow decay times enable long qubit storage times. However, a tradeoff occurs in these devices, since fast readout times require the cavity decay to be fast.Previously, researchers have addressed this tradeoff in various ways, such as by physically separating the storage and readout units. However, with separate units the devices become relatively large and bulky compared to 2-D memories, causing problems for scalability.In order to simultaneously achieve long storage times, fast readout times, and a small footprint, in the new study the researchers made use of the multimode structure of 3-D cavities. In this approach, the researchers used antennas to couple a qubit to two distinct modes of a single 3-D microwave cavity, which is much more compact than using two entirely separate units. They engineered the cavity so that the memory mode has a quality factor that is 100 times larger than that of the readout mode, which leads to slow decay for the memory mode and fast decay for the readout mode.As a result of this coupling, the researchers demonstrated that the qubit state can be read out on a timescale that is 100 times shorter than the storage time. Further, simulations showed that more accurate antenna positioning could extend the ratio between readout and storage time to 25,000. This value would significantly outperform the current highest reported ratio of 7300 for quantum memories with cylindrical 3-D cavities.In the future, the researchers plan to make further improvements to the memory, such as scaling up by adding more qubits, coupling the qubit to higher cavity modes, and enabling the memory to store cat states (a superposition of two macroscopic states), which has potential applications in continuous variable quantum computing. “One potential application of this compact 3-D quantum memory lies in the field of analog quantum simulation, where an engineered quantum circuit, such as a qubit, mimics an atom,” Xie said. “Due to its compact size and relaxed requirements of cabling, our 3-D quantum memory platform is specifically suitable for building chains of artificial atoms for the simulation of molecules. Here, one cell of the chain consists of a single 3-D cavity with one qubit, a storage mode for intermediate information storage and a readout mode for fast information retrieval. The coupling to the neighboring cell can be achieved with another qubit.” (a) Photograph of the 3D quantum memory and (b) optical micrograph of a qubit. Credit: Xie et al. ©2018 American Institute of Physics This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
LEFT: Simulation surface configuration. Illustration of the 3D simulation repeat unit, with 2D cross section showing labeled structural parameters. RIGHT: Quantification and mechanisms leading to the CAH (contact angle hysteresis) for reentrant and doubly reentrant geometries at zero applied pressure. (A) (i) CAH dependence on both the area fraction Fr and total cap height Dr. Symbols indicate the depinning mechanism upon receding, with purple diamonds indicating a hybrid mechanism. (ii and iii) Comparison of the bridge-, edge-, and lip-depinning receding models (solid lines, color-coded) against the simulated θr (data points); examples shown with varying Fr at fixed Dr = 0.05 and 0.35. The ±1° error bars in the simulation data are too small to be seen. (B) 3D visualization of the advancing liquid-vapor interface (shown in blue); the advancing direction is indicated by a black arrow. Black and red lines indicate the center and edge 2D cross sections that are also presented (right). (C) (i to iv) Visualizations of the major four receding mechanisms. The receding direction is indicated by black arrows. Credit: Science Advances, doi: 10.1126/sciadv.aav7328 , Proceedings of the National Academy of Sciences Journal information: Science Advances In this way, the scientists developed highly versatile computational techniques to study any mesoscopically structured surface in contact with multiple fluid phases. The multifaceted optimization strategy can be further improved for reliability and scalability to couple with recent advances in fabrication including 3-D printing and lithographic methods to efficiently design real-world superomniphobic surfaces. In materials science, surfaces that strongly repel low surface tension liquids are classified ‘superoleophobic,” while high surface tension liquid repellants are ‘superhydrophobic’ and surfaces that display both characteristics are ‘superomniphobic.” Superomniphobic surfaces are at the frontiers of surface design for a vast array of applications. In a recent study, J. R. Panter and co-workers at the Department of Physics and Procter and Gamble Co. in the U.K. and the U.S. developed computational methods to systematically develop three key surface wetting properties. These included contact angle hysteresis, critical pressure and a minimum energy wetting barrier. In the study, the scientists developed quantitative models and corrected inaccurate assumptions within existing models. When studying the third parameter on minimum energy transition mechanisms, the scientists identified three failure mechanisms. For instance, a surface design failure can be initiated through a broad range of additional perturbations including flow, vibration, evaporation, condensation, droplet impact, changing electrical and magnetic fields or thermal fluctuations at the nanoscale. In real-world applications, failure could be initiated by a combination of perturbations. To fabricate a texture resistant to failure, Panter et al. therefore combined the maximum energy pathway (MEP) to account for a worst case scenario of combined failures. They identified three transition pathways as (1) base contact (BC), (2) pillar contact (PC) and (3) cap contact (CC), then quantified each barrier across the structural parameter space. Thereafter, they assessed the likeliest mechanism of energy transition for a given surface geometry. The scientists then conducted simultaneous optimization of the identified structural features to maximize critical pressure, minimize the energy barrier and maximize the CAH. For this, they performed optimal design of two membranes for applications on water purification and digital microfluidics. Panter et al. also showed that a genetic algorithm could be used to efficiently locate the optimum design in the parameter space and design more complex structures for special wettability applications. Critical pressure analysis for reentrant and doubly reentrant geometries. (A) Contour plots of ΔPc variation with Fr and Hr for reentrant (i) and doubly reentrant (ii) geometries. Data points mark the critical height at which the failure mechanism switches from Base Failure (BF) to Depinned Cap Failure (DCF) or Pinned Cap Failure (PCF), and error bars indicate the uncertainty in this height due to the diffuse interface width. Solid and dashed white lines show the critical height based on the capillary model and 2D model, respectively. (B) Model fits to ΔPc of the Cap Failure mechanisms at Hr = 0.25 for reentrant (i) and doubly reentrant (ii) geometries. (C to E) The three failure mechanisms shown in 3D, with associated diagonal cross sections. Critical pressure liquid morphologies are shown in blue, the vapor phase is shown in white, and the interface is indicated with a black solid line. Red regions show how the unstable meniscus evolves upon increasing ΔP above ΔPc. (D and E) Under-cap views, highlighting the shapes of the contact lines at the critical pressure. (F) Details of the 3D horizontal (3DD) and 3D diagonal (3DH) capillary bridge models used, showing the inner and outer circumferences (blue) against the system configuration. The 3D illustration compares the simulated liquid-vapor interface (light blue) to the horizontal capillary model (dark blue). Credit: Science Advances, doi: 10.1126/sciadv.aav7328 Explore further Simultaneous optimization of the three wetting properties for membrane distillation and digital microfluidics applications. (A) (i) 3D contour plot of the membrane distillation scoring function at fixed Hr = 0.3, Ar = 0.05, and tr = 0.05. Each surface is a surface of constant score. (ii) A 2D slice of the 3D contour plot at the optimal Lr = 0.17. Square data points show the initial (white), second (light gray), fifth (dark gray), and final (black) generations of the genetic algorithm, projected onto the 2D plane. (B) Scoring function for the digital microfluidics application, projected onto the Hr = 0.3 plane at fixed B = 100 μm, also showing the successive generations of the genetic algorithm population. Credit: Science Advances, doi: 10.1126/sciadv.aav7328 Making a splash is all in the angle Video shows the pillar contact (PC) mechanism for a doubly reentrant geometry at θ° = 60° a surface property identified in the study. Credit: Science Advances, doi: 10.1126/sciadv.aav7328 Panter et al. combined these analyses simultaneously to demonstrate the power of the strategy to optimize structures for applications in membrane distillation and digital microfluidics. By antagonistically coupling the wetting properties, the scientists implemented a multifaceted approach to optimally design superomniphobic surfaces. Using genetic algorithms, they facilitated efficient optimization for speedups of up to 10,000 times. The results of the study are now published on Science Advances. Superomniphobic surfaces have physical micro- and nanotextures that allow low-surface-tension liquids (oils and alcohols) to remain suspended on a vapor-filled surface structure. This liquid-shedding ability can promote efficient droplet mobility with low viscous drag , with transformative potential across a broad range of applications. These include sustainable technologies for water purification, antimicrobial strategies in biomedicine, anti-fingerprint coating techniques, reducing food waste and versatile biochemical technologies, at the global scale. Recent breakthroughs in microfabrication have allowed the formation of complex structures at the micrometer scale resolution, including three-dimensional (3-D) printing technology, fluidization of polymer micropillars and lithographic methods. Despite these highly versatile techniques, materials scientists and physicists still seek to understand how to precisely design surface structures for optimal performance in real-world applications. A successful omniphobic design must demonstrate three key wetting properties to include (1) a low contact angle for maximum liquid mobility, (2) high critical pressure for stability of the superoleophobic state, and (3) a high energetic barrier to failure. Due to complexities of surface design, uniting computational and experimental studies can be expensive and time-consuming to understand this basis. In the present work, Panter et al. overcame the challenges of designing superomniphobic wetting properties by first designing computational strategies to understand the effect that structural parameters had on the three defined criteria. To illustrate the importance of multifaceted optimization they used two relevant examples of water purification via membrane distillation and droplet-based digital microfluidics. The scientists developed a genetic algorithm to efficiently perform simultaneous optimizations with speedup to 10,000 times. This versatile approach can be coupled to recent innovations in complex surface microfabrication techniques to offer a transformative approach to surface design. The scientists first simulated the liquid vapor interface advancing and receding along a single row of surface structures to obtain their respective contact angles and contact angle hysteresis (CAH, i.e., the difference between advancing and receding contact angles). They arranged the variable dimensions in a square array and observed the hysteresis to be identical for both reentrant and doubly reentrant geometries (geometries with very low liquid-solid contact fraction). Using the simulation, the scientists observed four dominant receding mechanisms to describe and model them in the present work. Thereafter, using the new models Panter et al. qualitatively tested the receding models proposed in previous studies to verify their accuracy. They analyzed the energetic changes to obtain the angle at which receding became energetically favorable to form the optimal receding angle. Unlike simulations of CAH, the second parameter of interest on critical pressure was sensitive to the reentrant or double reentrant surface geometry. The scientists observed three failure mechanisms in the critical pressure study and quantified them as a function of the structural parameters. When they compared quantification in the present work with simulation data, they detected prevailing and widely used critical pressure models introduced in previous studies to be considerably oversimplified. For instance, poor description of the liquid-vapor interface morphology prompted manufactured structures to be many times smaller and mechanically weaker than necessary. By developing a more sophisticated model in the present work, Panter et al. achieved both quantitative accuracy of the critical pressures and successfully modeled the desired complex interfacial morphologies. More information: J. R. Panter et al. Multifaceted design optimization for superomniphobic surfaces, Science Advances (2019). DOI: 10.1126/sciadv.aav7328 Arun K Kota et al. The design and applications of superomniphobic surfaces, NPG Asia Materials (2014). DOI: 10.1038/am.2014.34A. Tuteja et al. Robust omniphobic surfaces, Proceedings of the National Academy of Sciences (2008). DOI: 10.1073/pnas.0804872105 A. Tuteja et al. Designing Superoleophobic Surfaces, Science (2007). DOI: 10.1126/science.1148326 , Science Demonstrating a failure mechanism identified in the study, video shows the base contact (BC) mechanism for a doubly reentrant geometry at θ° = 60°. Credit: Science Advances, doi: 10.1126/sciadv.aav7328 © 2019 Science X Network Citation: Multifaceted design optimization for superomniphobic surfaces (2019, June 28) retrieved 18 August 2019 from https://phys.org/news/2019-06-multifaceted-optimization-superomniphobic-surfaces.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
The book was released by Szilveszter Bus, Ambassador-Designate of Hungary. The launch was followed by an illustrated lecture, Amrita Sher-Gil, Paris, and the Bloomsbury Group, by an art historian Giles Tillotson and a special screening of the film, Amrita Sher-Gil: The Bridge Builder, directed by Ebrahim Alkazi.The book talks about Amrita Sher-Gil’s journey between the polarities when she remained unacknowledged during her life and considered an icon post her death. Did the Ajanta caves and Gauguin influence Amrita’s works? How was she as a person and as an artist? Was her work in India indeed of unequal quality as often considered to be? In this collection, Karl Khandalavala, G H R Tillotson, K G Subramanyan, and N Iqbal Singh, among others, ponder these and other aspects of Amrita’s short but impactful life dedicated to art. Also Read – ‘Playing Jojo was emotionally exhausting’With Charles Fábri’s fictional account of the travails of a young artist in Lahore in the 1940s carrying an unmistakable resemblance with the influential and avant-garde artist, the volume also includes a piece by Amrita on her evolution as an artist. Accompanied by rare black and white and colour visuals, this book brings together modern and contemporary critiques as well as early writings by past masters that have largely remained inaccessible until now.
Kolkata: Taking a tough stand against infighting, the Trinamool Congress on Tuesday removed the chairman and vice-chairman of North Dum Dum municipality and announced the names of Subodh Chakraborty as chairman and Lopamudra Dutta Chowdhury as vice-chairman of the civic body.The decision was taken after a high-level meeting at the chamber of state Food minister Jyotipriya Mallick who also happens to be the TMC president of the North 24-Parganas. Senior Trinamool Congress leaders like Saugata Roy, Chandrima Bhattacharjee, Nirmal Ghosh and most importantly 25 councillors of the municipality were also present in the meeting. Also Read – Heavy rain hits traffic, flights”We have removed the chairman and vice-chairman and have appointed new ones after we reached a consensus in the meeting. The parliamentary party of the municipality will hold a meeting every 15 days to keep a stock of the progress of work and at the same time a monitoring committee that has been formed will also hold meetings in presence of senior leaders to keep an eye on the functioning ” Mallick said.It may be mentioned that factional feuds within the TMC had reached its pinnacle in North Dum Dum on May 24 when the vice-chairman of the TMC-run North Dum Dum municipality was assaulted at his office by two contractors allegedly close to chairman Kalyan Kar. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedThe ruckus inside spilled on to the streets as vice-chairman Nazimul Haq’s supporters blocked roads and railway tracks and damaged police vehicles, bringing traffic in Birati-Nimta area to a halt. Even MP Saugata Roy was mobbed by the protesters when he reached the spot to pacify the crowd.The party had formed a committee under the leadership of Roy to address the issue of internal infighting. The committee had recommended the removal of both the chairman and the vice-chairman for such action which they felt was not commensurate with the party line. The recommendation was ratified in Tuesday’s meeting.
The next time a hangover hits you hard the morning after a late-night party, look in the mirror to see if your hair is turning white or your hairline is receding.Yes, age is a major factor in the way drinking affects you. Worsening impact of hangovers are a reminder that drinking in moderation would be a better idea, say health experts.“The capacity of our liver to cope with alcohol reduces with age. The alcohol metabolising enzyme reduces and the body fat increases reducing muscle mass, thus increasing the effect of alcohol,” said Dr Rahul Tambe, general physician from Nanavati Super Specialty Hospital in Mumbai in an email. Also Read – ‘Playing Jojo was emotionally exhausting’“Elderly people are often on multiple medication which interferes with alcohol metabolism. Losing weight causes reduced distribution of alcohol in body causing greater intoxication and hangover,” he added.According to Dr Yogesh Batra, senior consultant (gastroenterology) at BLK Super Specialty Hospital in New Delhi, with age, there is an accumulation of substances like acetaldehyde in the liver which are the by-products of alcohol metabolism and are one of the “incriminating agents” responsible for hangovers. Also Read – Leslie doing new comedy special with Netflix“There is brain degeneration with age and the toxic products tend to hit the brain harder. There is a tendency towards dehydration as the ageing population tends to drink less water which leads to hangovers,” Dr Batra said. Hangover or veisalgia is usually experienced after an alcoholic over-indulgence. The symptoms experienced range from a simple headache to severe nausea, vomiting, giddiness, fatigue and sweating. In some people, it can even lead to anxiety or panic attacks. Severity of hangover depends on amount of alcohol intake, frequency of heavy drinking and food intake. Is there a cure for hangover? “Eat more before and after the alcoholic consumption. Besides eating, drinking loads of fluids will also help. Lime water is the best fluid which can be consumed before and after the alcoholic consumption,” advises Dr Deepak Verma, general physician from Columbia Asia Hospital in Ghaziabad. Alcohol consumption can irritate the stomach lining, leading to gastritis. So, food and fluids taken before and after alcoholic consumption help to reduce the gastric irritation, the experts note.Hangover is best dealt with adequate sleep or rest, plenty of liquids and food. “Losing weight leads to even worse hangovers. Since the effective alcohol concentration in the body is going to be more hence those who lose weight should reduce drinking,” says Dr Batra. In the end, preventing a hangover is easy —drink in moderation, space out your drinks, have plenty of water and eat. But then who doesn’t know this? | 0.827384 | 3.075839 |
Two white dwarfs circle around one other, locked in a fatal tango. With an intimate orbit and a hefty combined mass, the pair is ultimately destined to collide, merge, and erupt in a titanic explosion: a Type Ia supernova.
Or so goes the theory behind the infamous “standard candles” of cosmology.
Now, in a paper published in today’s issue of Nature, a team of astronomers have announced observational support for such an arrangement – two massive white dwarf stars that appear to be on track for a very explosive demise.
The astronomers were originally studying variations in planetary nebulae, the glowing clouds of gas that red giant stars throw off as they fizzle into white dwarfs. One of their targets was the planetary nebula Henize 2-428, an oddly lopsided specimen that, the team believed, owed its shape to the existence of two central stars, rather than one. After observing the nebula with the ESO’s Very Large Telescope, the astronomers concluded that they were correct – Henize 2-428 did, in fact, have a binary star system at its heart.
“Further observations made with telescopes in the Canary Islands allowed us to determine the orbit of the two stars and deduce both the masses of the two stars and their separation,” said Romano Corradi, a member of the team.
And that is where things get juicy.
In fact, the two stars are whipping around each other once every 4.2 hours, implying a narrow separation that is shrinking with each orbit. Moreover, the system has a combined heft of 1.76 solar masses – larger, by any count, than the restrictive Chandrasekhar limit, the maximum ~1.4 solar masses that a white dwarf can withstand before it detonates. Based on the team’s calculations, Henize 2-428 is likely to be the site of a type Ia supernova within the next 700 million years.
“Until now, the formation of supernovae Type Ia by the merging of two white dwarfs was purely theoretical,” explained David Jones, another of the paper’s coauthors. “The pair of stars in Henize 2-428 is the real thing!”
Check out this simulation, courtesy of the ESO, for a closer look at the fate of the dynamic duo:
Astronomers should be able to use the stars of Henize 2-428 to test and refine their models of type Ia supernovae – essential tools that, as lead author Miguel Santander-García emphasized, “are widely used to measure astronomical distances and were key to the discovery that the expansion of the Universe is accelerating due to dark energy.” This system may also enhance scientists’ understanding of the precursors of other irregular planetary nebulae and supernova remnants.
The team’s work was published in the February 9 issue of Nature. A copy of the paper is available here. | 0.949274 | 3.941145 |
Geography of Mars
Article written by Jim Secosky. Jim is a retired science teacher who has used the Hubble Space Telescope, the Mars Global Surveyor, and HiRISE.
This article will describe the geography of Mars, starting with large features and then get more specific. Many maps will display groups of features and all can be copied and used without permission. Although there are many good maps of Martian features, most are under some sort of copyright protection.
North and South
One of the most significant aspects of Mars is the vast difference between the northern and southern hemispheres. Much of the north is smooth and of low elevation. In contrast, the southern half of the planet is rough with great numbers of craters (indicating an old age). The south is also much higher in altitude (between 1-3 km higher). The boundary between the Southern and the Northern hemispheres is called the Martian dichotomy. Although several ideas have been advanced to explain these differences, at present it is thought the northern hemisphere was struck on a low angle by an asteroid early in its history.
East and West
The Eastern hemisphere of Mars holds a small collection of volcanoes, Hellas Planitia, (a large impact crater) and a dark area that was the first feature noted on the surface by early astronomers. Studies suggest that the heat from the impact that created the Hellas Basin caused the entire surface of Mars to heat hundreds of degrees. In addition, the surface was covered with 70 meters of molted rock which fell from the sky. For a time an atmosphere of gaseous rock existed. This rock atmosphere would have been 10 times as thick as the Earth's atmosphere. In a few days, the rock would have condensed out and covered the whole planet with an additional 10 m of molten rock.
The HiRISE instrument onboard the Mars Reconnaissance Orbiter has discovered a strange feature on the floor of Hellas Planitia. Called "Honeycomb Terrain," it may be caused by great masses of buried water ice moving upward. However, there are several other hypothesizes for its creation being considered.
There is a big contrast between the Western and Eastern hemisphere of Mars. The Western hemisphere has the great Valles Marineris, the Grand Canyon of Mars. It could stretch nearly across the continental United States. At its western end is a large group of intersecting canyons, called Noctis Labyrinthus. This hemisphere also hosts a region known as Tharsis. Tharsis is home to the largest volcanoes on Mars and in the solar system. The southern part contains Argyre Planitia, a large impact basin that probably contained a lake. The western hemisphere also contains many outflow channels, such as Ares Vallis, Ravi Vallis, Mawrth Vallis, and Kasei Valles in which giant flows of water went roaring though. Calculations indicate that the amount of water required to erode such channels at least equals and most probably exceeds by several orders of magnitude the present discharges of the largest terrestrial rivers. These Martian floods would be comparable to the largest floods known to have ever occurred on Earth (the ones that cut the Channeled Scablands in North America).
Mars is a land of great volcanoes. Tharsis contains the largest volcano in the solar system, along with several that are about as tall as the Earth’s tallest mountains. In addition, many small ones may actually be mostly covered by ash. We may be seeing only their tips. Tharsis covers almost 25 % of the surface of the planet. Elysium volcanic province, another smaller group of volcanoes, sits in the Eastern hemisphere; the biggest of the three is called Elysium Mons. Apollinaris Mons is near the landing site for the Spirit Rover. This volcano may have covered over expected lake deposits in Gusev Crater. The first feature to be drawn on early maps of Mars was Syrtis Major. This dark feature is volcanic by nature with two caldera: Meroe Patera and Nili Patera. Studies involving the regional gravity field suggest a solidified magma chamber exists beneath its surface. Syrtis Major is of interest to geologists because dacite and granite have been detected there from orbiting spacecraft. Dacites and granites are very common on Earth but rare on Mars. Lava sometimes forms lava tunnels. These are places in which a hard cap forms on top of a flow while the rest of the liquid lava has moved away. These tunnels can be quite large. Many have suggested that future colonists can use these tunnels for their shelters where there would be protection from radiation and meteorites, and where there would be a more constant temperature. Some pictures taken with HiRISE seem to show pits that may lead into these hollowed out places.
Several old, eroded volcanoes exist near to the great impact crater Hellas Planitia. Some researchers have suggested that the location of the highland paterae around Hellas is due to deep-seated fractures caused by the impact that provided channels for magma to rise to the surface.
Because the surface of Mars is so old, billions of years in some areas, it contains many impact craters. Basically, the more craters the older the surface. The older, southern highlands contain far more craters than the North. Craters can help us sample material under the surface because an impact event brings material from deep underground. Moreover, some material from the impactor could be gathered by automated machines in the future for use by the colonists. Our rovers have already photographed and examined meteorites sitting on Mars. Meteoritic material is more likely to come from small craters, as in large impacts the impacting body is usually vaporized.
Low plains on Mars are called “Planitia.” Many of these were formed by impact events, especially Chryse, Utopia, Isidis, Argyre, and Hellas. Hellas Planitia is the deepest area on the planet. Many craters are believed to have once held lakes, including Argyre Planitia and Hellas Planitia in the South. High resolution views of many crater show that they have almost completely filled with ice which is visible as many concentric ridges. Craters begin with a bowl shape. After millions of years of collecting snow, they appear flat and shallow. Researchers have named the material “ Concentric Crater Fill .”
The craters Milankovic, Lomonosov, Kunowsky, Lyot, and Mie are in the North and are easy to spot because there are very few features near them. The Viking 2 spacecraft landed near Mie Crater. Mariner Crater was discovered and named after the Mariner 4 spacecraft. Mariner 4’s image of Mariner Crater was the best picture returned by the Mariner 4 flyby. Nicholson and Schiaparelli Craters sit almost directly on the equator.
South Pole Region
This region is covered in the Mare Australe quadrangle. The ice cap at the South Pole is much smaller than the one in the North. Parts of Mare Australe display pits that make the surface look like Swiss cheese. These pits are in a 1-10 meter thick layer of dry ice that is sitting on a much larger water ice cap.
North Pole Region
The ice cap in the north is far larger than the one in the south. It contains a large pattern of spiral-shaped troughs. In the troughs many layers are visible in high resolution photos. The layers result from climate changes. At times the atmosphere contains more dust, consequently darker layers are formed. Sometimes thicker deposits of ice are deposited, making thicker layers. From observations with the Shallow Radar instrument (SHARAD), researchers determined that the total volume of water ice in the cap is 821,000 cubic kilometers. That is equal to 30% of the Earth's Greenland ice sheet, or enough to cover the surface of Mars to a depth of 5.6 meters
Origin of Names
Many of the names for features on Mars are based on old classical names. Most of these names came from the names given by the astronomer G. V.Schiaparelli. A more detailed discussion of the origin of Martian nomenclature can be found in How are features on Mars Named?.
One way of locating places on Mars is with quadrangles. The surface of Mars is divided into 30 areas. Each quadrangle has a number and a name. Detailed descriptions and many images from each quadrangle can be found on the Quadrangles pages.
Mission Landing Sites
We have attempted to land on the Martian surface many times. There have been many failures. However, in recent years there have been some missions that have been highly successful. The Spirit and Opportunity Rovers were only expected to last for 3 months. Both lasted for many years. As of this writing (April 2018) Opportunity is still examining the planet. These twin rovers landed in January of 2004. It might go much longer, but the government is eager to shut them down. Curiosity Rover has sent back some great pictures and science. Some believe it will be working until people land on the planet.
The following map shows the landing sites and the dates of successful and unsuccessful missions.
Locations of ice
Locations of near surface Ice
Data gathered from spacecraft over many years has enable scientists to construct a map showing where ice may be found under a thin cover of sand. Places where ice is found under perhaps just centimeters of sand would be idea for future colonists. They could send robotic machines to gather ice which could provide water for settlements. Places where water-ice is found under a thin soli cover can be determined because of the properties of ice. If ice abundant ice is found just under the surface, the region will take longer to heat up in the spring and longer to cool down in the fall. Thermal inertia measurements gathered with the Mars Global Surveyor were used to generate a map of underground ice.
A later study used two heat-sensitive instruments: MRO's Mars Climate Sounder and the Thermal Emission Imaging System (THEMIS) camera on Mars Odyssey to produce similar results to those using thermal inertia measurements from the Mars Global Surveyor.
Locations of ice
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- Nimmo; et al. (2008). "Implications of an impact origin for the Martian hemispheric dichotomy". Nature. 453 (7199): 1220–1223.
- Carr, Michael H. (2006). The Surface of Mars. Cambridge University Press. ISBN 978-0-521-87201-0.
- Bernhardt, H.; et al. (2016). "The honeycomb terrain on the Hellas basin floor, mars: a case for salt or ice diapirism: hellas honeycombs as salt/ice diapirs". J. Geophys. Res. 121: 714–738.
- Weiss, D., J. Head. 2017. HYDROLOGY OF THE HELLAS BASIN AND THE EARLY MARS CLIMATE: WAS THE HONEYCOMB TERRAIN FORMED BY SALT OR ICE DIAPIRISM? Lunar and Planetary Science XLVIII. 1060.pdf
- Weiss, D.; Head, J. (2017). "Salt or ice diapirism origin for the honeycomb terrain in Hellas basin, Mars?: Implications for the early martian climate". Icarus. 284: 249–263.
- Parker, T.; et al. 2000. Argyre Planitia and the Mars global hydrological cycle . LPSC. XXXI: 2033.
- Dohm, J.; Hare, T.; Robbins, S.; Williams, J.-P.; Soare, R.; El-Maarry, M.; Conway, S.; Buczkowski, D.; Kargel, J.; Banks, M.; Fairén, A.; Schulze-Makuch, D.; Komatsu, G.; Miyamoto, H.; Anderson, R.; Davila, A.; Mahaney, W.; Fink, W.; Cleaves, H.; Yan, J.; Hynek, B.; Maruyama, S. 201). Geological and hydrological histories of the Argyre province, Mars. Icarus. 253: 66–98.
- Baker, V. 1982. The Channels of Mars. Austin: Texas University Press.
- Carr,M.H. (1979). "Formation of Martian flood features by release of water from confined aquifers". J. Geophys. Res., 84, 2995-3007.
- Williams, R., Phillips, R., and Malin, M. 2000. Flow rates and duration within Kasei Vallis, Mars: Implications for the formation of a Martian ocean. Geophys. Res. Lett., 27, 1073-6.
- Robinson, M., and Takana, K. 1990. Magnitude of a catastrophic flood event in Kasei Vallis, Mars. Geology, 18, 902-5.
- Whitford-Stark, J. 1982. Tharsis Volcanoes: Separation Distances, Relative Ages, Sizes, Morphologies, and Depths of Burial. J. Geophys. Res. 87: 9829–9838.
- Solomon, Sean C.; Head, James W. (1982). "Evolution of the Tharsis Province of Mars: The Importance of Heterogeneous Lithospheric Thickness and Volcanic Construction". J. Geophys. Res. 87 (B12): 9755–9774.
- Kiefer, W. |year=2002 |title=Under the volcano: gravity evidence for an extinct magma chamber beneath Syrtis Major, Mars |work=American Geophysical Union, Fall Meeting 2002 |at=abstract #P71B-0463
- Peterson, J. 1978. Volcanism in the Noachis-Hellas region of Mars, 2. Lunar and Planetary Science. IX: 3411–3432.
- Williams, D.; et al. 2009. The Circum-Hellas volcanic province, Mars: Overview. Planetary and Space Science. 57: 895–916.
- Rodriguez, J.; K. Tanaka. 2006. Sisyphi Montes and southwest Hellas Paterae: possible impact, cryotectonic, volcanic, and mantle tectonic processes along Hellas Basin rings. Fourth Mars Polar Science Conference. p. 8066.
- Cabrol, N. and E. Grin (eds.). 2010. Lakes on Mars. Elsevier. NY.
- Voelker, M., et al. 2016. DISTRIBUTION AND EVOLUTION OF LACUSTRINE AND FLUVIAL FEATURES IN HELLAS PLANITIA, MARS, BASED ON PRELIMINARY RESULTS OF GRID-MAPPING. 47th Lunar and Planetary Science Conference (2016) 1228.pdf.
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- Thomas, P., W. Calvin, B. Cantor, R. Haberle, P. James, S. Lee. 2016. Mass balance of Mars’ residual south polar cap from CTX images and other data Icarus: 268, 118–130 http://doi.org/10.1016/j.icarus.2015.12.038
- Buhler, Peter, Andrew Ingersoll, Bethany Ehlmann, Caleb Fassett, James Head. 2017. How the martian residual south polar cap develops quasi-circular and heart-shaped pits, troughs, and moats. Icarus: 286, 69-9.
- Sylvain Piqueux, Jennifer Buz, Christopher S. Edwards, Joshua L. Bandfield, Armin Kleinböhl, David M. Kass, Paul O. Hayne. Widespread Shallow Water Ice on Mars at High and Mid Latitudes. Geophysical Research Letters, 2019; DOI: 10.1029/2019GL083947
- Piqeux, S. et al. 2019. WIDESPREAD SHALLOW WATER ICE ON MARS AT HIGH AND MID LATITUDES. Ninth International Conference on Mars 2019 (LPI Contrib. No. 2089). 6027.pdf.
- Baker, V.R. (1982). The Channels of Mars. Austin: Texas University Press.
- Carr,M.H. (1979). "Formation of Martian flood features by release of water from confined aquifers". J. Geophys. Res., 84, 2995-3007.
- Carr, M.H. (2006), The Surface of Mars. Cambridge Planetary Science Series, Cambridge University Press.
- Robinson, M.S., and Takana, K.L. (1990), "Magnitude of a catastrophic flood event in Kasei Vallis, Mars". Geology, 18, 902-5.
- Diacria quadrangle
- Hellas Planitia
- High Resolution Imaging Science Experiment (HiRISE)
- How are features on Mars Named?
- How living on Mars will be different than living on Earth
- Lunae Palus quadrangle
- Oxia Palus quadrangle
- Valles Marineris | 0.908921 | 3.911573 |
Face-On Spiral Galaxy Messier 74
Messier 74 appears in this image as the perfect archetype of a great design, face-on spiral galaxy, composed by a bright central core surrounded by faint and diffuse spiral arms. Spiral galaxies have flat shapes similar to dishes, causing a varying appearance depending on their inclination with respect to our line of sight. Therefore, when we look at an edge-on spiral galaxy, the central bulge outstands spheroidal in shape, while the spiral arms apparently display a “line” design. An archetype of edge-on spiral galaxy is NGC 891. An excellent example of spiral galaxy seen under an intermediate angle can be seen in the image of NGC 7331 offered by Calar Alto Observatory in a previous photo release.
The study of all known spiral galaxies has shown that stars on the outer parts of these systems orbit around the centre faster than predicted by Kepler laws, just as if there were more matter than deduced “weighting” the luminous objects (stars) seen in these island-universes. This unobserved matter, with so clear gravitational effects, is what astronomers called dark matter, an exotic and unknown kind of substance that does not emit light, and that constitutes one of the most intriguing challenges for modern astronomy.
Face-on spiral galaxies like M 74 are of high interest for researchers, as they let us look into them in high detail. Such overhead images are of interest to know how the population and behaviour of stars changes along the radial distance from the centre. As this picture clearly shows, the outer parts are bluer than the inner parts, revealing that, on average, the stars near the centre are older than the ones in the spiral arms, full of young stars produced by the still active processes of star formation. It is here, in the spiral arms, where one should expect a higher frequency of some specific types of supernovae, specifically those that mark the catastrophic end for massive, quick-living stars (such stars time ago disappeared in the aged centre of spiral galaxies). Indeed two such supernovae have been found in the spiral arms of this galaxy, in 2002 and 2003, respectively (supernova 2002ap was a peculiar Ib/c explosion, while supernova 2003gd was a type II event). Their light was useful to better calibrate the supernova-based measurement of distances, by comparing their implications with the results yielded by other methods based on classical variable stars.
Documentary Photo Gallery of Descubre Foundation (Descubre/DSA/OAUV), obtained at Calar Alto Observatory. Vicent Peris (OAUV), José Luis Lamadrid (CEFCA), Jack Harvey (SSRO), Steve Mazlin (SSRO), Ivette Rodríguez (PTeam), Oriol Lehmkuhl (PTeam), Juan Conejero (PixInsight). Image scale: 0.5” per pixel. The image comprises 15 arcminutes on the sky (half the apparent width of the full Moon). North up, East left. Entirely processed with PixInsight 1.6.
Color balancing of the image has been done in the same way as in the NGC 7331 image. By taking as white reference the whole light coming from the main galaxy, we can maximize the representation of color hues in the scene. Such color representation is not of universal validity, but relative to the specific chromatic content of this scene. This approach lets us to distinguish the different stellar populations inside the galaxy, from the younger and hot bluish stars in the outer regions, to the older and colder reddish ones at the central areas. The image accumulates a total exposure time of 19 hours through Johnson B, V and R filters, as well as in H-α emission light.
Photographing this galaxy in H-α light reveals a rich and complex spiral structure traced by clouds composed by ionised hydrogen, denoting the presence of intense stellar formation activity inside these areas. At the same time, the long integration time, linked to good seeing conditions, reveal aspects seldom displayed in such small portions of the sky. Not only the frame is overflowed by the spiral arms, but we can see in the background the redshifted light of the very distant —in time and space— galaxies that populated the universe several billion years ago. | 0.852667 | 3.9742 |
Not only do apples fall close to the tree, but the tree’s history can strongly influence the taste of the apple.
Something similar can be said for planets. If you want to get to know a faraway planet better, say a small, rocky world tens or hundreds of light-years away, you’d best start by getting to know its star.
In reality, we can’t even find most planets outside our solar system — exoplanets — without help from their stars. Every planet detection method known requires a detailed dossier on the star, with very few exceptions: finding “rogue planets” that mysteriously wander the galaxy without stellar companions, and planets that are directly imaged – capturing pixels of light from the planets themselves. These directly imaged planets represent only a tiny fraction of the thousands of exoplanets discovered in our galaxy so far — and even they require, first, the detection of the star itself.
“We’re now entering this era of really trying to understand the structure and composition of the planets, trying to understand what kinds of systems planets can exist in,” said astronomer David Ciardi of NASA’s Exoplanet Science Institute (NExScI) at Caltech. “The star is the most dominant part of a solar system; it has the most mass, the most energy influence. We’re studying these systems holistically — not just an individual rock.”
If you put the question to Karl Stapelfeldt, chief scientist for NASA’s Exoplanet Exploration Program, he’ll simply run down the list of exoplanet detection methods that require intimate knowledge of the host star:
- Radial velocity — measuring the wobbles in the movement of a star caused by gravitational tugs from an orbiting planet — can reveal the mass, or heft, of the target exoplanet. But that only works if you know, to high accuracy, the mass of the star.
- The transit method — looking for a tiny dip in starlight as a planet crosses the face of its star — can tell you the length of the planet’s year, or once around the star, by watching how often the dip repeats. But knowing the size of that orbit, or the planet’s distance from the star, requires measurement of a star’s mass. The star’s diameter is needed as well; then the size of the dip in starlight will reveal the size of the planet.
- It’s the same story for other detection methods, including gravitational microlensing — using magnification of light from a background star to reveal a star and its exoplanet in the foreground — and astrometry, another way of finding exoplanets by tracking stellar motions.
Seeing by starlight
Such star measurements are indispensable for NASA’s newest space-based planet hunter, TESS (the Transiting Exoplanet Survey Satellite). They can reveal even more about planets when combined with asteroseismology, or the measurement of “star quakes.”
“The [starlight measurements] we get from TESS can help provide precise stellar radii for the brightest stars via asteroseismology,” said Knicole Colón, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and a member of the TESS team. “Knowing the sizes of stars lets us measure sizes of planets precisely. TESS data can also help us measure ages of stars, in turn providing an estimate of the ages of planets.”
Want to know an exoplanet’s temperature? Unless it is so hot that it’s emitting its own light, you’ll need to know its orbital distance from the star (see the transit method) and the star’s luminosity, or how much sheer power the star radiates (think light-bulb wattage).
Learning how big around the planet is, what it’s made of, even the composition of its atmosphere — you guessed it. Knowledge of the star is critical. Planets generally form from the same cloud of gas and dust as their host star. So elements found in a star’s atmosphere have direct bearing on its planets.
“It’s interesting to have stellar elemental abundances to go along with those of the planet, as the combination informs theories of planet formation and evolution,” Stapelfeldt said. “In both cases, the abundances are derived from taking a spectrum” — that is, analyzing the spectrum of light from stars and planets to reveal elements in their atmospheres.
Or we can view the other side of the question: Without needed measurements, can the star fool us into thinking it has a planet that isn’t really there?
Many stars move in orbital duets with companion stars, which can look a lot like planets. Others play host to giant objects called brown dwarfs, a kind of “failed star” that is considered neither a star nor a planet.
And failure to properly account for a star’s pulses, jitters and other variations can lead to a vexing problem: phantom planets.
“The star itself is often also exhibiting variability that can masquerade as a planet signal,” said Jennifer Burt, a postdoctoral exoplanet researcher at NASA’s Jet Propulsion Laboratory in Pasadena, California.
Among these variations: star spots (our Sun’s version are called sunspots). “The star’s rotation period dictates how star spots rotate on and off the side of the star we can see from Earth,” Burt said.
Especially in the early days of exoplanet discovery, insufficient understanding of stellar rotation led to “false positives” – signals that at first appeared to be planets, but actually came from other sources upon closer inspection. Those exoplanet announcements were then withdrawn.
It’s a major problem for one of the most intriguing classes of exoplanets: rocky, Earth-sized worlds that orbit within the “habitable zone” of red-dwarf stars, also called M-dwarfs. If such planets possess atmospheres, some could be at just the right temperature for liquid water to pool on the surface. The seven planets of TRAPPIST-1 form a system with multiple Earth-size worlds in this special zone.
However, the rotation period of the star can be similar to the orbital period of planets in the habitable zones, according to Eric Mamajek, deputy program scientist for NASA’s Exoplanet Exploration Program.
A year on such planets — once around the star — might take 10 days, and "10 days is not unusual for the rotation period of an M-dwarf," he said.
If a star's rotation takes about the same time as a planet's orbit, it's difficult to tell the two apart. It's still possible to confirm the planet is there; it just takes a lot more work.
Bottom line: The star is in charge. It's why even careful study of our own sttar, the Sun, can help us better understand exoplanets.
"Everything we derive with regard to the characteristics of the planet — the size of the planet, the mass, the atmosphere — is all done relative to the star," Ciardi says. "You need to know the star in order to know the planet." | 0.855275 | 3.980229 |
Depiction of Mariner 2 in space
|Mission type||Planetary flyby|
|Operator||NASA / JPL|
|Harvard designation||1962 Alpha Rho 1|
|Mission duration||4 months, 7 days|
based on Ranger Block I
|Manufacturer||Jet Propulsion Laboratory|
|Launch mass||202.8 kilograms (447 lb)|
|Power||220 watts (at Venus encounter)|
|Start of mission|
|Launch date||August 27, 1962, 06:53:14UTC|
|Rocket||Atlas LV-3 Agena-B|
|Launch site||Cape Canaveral LC-12|
|End of mission|
|Last contact||January 3, 19637:00 UT|
|Perihelion||105,464,560 kilometers (56,946,310 nautical miles)|
|Epoch||December 27, 1962|
|Flyby of Venus|
|Closest approach||December 14, 1962|
|Distance||34,773 kilometers (18,776 nautical miles)|
Mariner 2 was launched on August 27, 1962 aboard an Atlas-Agena B rocket at Cape Canaveral Air Force Station. The aim of the Mariner 2 mission was to fly-by the planet Venus and return information on the planet's atmosphere, magnetic field, charged particle environment, and mass. Mariner 2 was at its closest to Venus, at a distance of 34,773 km, on December 14, 1962. Orbital perihelion was on December 27, 105,464,560 km away. The last radio signal from Mariner 2 was received on January 3, 1963. Mariner 2 is still orbiting around the Sun today.
The spacecraft's design was exactly the same as that of Mariner 1. Mariner 1 was the first spacecraft in the Mariner program, but it had to be destroyed shortly after launch because its trajectory was wrong.
The spacecraft found out that the surface temperature on Venus was at least 425 °C (797 °F), on both the day and night sides. It discovered that Venus rotates in the opposite direction from most planets in the Solar System. The spacecraft also found that the atmosphere of Venus is mostly of carbon dioxide and that there is a very high pressure at the planet's surface. Continuous cloud cover was detected but no magnetic field was, however. It also found that solar wind is continuous and that the density of cosmic dust between planets is much lower than it is near Earth.
- McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 12 September 2013. | 0.871665 | 3.51723 |
Planetary ping-pong might have built the strange worlds known as hot Jupiters. Fresh research suggests that collisions between young planets could have formed the cores of these massive gas giants, challenging the long-held idea that they migrated in from the outer edges of their systems.
Most of the first exoplanets identified were hot Jupiters, gas giants that orbit their stars in days or even hours.
“The presence of hot Jupiters has been a major surprise with planet-hunting, and their existence has immediately challenged planet-formation theory,” says Aaron Boley of the University of British Columbia in Vancouver, Canada.
Early theories suggested that these worlds must have formed at least as far from their stars as Earth is from our sun, before moving inward.
But the influx of planets discovered with NASA’s Kepler telescope challenged that idea. Kepler has spotted large, rocky planets called super-Earths and mini-Neptunes orbiting near their stars. Such planets should have gathered gas and dust as they travelled inward, ultimately becoming gas giants. The fact that they remained rocky suggested they could have formed closer to their stars.
In addition, the telescope has turned up systems where several rocky planets are packed closely with their star, which researchers call systems of tightly packed inner planets (STIPs). Most of these systems will eventually become unstable and send their planets crashing into one another.
If those collisions happened slowly enough, the planets could stick together and form the core of a new planet. And if they happened before the material around the star dissipated, which takes about 10 million years, that core could grab on to enough gas and dust to become a hot Jupiter.
To test this idea, Boley and his colleagues added instabilities to a computer model of Kepler-11, a system that contains six rocky planets orbiting closer to their star than Mercury does to the sun. Their simulations produced several warm Jupiters – gas giants just a bit further from their stars than hot Jupiters. The team attributed this difference to the particular arrangement of Kepler-11’s planets, and say different configurations should result in the overheated gas giants.
This doesn’t mean that planets never migrate in towards their stars, Boley adds – but it might not be the dominant method of building warm and hot Jupiters.
“It fits in really nicely with the idea of STIPs becoming unstable,” says Kathryn Volk of the University of Arizona in Tucson. “This is a totally different way of thinking about [hot Jupiter] formation.”
(Image credit: NASA, ESA & G. Bacon)
More on these topics: | 0.826745 | 4.011175 |
I haven’t done a proper science post for a while and I’m sorry for that. I saw a news story pop up on Twitter from the ESA Science Team (@esascience) about the origin of Earth’s water. Just where did it come from?
This is an area that really interests me, in fact I get rather too excited about it. We had a long and detailed question on it pop up in S283 (an OU planetary science course) and I thoroughly enjoyed researching and developing my answer. I leapt at this chance to discuss it further.
It’s pretty obvious surely? Comets right? They’re mainly composed of water ice, we know the planets were pummeled by them in the late heavy bombardment about 4 billion years ago, its got to be them hasn’t it?
There has been no way to test this hypothesis until very recently. You need to send a spacecraft to a comet to test it – a very expensive but totally worthwhile test.
Now we’ve finally managed to study 4 comets in detail and the results are interesting. What we need to study is what’s called the deuterium/hydrogen isotope ratio. Deuterium is just basically a slightly heavier version of hydrogen, it has an extra neutron (technically not an extra one because hydrogen doesn’t have any neutrons).
If comets are the origin of the Earth’s water we’d expect there to be a very similar ratio of hydrogen and deuterium to the ratio of these isotopes in ocean water. From the comets that have been studied it turns out that this probably isn’t the case. Comets appear to have twice as much deuterium than ocean water, meaning that comets are an unlikely cause for our waters origins. As we’ve said already though, only a few comets have been analysed in detail. They might not be representative of all comets.
Another theory states that water-bearing grains are responsible. The distance from the Sun at which the Earth formed though casts doubt on this. It would have been so warm that water couldn’t have existed here. Not if they were incorporated within hydrated minerals though. As the planet formed (and after) these hydrated minerals would, over time, degas out into the atmosphere via volcanic eruptions. Eventually, enough was degassed to form today’s oceans. This has been held as the most plausible explanation.
A spanner seems to have been thrown in the works though, the debate has been reignited. The Herschel infrared space observatory has been looking at comet Hartley 2 and has found that its deuterium/hydrogen ratio is pretty much exactly the same as Earth’s oceans. This comet is suspected to originally have been a trans-Neptunian object flung into the inner solar system have a gravitational tug of war. These comets, forming under different conditions to those that formed between Jupiter and Saturn, probably have slightly different compositions, specifically the deuterium/hydrogen ratio.
A recent study shows that there was likely a 5th giant planet in the solar system, but after gravitational encounters with other planets was flung out of the solar system, stirring up all the trans-Neptunian comets on its way. Is this the reason for the late heavy bombardment? It lends weight to comets being the origin of Earth’s water.
I’m still sceptical though. This is only one comet. We’re going to need to study many, many more before we reach a definitive conclusion. From what I’ve studied, hydrated minerals seem to fit best with the available evidence, but as more comes in I’m willing to change my mind.
- Definition of a Planet in the Solar System (articles4friends.com)
- Comets may have helped seeds of life to germinate (yorkshirepost.co.uk)
- New evidence that comets deposited building blocks of life on primordial Earth (naturenplanet.com)
- NASA Juno MIssion Will Prove Earth Origin (acksblog.firmament-chaos.com)
- Kuiper Belt (articles4friends.com) | 0.910547 | 3.36851 |
Mercury and Saturn will share the same right ascension, with Mercury passing 3°03' to the south of Saturn.
Mercury will be at mag -0.3, and Saturn at mag 0.4, both in the constellation Sagittarius.
The pair will be too widely separated to fit within the field of view of a telescope, but will be visible to the naked eye or through a pair of binoculars.
A graph of the angular separation between Mercury and Saturn around the time of closest approach is available here.
The positions of the two objects at the moment of conjunction will be as follows:
|Object||Right Ascension||Declination||Constellation||Magnitude||Angular Size|
The coordinates above are given in J2000.0. The pair will be at an angular separation of 21° from the Sun, which is in Scorpius at this time of year.
|The sky on 28 November 2017|
10 days old
All times shown in EST.
The circumstances of this event were computed using the DE405 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).
This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.
|15 Jun 2017||– Saturn at opposition|
|21 Dec 2017||– Saturn at solar conjunction|
|17 Apr 2018||– Saturn at aphelion|
|27 Jun 2018||– Saturn at opposition| | 0.898291 | 3.172224 |
Mysterious red spots on Mercury get names – but what are they?
Mercury is the closest planet to the sun, but far from being a dull cinder of a world, it has instead turned out to be a real eye opener for geologists. Among the revelations by NASA's MESSENGER probe, which first flew past Mercury in 2008 and orbited it between 2011 and 2015, is the discovery of a hundred or so bright red spots scattered across the globe. Now they are at last being named.
Although they appear more yellow-orange than red on the accompanying colour-enhanced images, they are the reddest features on Mercury, a planet that looks dull and grey on unenhanced images. Most have 10-50km wide irregularly-shaped holes at their centres. Scientists soon interpreted the holes as volcanic vents and the spots as material thrown out by volcanic explosions. Explosive volcanism was not expected at Mercury, because formation of a planet close to the heat of the sun should have deprived it of the gaseous content necessary to power explosions.
But MESSENGER revealed multiple lines of evidence showing that Mercury is actually quite rich in so-called "volatile components". These include direct measurements of abundant sulphur, carbon, potassium and chlorine, and the discovery of patches of shallow hollows where it looks as if some unknown volatile material near the ground surface has been somehow dissipated into space.
Maybe this means that Mercury is actually the remains of an interloper from somewhere beyond the Earth's orbit, where volatile material was available in greater amounts during planet formation. A "hit and run" impact with the Earth or Venus in the early stages of their formation while Mercury was migrating inwards towards its present orbit close to the sun could have stripped it of much of its original rock, leaving the dense but volatile-rich body we see today.
Whatever Mercury's origin, the red spots and their source vents demonstrate explosive volcanic activity that in some cases likely continued into the most recent billion years of Mercury's 4.5 billion year history. Scientists deduce this because some of the vents puncture young lava flows or the floors of young impact craters.
Overlapping structures within some vents show that they result from a succession of explosions at sites several kilometres apart. From this it can be inferred that each red spot is the accumulated product of several eruptions from its vent.
Deciphering the relationships between explosive eruptions, lava flows, the growth of hollows and fault movements is among the major tasks for the forthcoming European-Japanese mission to Mercury, BepiColombo, and is the kind of problem that excites planetary geologists.
Snakes on a planet
So why do the red spots need names, and how were the names decided? Names are needed for features on planets because it is cumbersome and unmemorable to refer to them merely by geographic coordinates. Names are allocated by nomenclature working groups of the International Astronomical Union, whose job is to achieve clarity and consistency, while also seeking fair representation of Earth's many cultures.
Craters are given single word names, but names of most other features are in two parts: a specific name plus a descriptor term. The descriptor term is a word (usually of Latin origin) specifying what each type of feature looks like, but without implying that we know for certain how it formed. For example, we have "vallis" for valley, "planitia" for low plain, "planum" for high plain, and so on. The specific names used for each type of feature follow a convention adopted for each planet.
In the case of Mercury's red spots, it is the spots themselves rather than the presumed volcanic vents at their centres that have been named. The chosen descriptor term is "facula", which is already used for "bright spot" on various other planetary bodies. The theme chosen for the specific names of faculae on Mercury is the word "snake" in various languages. For example, the three faculae near Rachmaninoff crater have been named Nathair Facula, Neidr Facula and Suge Facula, using "snake" in three minority European languages: Irish, Welsh and Basque.
Ten faculae in Mercury's Caloris basin have so far been named each in a different African language. This means that scientists can now refer consistently to Agwo Facula (using the Igbo, southeastern Nigeria, word for snake) rather than "the spot around that kidney-shaped vent in the southwest of the Caloris basin".
But why snake? Other than being a convenient way to draw names from all over the world, there does not have to be a reason for the choice of name. However, the Greek god Hermes and his Roman equivalent Mercury were traditionally portrayed bearing a staff entwined by two snakes, so using snakes as a theme is a nice, incidental, nod to classical mythology. | 0.853859 | 3.897434 |
With Mars methane mystery unsolved, Curiosity serves scientists a new one: Oxygen
For the first time in the history of space exploration, scientists have measured the seasonal changes in the gases that fill the air directly above the surface of Gale Crater on Mars. As a result, they noticed something baffling: oxygen, the gas many Earth creatures use to breathe, behaves in a way that so far scientists cannot explain through any known chemical processes.
Over the course of three Mars years (or nearly six Earth years) an instrument in the Sample Analysis at Mars (SAM) portable chemistry lab inside the belly of NASA's Curiosity rover inhaled the air of Gale Crater and analyzed its composition. The results SAM spit out confirmed the makeup of the Martian atmosphere at the surface: 95% by volume of carbon dioxide (CO2), 2.6% molecular nitrogen (N2), 1.9% argon (Ar), 0.16% molecular oxygen (O2), and 0.06% carbon monoxide (CO). They also revealed how the molecules in the Martian air mix and circulate with the changes in air pressure throughout the year. These changes are caused when CO2 gas freezes over the poles in the winter, thereby lowering the air pressure across the planet following redistribution of air to maintain pressure equilibrium. When CO2 evaporates in the spring and summer and mixes across Mars, it raises the air pressure.
Within this environment, scientists found that nitrogen and argon follow a predictable seasonal pattern, waxing and waning in concentration in Gale Crater throughout the year relative to how much CO2 is in the air. They expected oxygen to do the same. But it didn't. Instead, the amount of the gas in the air rose throughout spring and summer by as much as 30%, and then dropped back to levels predicted by known chemistry in fall. This pattern repeated each spring, though the amount of oxygen added to the atmosphere varied, implying that something was producing it and then taking it away.
"The first time we saw that, it was just mind boggling," said Sushil Atreya, professor of climate and space sciences at the University of Michigan in Ann Arbor. Atreya is a co-author of a paper on this topic published on November 12 in the Journal of Geophysical Research: Planets.
As soon as scientists discovered the oxygen enigma, Mars experts set to work trying to explain it. They first double- and triple-checked the accuracy of the SAM instrument they used to measure the gases: the Quadrupole Mass Spectrometer. The instrument was fine. They considered the possibility that CO2 or water (H2O) molecules could have released oxygen when they broke apart in the atmosphere, leading to the short-lived rise. But it would take five times more water above Mars to produce the extra oxygen, and CO2 breaks up too slowly to generate it over such a short time. What about the oxygen decrease? Could solar radiation have broken up oxygen molecules into two atoms that blew away into space? No, scientists concluded, since it would take at least 10 years for the oxygen to disappear through this process.
"We're struggling to explain this," said Melissa Trainer, a planetary scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland who led this research. "The fact that the oxygen behavior isn't perfectly repeatable every season makes us think that it's not an issue that has to do with atmospheric dynamics. It has to be some chemical source and sink that we can't yet account for."
To scientists who study Mars, the oxygen story is curiously similar to that of methane. Methane is constantly in the air inside Gale Crater in such small quantities (0.00000004% on average) that it's barely discernable even by the most sensitive instruments on Mars. Still, it's been measured by SAM's Tunable Laser Spectrometer. The instrument revealed that while methane rises and falls seasonally, it increases in abundance by about 60% in summer months for inexplicable reasons. (In fact, methane also spikes randomly and dramatically. Scientists are trying to figure out why.)
With the new oxygen findings in hand, Trainer's team is wondering if chemistry similar to what's driving methane's natural seasonal variations may also drive oxygen's. At least occasionally, the two gases appear to fluctuate in tandem.
"We're beginning to see this tantalizing correlation between methane and oxygen for a good part of the Mars year," Atreya said. "I think there's something to it. I just don't have the answers yet. Nobody does."
Oxygen and methane can be produced both biologically (from microbes, for instance) and abiotically (from chemistry related to water and rocks). Scientists are considering all options, although they don't have any convincing evidence of biological activity on Mars. Curiosity doesn't have instruments that can definitively say whether the source of the methane or oxygen on Mars is biological or geological. Scientists expect that non-biological explanations are more likely and are working diligently to fully understand them.
Trainer's team considered Martian soil as a source of the extra springtime oxygen. After all, it's known to be rich in the element, in the form of compounds such as hydrogen peroxide and perchlorates. One experiment on the Viking landers showed decades ago that heat and humidity could release oxygen from Martian soil. But that experiment took place in conditions quite different from the Martian spring environment, and it doesn't explain the oxygen drop, among other problems. Other possible explanations also don't quite add up for now. For example, high-energy radiation of the soil could produce extra O2 in the air, but it would take a million years to accumulate enough oxygen in the soil to account for the boost measured in only one spring, the researchers report in their paper.
"We have not been able to come up with one process yet that produces the amount of oxygen we need, but we think it has to be something in the surface soil that changes seasonally because there aren't enough available oxygen atoms in the atmosphere to create the behavior we see," said Timothy McConnochie, assistant research scientist at the University of Maryland in College Park and another co-author of the paper.
The only previous spacecraft with instruments capable of measuring the composition of the Martian air near the ground were NASA's twin Viking landers, which arrived on the planet in 1976. The Viking experiments covered only a few Martian days, though, so they couldn't reveal seasonal patterns of the different gases. The new SAM measurements are the first to do so. The SAM team will continue to measure atmospheric gases so scientists can gather more detailed data throughout each season. In the meantime, Trainer and her team hope that other Mars experts will work to solve the oxygen mystery.
"This is the first time where we're seeing this interesting behavior over multiple years. We don't totally understand it," Trainer said. "For me, this is an open call to all the smart people out there who are interested in this: See what you can come up with." | 0.83111 | 4.020962 |
New evidence shows that the key assumption made in the discovery of dark energy is in error
The most direct and strongest evidence for the accelerating universe with dark energy is provided by the distance measurements using type Ia supernovae (SN Ia) for the galaxies at high redshift. This result is based on the assumption that the corrected luminosity of SN Ia through the empirical standardization would not evolve with redshift.
New observations and analysis made by a team of astronomers at Yonsei University (Seoul, South Korea), together with their collaborators at Lyon University and KASI, show, however, that this key assumption is most likely in error. The team has performed very high-quality (signal-to-noise ratio ~175) spectroscopic observations to cover most of the reported nearby early-type host galaxies of SN Ia, from which they obtained the most direct and reliable measurements of population ages for these host galaxies. They find a significant correlation between SN luminosity and stellar population age at a 99.5 percent confidence level. As such, this is the most direct and stringent test ever made for the luminosity evolution of SN Ia. Since SN progenitors in host galaxies are getting younger with redshift (look-back time), this result inevitably indicates a serious systematic bias with redshift in SN cosmology. Taken at face values, the luminosity evolution of SN is significant enough to question the very existence of dark energy. When the luminosity evolution of SN is properly taken into account, the team found that the evidence for the existence of dark energy simply goes away (see Figure 1).
Commenting on the result, Prof. Young-Wook Lee (Yonsei Univ., Seoul), who led the project said, "Quoting Carl Sagan, extraordinary claims require extraordinary evidence, but I am not sure we have such extraordinary evidence for dark energy. Our result illustrates that dark energy from SN cosmology, which led to the 2011 Nobel Prize in Physics, might be an artifact of a fragile and false assumption."
Other cosmological probes, such as the cosmic microwave background (CMB) and baryonic acoustic oscillations (BAO), are also known to provide some indirect and "circumstantial" evidence for dark energy, but it was recently suggested that CMB from Planck mission no longer supports the concordance cosmological model which may require new physics (Di Valentino, Melchiorri, & Silk 2019). Some investigators have also shown that BAO and other low-redshift cosmological probes can be consistent with a non-accelerating universe without dark energy (see, for example, Tutusaus et al. 2017). In this respect, the present result showing the luminosity evolution mimicking dark energy in SN cosmology is crucial and very timely.
This result is reminiscent of the famous Tinsley-Sandage debate in the 1970s on luminosity evolution in observational cosmology, which led to the termination of the Sandage project originally designed to determine the fate of the universe.
This work based on the team's 9-year effort at Las Campanas Observatory 2.5-m telescope and at MMT 6.5-m telescope was presented at the 235th meeting of the American Astronomical Society held in Honolulu on January 5th (2:50 PM in cosmology session, presentation No. 153.05). Their paper is also accepted for publication in the Astrophysical Journal and will be published in January 2020 issue. | 0.842043 | 4.142338 |
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AST 109- Planetary Astronomy Exam #1
Ch. 1, 2. 3. 4. 5. 6.
Terms in this set (108)
Why would one of the letters RIVUXG be highlighted under a figure? What does this indicate?
The highlighted letter indicates that a filter was used for that image allowing only that portion of the electromagnetic spectrum to be recorded.
A scientific model is usually made up of what?
What is the difference between a theory and a law of physics?
A theory is a scientifically constructed description of how nature operates in a particular situation. Theories must be tested constantly and amended when necessary. After a theory has been tested many times over a long period of time without failure, it becomes known as a law of physics. It thus commands high (but not absolute) confidence in its predictive powers.
The solar system includes:
All objects that orbit the sun .
A key concept in the formation of solar systems is:
How many planets have we explored with the use of a robotic spacraft?
All eight planets from Mercury to Neptune
The age of our solar system is:
4.56 billion years, from the study of meteorites.
What is the process of stars?
Nebula, Star, Supernova
A supernova is a(n):
Explosion that rips a star apart, throwing debris into interstellar space.
In the Orion Nebula, the Nebulae are the:
Birthplace of stars
The 88 constellations in the sky are just:
Patterns of stars that only appear to be close to each other.
To a modern astronomer, the 88 constellations are just:
88 regions of the sky
(T/F) A sidreal day is longer than a solar day
(T/F) Stars set on the western horizon a little earlier everyday.
(T/F) Polaris is the brightest star in the sky.
The constellation of Andromeda is directly overhead California at midnight. Where would a person in Washington, D.C. look to view Andromeda at the same time (9 P.M. eastern time)?
To the west
A star is observed to be directly below Polaris at 6 P.M. Where do you expect to find the star later that night at 6 A.M. (twelve hours later)?
Directly above Polaris
(T/F) Seasons are caused by the fact that when one hemisphere is tilted towards the Sun, it is closer to the Sun, and therefore warmer.
(T/F) The Sun is directly overhead for people living on the equator exactly twice a year, on the equinoxes.
For people living in the continental United States, you would face______ to look directly at the Sun at noon on the summer solstice.
After a long night of partying, one of your friends yells "Road Trip!" You all hop in the car and keep driving. When you finally reach your destination it is noon and you see the Sun directly overhead. You look at the calendar and see that it is December 21st. At what latitude are you?
the Tropic of Capricorn (23.5° S)
Diurnal motion is the:
Apparent daily motion of the sky caused by the rotation of the Earth.
Suppose the star Sirius rises above the eastern horizon at 2:00 A.M. on a particular night. At what time will it rise four nights later?
Polaris, the North Star, is at the end of the handle of the Little Dipper. How do the stars of the Little Dipper move with respect to Polaris?
If the Sun's declination is 0° on March 21 of a particular year, how long will it be before it is at this declination again?
You are standing at the North Pole of the Earth at the time of the northern hemisphere summer solstice in June. What is the elevation of the Sun above the southern horizon?
In the northern hemisphere, houses are designed to have "southern exposure", that is, with the largest windows on the southern side of the house. But in the southern hemisphere, houses are designed to have "northern exposure." Why are houses designed this way, and why is there a difference between the hemispheres?
In the northern hemisphere the Sun appears toward the south, and in the southern hemisphere the Sun appears toward the north. The houses are designed this way to allow in as much sunlight as possible.
The path that the Sun takes as it moves through the heavens is called the
How many years does it take for the position of the north celestial pole to move one degree?
Ancient records show that 2000 years ago, the stars of the Southern Cross were visible in the southern sky from Greece. Today, however, these stars cannot be seen from Greece. What accounts for this change?
Precession has caused the celestial sphere to appear to move by several degrees, so that the stars of the Southern Cross no longer rise above the horizon as seen from Greece.
The meridian (or celestial meridian) is a line in the sky that always passes through the:
Observer's zenith and the north and south celestial poles.
What is the (fictitious) mean Sun?
The "mean Sun" is a point that moves along the celestial equator at a uniform rate.
What path does the mean sun follow on the celestial sphere?
The celestial equator.
Why is it convenient to divide the Earth into time zones?
It is convenient to divide the Earth into time zones so that noon according to the clock is close to the upper meridian crossing by the Sun.
In one solar day the Earth rotates through an angle of about 361°. A solar day is about 4 minutes longer than a sidereal day. How long is the sidereal day?
23 h 56 m
A tropical year is the:
The time between successive passages of the Sun through the vernal equinox as viewed from the Earth.
Pope Gregory XIII dropped 10 days from the calendar in 1582 because:
The assumption that a tropical year is 365 days is incorrect by over 11 minutes.
The name of one of the lunar phases in the Dakota language means "diminishing moon." To which phase would this term most likely apply?
The Moon is highest in the sky when it crosses the meridian, halfway between the time of moonrise and the time of moonset. What is the phase of the Moon if it is highest in the sky at midnight?
What is the phase of the Moon if it is highest in the sky at sunrise?
What is the phase of the Moon if it is highest in the sky at noon?
What is the phase of the Moon if it is highest in the sky at sunset?
The waxing gibbous Moon occurs during the seven days after:
the first quarter
Which way will the "horns," or sharp ends of the crescent, of the Moon point in the sky when the Moon is above the eastern horizon at sunrise at a phase 3 days before new moon?
Away from the sun, westward
At what phase in its monthly cycle will the Moon be seen high in the sky in the late afternoon from mid-latitudes?
A first-quarter Moon will cross the meridian at approximately
The plane of the Moon's orbit is inclined at a 5° angle from the ecliptic, and the ecliptic is inclined at a 23½° angle from the celestial equator. Could the Moon ever appear at your zenith if you lived at the equator?
The celestial equator is your zenith if you are at the equator. The Moon's orbit will be above the ecliptic at some times of the year and below at other times. Since the ecliptic can be above or below the zenith, the Moon will always have a declination (±28½°) that can place it at the zenith viewed from the equator.
Could the Moon ever appear at your zenith if you are at the south pole?
One definiton of a "blue moon" is the second full moon within the same calendar month. There is usually only one full moon within a calendar month, which is why the phrase "once in a blue moon" means "hardly ever." Why are blue moons so rare?
Full moons are separated by one synodic month, about 29 & 1/2 days. Since the longest months are 31 days long, a blue moon can occur only if the full moon happens to fall on the first day or early on the second day of the month, which does not happen very often. (For a 30-day month, the full moon would have to fall early on the first day.)
Are there any months of the year in which it would be impossible to have two full moons?
You are watching a lunar eclipse from some place on the Earth's night side. Will you see the Moon enter the Earth's shadow from the east or from the west?
The Moon moves eastward, so it enters the Earth's shadow from the west.
A lunar eclipse occurs when the:
Earth is exactly between the Moon and the Sun.
he reason eclipses do not occur at every new Moon and every full Moon is that the:
Moon's orbit is inclined at an angle to the Earth's orbit.
The nodes of the Moon's orbit are the points where the Moon:
Crosses the ecliptic
The Sun is at a node of the Moon's orbit, as seen from the Earth, and you are looking at a total lunar eclipse. What do you know about the location of the Moon in the sky?
It is at the opposite node from the Sun.
A solar eclipse can occur only when the Moon is:
If the plane of the Moon's orbit were the same as the ecliptic (the plane of the Earth's orbit), we would have
one solar eclipse and one lunar eclipse each month.
(T/F) A partial eclipse can be seen by fewer people at one time than a full eclipse can.
During an eclipse, the shadow of the Earth appears curved as it moves across the Moon because of the following:
The earth is round
On average, lunar eclipses occur about how often?
2 times a year
A total lunar eclipse is visible in principle (assuming clear skies everywhere):
To everyone in one hemisphere
Earth's shadow at the distance of the Moon's orbit from Earth is:
WIder than the moon
(T/F) Most people who observe a solar eclipse tend to observe a total solar eclipse.
(T/F) During a total solar eclipse, the Moon completely blocks our view of any part of the Sun.
How long do solar eclipses last, for an observer at a given location?
What if the Moon's orbit were larger than it currently is? Which type(s) of solar eclipse(s) would still occur?
Both partial and annual
Why do Eclipse paths move eastward across the Earth?
The Moons orbit around the earth
In what direction does a planet move relative to the stars when it is in direct motion?
In what direction does a planet move relative to the stars when it is in retrograde motion?
In what direction does the Sun move relative to the stars?
In what direction does a planet move relative to the horizon over the course of one night?
Retrograde motion of superior planets is explained in the Copernican model of the solar system as a(n):
illusion that happens when the Earth overtakes a superior planet in its orbit.
When a planet is at superior conjunction, the:
Sun is between the earth and the planet.
At which position is Jupiter seen at its highest in our sky at midnight?
Tycho Brahe was convinced that comets and stars were at great distances because they:
Exhibited no parallax
How did Tycho Brahe prove that the heavens are not permanent and unalterable?
A "new star" appeared in the sky, and he showed that the star exhibited no measurable parallax as the Earth rotated around its axis.
Tycho Brahe's most important contribution to the development of modern astronomy was the:
accurate measurement of planetary positions.
Kepler described how a planet's motion speeds up as it nears the Sun by his concept of:
"equal areas in equal times."
Why is the image formed by a simple refracting telescope upside down?
The rays of light entering the objective lens near the top emerge from the eyepiece near the bottom and vice versa.
An astronomical telescope has an objective lens with a focal length of 160 cm and an eyepiece lens with a focal length of 5 cm. What magnification does this telescope provide?
What is diffraction of light?
Spreading out of light waves after they pass through an opening such as the outer diameter of a lens or mirror.
A factor that has become much worse for many observatories and now severely limits the number of useful sites for astronomy in the world is:
Light pollution due to the increasing size of nearby cities.
What is active optics? Why is it useful?
Active optics is a continuous refocusing and aiming of the telescope. It helps to compensate for changing conditions in the atmosphere to produce a better image.
What is adaptive optics? Why is it useful?
Adaptive optics is a continuous changing of the shape of the telescope mirror. It helps to compensate for changing conditions in the atmosphere to produce a better image.
Would either active or adaptive optics be a good feature to include on a telescope to be placed in orbit?
No. Because both are designed to compensate for conditions in the atmosphere, these features would be wasted in orbit.
What is a charge-coupled device (CCD), now routinely used by astronomers instead of photographic film?
Rectangular array of tiny, photosensitive, semiconducting wafers
Astronomers use a spectrograph to:
Measure the distribution of intensity of light over a continuous range of wavelengths, or colors.
The first nonvisible radiation from outer space to be used to explore astronomical objects was:
Radio wavelengths are about a million times longer than visible wavelengths. One consequence is that:
Radio astronomy can "see" farther through the dust clouds in the plane of our galaxy than can visible light astronomy.
To which of the following types of radiation is the Earth's atmosphere transparent?
Radio and visible light
What was the very first observation that showed conclusively that light travels at a finite speed (not infinitely fast)?
Eclipses of Jupiter's moons, when they moved into or out of Jupiter's shadow, appeared to occur later than they should when Jupiter was farther away from Earth.
Approximately how many times around Earth (at the equator) could a beam of light travel in one second?
Historically, the wave nature of light was first demonstrated by:
The interference produced when light passes through a double slit.
Using Wien's law and the Stefan-Boltzmann law, explain the color and intensity changes that are observed as the temperature of a hot, glowing object increases
As the temperature of a hot, glowing object increases it will be seen to glow more brightly. This is described by the Stephan-Boltzmann law, which shows the emitted flux of radiation increasing with the fourth power of the temperature. The color of the glowing object will be seen to shift toward the short-wavelength end of the spectrum in accord with Wien's law, which shows the peak wavelength in the spectrum decreasing as the temperature increases.
There are no green stars because
As a star increases in temperature, the visible spectrum it produces changes from red to red plus green to red plus green plus blue, and none of these combinations looks green.
The important breakthrough in theoretical physics that was first suggested by Planck to explain the shape of the spectrum of a hot body was the:
concept that electromagnetic energy was emitted in small packets or quanta.
The first person to show that light traveled in wave packets, or photons, in which the energy of a photon depends on its wavelength, was
The physical structure of an atom is
negatively charged electrons moving around a very small but massive, positively charged core.
The overall diameter of a typical atom is about
10-10 m, or 0.1 nm.
According to the Bohr theory, light emitted by atoms originates from:
transitions of electrons between different energy levels in the atom.
When an electron in an atom makes a transition from a higher to a lower orbit, light is
emitted in an emission line
The specific colors of light emitted by an atom in a hot, thin gas (e.g., in a tube in a laboratory or a gas cloud in space) are caused by
electrons losing energy as they jump to lower levels
A hydrogen atom in a low-density, hot gas gives off what type of spectrum?
a series of emission lines spaced in a mathematical sequence
What is the Doppler effect?
The Doppler effect is a shift in the observed wavelength due to relative radial motion between the source of the waves and the observer.
Why is the Doppler effect important to astronomers?
The Doppler effect allows a determination of the relative radial velocity of a source of radiation from an examination of its spectrum.
What did Galileo see when he observed Jupiter through his telescope?
four satellites (moons) orbiting Jupiter
One proof of Galileo that the Copernican model of the solar system is correct was that
Venus goes through phases like the moon does
Kepler's laws apply:
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Growing Pains: The Formation Times and Building Blocks of Milky Way-mass Galaxies in the FIRE Simulations
Surveys of the Milky Way (MW) and M31 enable detailed studies of stellar populations across ages and metallicities, with the goal of reconstructing formation histories across cosmic time. These surveys motivate key questions for galactic archaeology in a cosmological context: when did the main progenitor of a MW/M31-mass galaxy form, and what were the galactic building blocks that formed it? We investigate the formation times and progenitor galaxies of MW/M31-mass galaxies using the FIRE-2 cosmological simulations, including 6 isolated MW/M31-mass galaxies and 6 galaxies in Local Group (LG)-like pairs at z = 0. We examine main progenitor "formation" based on two metrics: (1) transition from primarily ex-situ to in-situ stellar mass growth and (2) mass dominance compared to other progenitors. We find that the main progenitor of a MW/M31-mass galaxy emerged typically at z ~ 3-4 (11.6-12.2 Gyr ago), while stars in the bulge region (inner 2 kpc) at z = 0 formed primarily in a single main progenitor at z < 5 (< 12.6 Gyr ago). Compared with isolated hosts, the main progenitors of LG-like paired hosts emerged significantly earlier (\Delta z ~ 2, \Delta t ~ 1.6 Gyr), with ~ 4x higher stellar mass at all z > 4 (> 12.2 Gyr ago). This highlights the importance of environment in MW/M31-mass galaxy formation, especially at early times. Overall, about 100 galaxies with M_star > 10^5 M_sun formed a typical MW/M31-mass system. Thus, surviving satellites represent a highly incomplete census (by ~ 5x) of the progenitor population. | 0.845549 | 3.718255 |
Most of the normal matter in the universe (the kind of stuff that makes up our bodies, and our food, clothing and everything else) is strung out through space in a giant cosmic web. This web is marked not by stars or galaxies but by clusters of galaxies, enormous, gravitationally bound groups of dozens or hundreds of individual member galaxies. Most of the normal matter in these clusters of galaxies is contained not in the member galaxies themselves, but in the intra-cluster medium, an enormous amount of gas which lies between the member galaxies. This gas is actually invisible, but because it's heated by motions of the galaxies as they pass through it, and by supernovae and black hole outbursts, it becomes so hot that it emits X-rays. X-ray images of galaxy clusters are therefore an important way in which astronomers determine how much normal matter the clusters contain. The image above is a rogue's gallery of the X-ray images of 365 clusters of galaxies taken by the XMM-Newton X-ray space observatory as part of the XXL Survey, on of the largest surveys of galaxy clusters in the X-ray band. Because of the extraordinary sensitivity of XMM-Newton, many of the clusters are so far away that the X-rays seen by XMM-Newton left the clusters when the Universe was less than half its present age. The results of the XXL Survey are being used by scientists to test models of cosmology, predictions of the distribution of normal matter in the Universe, and to place stricter constraints on the nature of the mysterious Dark Energy which drives the Universe apart, and to understand its relation to Einstein's biggest blunder.
ESA: Tracing the Universe: X-ray survey supports standard cosmological model
The XXL Survey: Second Series ~ XXL Consortium
- Astronomy & Astrophysics: Special Issue 620 (Dec 2018)
|<< Previous HEAPOW||High Energy Astrophysics Picture of the Week||Next HEAPOW >>| | 0.819102 | 3.946446 |
On 4 July 2016 the NASA spacecraft Juno will arrive at Jupiter after a 5 year journey. It will be the ninth space probe to visit the planet. The first was Pioneer 10, which flew past in December 1973, (see notes). Juno will go into an orbit around the planet which will take it close to its poles. It will remain in that orbit until the end of the mission when it will be deliberately steered into Jupiter so that it can take measurements as it descends through the atmosphere. It will be destroyed by the intense temperatures and pressures, but the alternative would just be to leave it in orbit forever as a dead spacecraft, missing the chance for it to find new scientific information as it makes its final descent.
Image from NASA
As nearly all my readers will know, Jupiter is the largest planet in the Solar System. Its diameter is on average 140,000 km which is roughly 11 times that of the Earth, making its volume 1320 times larger (Williams 2016). Unlike the inner planets (Mercury, Venus, Earth and Mars) which have large iron cores surrounded by rocky materials, Jupiter is mainly composed of gas. It is not known if it has a solid core, but if one exists it will only make up a small proportion of the planet. Being made up of largely of gas means that its density is only 25% that of the Earth. Even so, its mass is still 320 times greater, making it more massive than all the other planets, moons, asteroids and comets in the Solar System put together.
Image from NASA
It has a magnetic field which is 15 times stronger than the Earth’s and extends millions of kilometres into space. The magnetic field traps electrically charged particles so that they are confined into a ring-shaped structured around the planet. These trapped particles emit electromagnetic radiation. This causes Jupiter to be surrounded by deadly radiation belts, which would be lethal to any space travellers who ventured too close to the planet.
It has its own mini “solar system” of over 60 moons in orbit around it. The four largest moons were discovered by Galileo in 1610 and one of them, Ganymede, the largest moon in the solar system, is bigger than the planet Mercury. The innermost moon Io is the most volcanically active object known to exist anywhere. Europa, the second innermost, is of particular interest because its surface is composed of ice underneath which are thought to lie oceans of liquid water, warmed by a process called tidal friction. Many scientists think that Europa is one of the most promising places in the Solar System to find extraterrestrial life. Unfortunately Juno will not be studying Jupiter’s moons. However the European Space Agency (ESA) is planning a mission called JUpiter ICy moon Explorer (JUICE) to study Europa, Ganymede and Callisto.
The four large moons of Jupiter: Io, Europa, Ganymede and Callisto. Image from NASA
Unlocking Jupiter’s secrets
Despite being visited eight times by previous spacecraft, there is much that is unknown about Jupiter. The Juno website (NASA 2016) states that the mission will achieve the following:
- ‘Determine how much water is in Jupiter’s atmosphere, which helps determine which planet formation theory is correct (or if new theories are needed)
- Look deep into Jupiter’s atmosphere to measure composition, temperature, cloud motions and other properties
- Map Jupiter’s magnetic and gravity fields, revealing the planet’s deep structure
- Explore and study Jupiter’s magnetosphere near the planet’s poles, especially the auroras – Jupiter’s northern and southern lights – providing new insights about how the planet’s enormous magnetic force field affects its atmosphere.’
The key instruments on the probe are:
- A microwave receiver which measures radio-waves with very short wavelengths knows as microwaves. These are the only waves able to travel through the thick atmosphere on Jupiter. This instrument will measure the abundance of water and ammonia and the temperature profile in the deeper layers of the atmosphere, up to 600 km below the top.
- An instrument which can take pictures in infrared which will be used to map regions of high temperature known as hot spots in the top of the atmosphere.
A picture of a hot spot taken in infrared light – Image from NASA
- A magnetometer to accurately map Jupiter’s magnetic field.
- An instrument to measure small fluctuations in the probe’s speed and direction of travel as it orbits. The small fluctuations are caused by unevenness in Jupiter’s gravitational field due to the way that mass is distributed inside the planet.
- A visible light camera/telescope called Junocam. This is only expected to survive seven orbits around Jupiter because of the planet’s damaging radiation and magnetic field.
- Instruments to measured charged particles near the poles of Jupiter.
Why the name Juno?
Juno stands for JUpiter Near-polar Orbiter,
The planet Jupiter is named after the Roman king of the gods. In Roman mythology, Jupiter drew a veil of clouds around himself to hide his mischief. Jupiter had a wife, the goddess Juno, the warlike queen of the gods. According to legends Juno was able to look through Jupiter’s clouds and see his true nature.
“The Juno spacecraft will also look beneath the clouds to see what the planet is up to, not seeking signs of misbehavior, but helping us to understand the planet’s structure and history.” (NASA 2016)
Jupiter and Juno Image from Wikimedia commons
How much has Juno cost?
Missions to other planets are expensive and this is no exception – so far the spacecraft has cost $1.1 billion (Lufkin 2016). Most of this was spent before its launch in 2011. The total cost in 2016 dollars will be around $1.3 billion. Although this is a large amount of money, it only works out at about $4 for each person in the US and is less than 1% of the cost (in 2016 dollars) of the Apollo programme to put a man on the Moon.
I hope you’ve enjoyed this post. I hope that over the next couple of years Juno will make lots of exciting discoveries, which will enable us to find out more about the giant planet. If you want to find out more about the Juno mission visit the Juno website:
1 The following spacecraft have visited Jupiter: Pioneer 10 (1973) shown below, Pioneer 11 (1974), Voyager 1 and Voyager 2 (both 1979), Ulysses (1992), Galileo (1995-2003) Cassini (2000), New Horizons (2007). Galileo spent 8 years orbiting the planet; the other spacecraft flew past the planet on the way to view other targets.
Image from NASA
Lufkin, B. (2016) NASA’s Juno Spacecraft Is Scheduled to Arrive at Jupiter on July 4, Available at:http://www.scientificamerican.com/article/nasa-s-juno-spacecraft-is-scheduled-to-arrive-at-jupiter-on-july-4/ (Accessed: 25 June 2016).
NASA (2016) Juno Overview, Available at:http://www.nasa.gov/mission_pages/juno/overview/index.html (Accessed: 16 June 2016).
Williams, D. R. (2016) Jupiter Fact Sheet, Available at:http://nssdc.gsfc.nasa.gov/planetary/factsheet/jupiterfact.html (Accessed: 14 June 2016). | 0.880181 | 3.736814 |
Crescent ♒ Aquarius
Moon phase on 14 December 2015 Monday is Waxing Crescent, 3 days young Moon is in Capricorn.Share this page: twitter facebook linkedin
Previous main lunar phase is the New Moon before 3 days on 11 December 2015 at 10:29.
Moon rises in the morning and sets in the evening. It is visible toward the southwest in early evening.
Lunar disc appears visually 2.6% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1900" and ∠1949".
Next Full Moon is the Cold Moon of December 2015 after 10 days on 25 December 2015 at 11:11.
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 3 days young. Earth's natural satellite is moving from the beginning to the first part of current synodic month. This is lunation 197 of Meeus index or 1150 from Brown series.
Length of current 197 lunation is 29 days, 15 hours and 1 minute. It is 1 hour and 53 minutes longer than next lunation 198 length.
Length of current synodic month is 2 hours and 17 minutes longer than the mean length of synodic month, but it is still 4 hours and 46 minutes shorter, compared to 21st century longest.
This lunation true anomaly is ∠255.6°. At the beginning of next synodic month true anomaly will be ∠292.2°. 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°).
8 days after point of apogee on 5 December 2015 at 14:56 in ♎ Libra. The lunar orbit is getting closer, while the Moon is moving inward the Earth. It will keep this direction for the next 6 days, until it get to the point of next perigee on 21 December 2015 at 08:53 in ♉ Taurus.
Moon is 377 332 km (234 463 mi) away from Earth on this date. Moon moves closer next 6 days until perigee, when Earth-Moon distance will reach 368 418 km (228 924 mi).
9 days after its ascending node on 4 December 2015 at 18:33 in ♍ Virgo, the Moon is following the northern part of its orbit for the next 4 days, until it will cross the ecliptic from North to South in descending node on 18 December 2015 at 15:13 in ♓ Pisces.
9 days after beginning of current draconic month in ♍ Virgo, the Moon is moving from the beginning to the first part of it.
2 days after previous South standstill on 12 December 2015 at 08:15 in ♑ Capricorn, when Moon has reached southern declination of ∠-18.438°. Next 10 days the lunar orbit moves northward to face North declination of ∠18.444° in the next northern standstill on 25 December 2015 at 07:30 in ♋ Cancer.
After 10 days on 25 December 2015 at 11:11 in ♋ Cancer, the Moon will be in Full Moon geocentric opposition with the Sun and this alignment forms next Sun-Earth-Moon syzygy. | 0.83659 | 3.162712 |
On April 13, 1905, Italian experimental physicist Bruno Benedetto Rossi was born. Rossi made major contributions to particle physics and the study of cosmic rays. He was one of the first to use rockets to study cosmic rays above the Earth‘s atmosphere. Finding X-rays from space he became the grandfather of high energy astrophysics, being largely responsible for starting X-ray astronomy, as well as the study of interplanetary plasma.
“In any case, whenever technical progress opened a new window into the surrounding world, I felt the urge to look through this window, hoping to see something unexpected.” Bruno Benedetto Rossi
Bruno Rossi – Early Years
Rossi was born to a Jewish family in Venice, Italy, as the eldest of three sons of Rino Rossi, an electrical engineer, who participated in the electrification of Venice, and Lina Minerbi. Rossi was tutored at home until the age of fourteen, after which he attended the Ginnasio and the Liceo in Venice. Then, he began his university studies at the University of Padua and received a Laurea in Physics in 1927 from the University of Bologna. In 1928, Rossi began his career at the University of Florence, as assistant to Antonio Garbasso, who founded the University’s Physics Institute in 1920.
In search of pioneering research, Rossi turned his attention to cosmic rays, which had been discovered by Victor Hess in manned balloon flights in 1911 and 1912. He had read the paper of Walter Bothe and Walter Kohlhörster, who reported the discovery of charged particles that penetrated 4.1 cm of gold, at a time when the most penetrating charged particles known were beta-decay electrons, which could be stopped by less than a millimeter of gold. The penetrating particles were clearly related to the “Höhenstrahlung” discovered by Victor Hess.[3,4] During the 1920s Robert Millikan had made extensive measurements of the ionization produced by the mysterious radiation, which he renamed “cosmic rays.” He proposed that they were photons created as the “birth cries” of the elements formed by the fusion of hydrogen atoms in interstellar space.[3,5] However, Bothe and Kohlhörster’s analysis led them to conclude that the primary radiation itself must also be charged particles, for which independent evidence had been obtained in 1927 by Jacob Clay, who measured a small variation in the rate of ionization produced by cosmic rays with a change in geographic latitude.
The Electronic Coincidence Circuit
After reading the Bothe and Kohlhörster paper, Rossi invented and published in Nature the design of an electronic coincidence circuit, which was a fundamental electronic device for studying high-energy nuclear physics and a basic building block of modern computers. Its adaptability to the detection of coincidences among any number of pulses enabled the detection and identification of rare events that produce coincident pulses in several counters in the midst of high rates of background pulses in each counter. By the spring of 1930, Rossi had fabricated Geiger-Müller counters and had carried out several coincidence experiments. He sent his results to Bothe, who invited him to visit his Berlin laboratory, where he carried out an improved version of the Bothe and Kohlhörster experiment, detecting cosmic-ray particles that traversed 9.7 cm of lead. A plot of the triple coincidences as a function of the amount of the lead above the counters against the lead’s thickness, which came to be known as the Rossi curve, showed a rapid rise as the lead layer was increased, followed by a slow decline.
Components of Cosmic Rays
These experiments showed that ground-level cosmic rays consist of two components: a “soft” component which is capable of prolific generation of multiple particle events, and a “hard” component which is capable of traversing great thicknesses of lead. At Fermi’s invitation, Rossi delivered the introductory talk the Rome international conference on nuclear physics in 1931. Before an audience that included Millikan and Arthur Compton, Rossi outlined his reasons for doubting Millikan’s theory. Millikan definitely was not pleased by the presentation of evidence that most observed cosmic rays are energetic charged particles.
The East-West Effect
In 1932, Rossi was appointed professor of experimental physics at the University of Padua. In 1933, Rossi was able to complete an experiment on the East-West effect. Because this effect is more prominent near the equator, he organised an expedition to Asmara in Eritrea. With Sergio De Bennedetti, he set up a “cosmic ray telescope”, which consisted of two separated Geiger Müller counters in coincidence, whose axis of maximum sensitivity could be pointed in any direction. It soon became apparent that cosmic ray intensity from the West was significantly larger than that from the East. This meant that there was a larger influx of positive primary particles than of negative ones. At the time, this result was surprising, because most investigators held the preconceived notion that the primaries would be negative electrons.
Extensive Cosmic Ray Showers
Also in Eritrea, Rossi discovered another phenomenon: extensive cosmic ray air showers. The discovery occurred during tests to determine the rate of accidental coincidences between the Geiger counters of his detector. To assure that no single particle could trigger the counters he spread them out in a horizontal plane. In this configuration, the frequency of coincidences was greater than that calculated on the basis of the individual rates and the resolving time of the coincidence circuit.
Cosmic Ray Theory
Because both Rossi and his wife Nora were Jewish, they became apprehensive as Italy’s antisemitism grew under the influence of Nazi Germany, and left Italy in September 1938 for Copenhagen, where the Danish physicist, Niels Bohr, had invited him to study. Soon after, Rossi received an invitation to come to the University of Manchester, where Rossi spent a brief but very productive time. By invitation of Compton, Rossi left Europe and went to the University of Chicago to work as a research associate. The following year he was appointed an associate professor at Cornell University. At Cornell, Rossi met his first American graduate student, Kenneth Greisen, with whom he wrote an article, “Cosmic-Ray Theory“, which was published in the Reviews of Modern Physics and became known among cosmic-ray researchers as “The Bible”.
World War II and Los Alamos
In 1942, while commuting from Ithaca to Cambridge, Massachusetts, he became a consultant on radar development at the Radiation Laboratory of the Massachusetts Institute of Technology. Here, along with Greisen, he invented a “range tracking circuit”, which was patented after the war. He left Cornell in 1943 to work at Los Alamos, where the laboratory’s director, Robert Oppenheimer, asked Rossi to form a group to develop diagnostic instruments needed to create the atomic bomb. Bomb development called for large detectors of ionising radiation, whose response is proportional to the energy released in the detector and follows rapid changes in radiation intensity.
After the war, within the new MIT Laboratory for Nuclear Science, Rossi was delegated to create a cosmic ray research group. In 1958 he focused attention on the direct measurements of ionized interplanetary gas using space probes. In 1961 he and his associates constructed a detector that was put on the Explorer X satellite. It discovered the magnetopause, the space boundary beyond which Earth’s magnetic field loses its dominance. In 1963 he also started an exploratory search for cosmic x-rays that resulted in the discovery of the strong Scorpio X-ray source. It was the first known source to be observed outside the solar system. This discovery launched the introduction of X-ray astronomy that serves as a principal tool for astrophysics research. In 1966 he received the rank of Institute Professor that was reserved for scholars of special distinction.
Rossi retired from MIT in 1970. From 1974 to 1980 he taught at the University of Palermo. Among many other prizes, in 1987 he was awarded the Wolf Prize in Physics for his role in the development of X-ray astronomy. Bruno Rossi died from a cardiac arrest at his home in Cambridge on 21 November 1993 at age 88.
At yovisto academic video search, you may learn more about “Cosmic Radiation – a showstopper for space exploration?” in a lecture by Marco Durante
References and Further Reading:
- Jay Bitterman: Astronomy Bio…Bruno Rossi, The Lake County Astronomical Society
- Victor Franz Hess and the Cosmic Radiation, yovisto blog, August 7, 2014.
- Bruno Benedetto Rossi, Proc. of the American Philosophical Society, Vol 144, No. 3, Sep. 2000.
- Victor Hess and the Ultra Radiation, SciHi Blog
- Robert Millikan and the Millikan experiment, SciHi Blog
- Niels Bohr and the beginnings of Quantum Mechanics, SciHI Blog
- Bruno Rossi at Wikidata
- Timeline for Bruno Rossi, via Wikidata | 0.823002 | 3.879564 |
Kepler Space Telescope Current Affairs - 2020
Scientists have discovered cache over 100 new exoplanets using data from NASA’s Kepler Space telescope (KST) as well as ground-based observatories. Exoplanet also called as extrasolar planet, is planet that orbits star other than Sun. The discovery of 100 new exoplanets is expected to play large role in developing research field of exoplanets and life in universe.
Kepler Space Telescope
KST is an unmanned space observatory launched in 2009 by National Aeronautics and Space Administration (NASA). It was tasked with determining how many Earth-like planets occur throughout the Milky Way galaxy.
It was designed for statistical mission and not to probe into environmental conditions of planets that exist in so-called Goldilocks zone (Habitable zone) of their stars. It finds planets by using transit method. It is detection of tiny brightness dips caused by planet after it crosses its host star’s face from spacecraft’s perspective. Transit method technique requires extremely precise pointing of spacecraft.
KST had experienced mechanical trouble in 2013, which led to successor mission called K2. Astronomers around the world are competing to confirm exoplanets suggested by K2 data. NASA had retired KST in November 2018 after it ran out of fuel needed for further science operations. In its mission lifespan of nine-and-a-half year, it had discovered over 2,600 intriguing exoplanets from outside our solar system some of which may harbour life.
Tags: Exoplanets • Kepler Space Telescope • NASA • Science and Technology
NASA has retired Kepler space telescope after it ran out of fuel needed for further science operations. This brings end of nine-and-a-half year mission of Kepler space telescope in which it had discovered over 2,600 intriguing exoplanets from outside our solar system some of which may harbour life.
Kepler space telescope
The unmanned space telescope was launched in 2009 on 3.5-year mission (from 2009 until November 2012), but operated for 9 years. It was NASA’s first planet-hunting mission. It was named after German mathematician and astronomer Johannes Kepler. During its over nine years life, Kepler had observed 530,506 stars and detected 2,662 planets. It used transit photometry detection method for searching for exoplanet, which looked for periodic, repetitive dips in visible light of stars caused by planets passing or transiting in front in front of its host star. The telescope had suffered mechanical failure in 2013. But it was made functional by changing its field of view periodically. This had paved way for K2 mission. | 0.860296 | 3.186211 |
10 strange facts you didn’t know about the Moon. What created the Moon? And what are moonquakes?
1. The Moon is Earth’s only permanent natural satellite
It is the fifth-largest natural satellite in the Solar System, and the largest among planetary satellites relative to the size of the planet that it orbits.
2. The Moon is the second-densest satellite
Among those whose densities are known anyway. The first densest is Jupiter’s satellite Io.
3. The Moon always shows Earth the same face
The Moon is in synchronous rotation with Earth. Its near side is marked by large dark plains (volcanic ‘maria’) that fill the spaces between the bright ancient crustal highlands and the prominent impact craters.
4. The Moon’s surface is actually dark
Although compared to the night sky it appears very bright, with a reflectance just slightly higher than that of worn asphalt. Its gravitational influence produces the ocean tides, body tides, and the slight lengthening of the day.
5. The Sun and the Moon are not the same size
From Earth, both the Sun and the Moon look about same size. This is because, the Moon is 400 times smaller than the Sun, but also 400 times closer to Earth.
6. The Moon is drifting away from the Earth
The Moon is moving approximately 3.8 cm away from our planet every year.
7. The Moon was made when a rock smashed into Earth
The most widely-accepted explanation is that the Moon was created when a rock the size of Mars slammed into Earth, shortly after the solar system began forming about 4.5 billion years ago.
8. The Moon makes the earth move as well as the tides
Everyone knows that the Moon is partly responsible for causing the tides of our oceans and seas on Earth, with the Sun also having an effect. However, as the Moon orbits the Earth it also causes a tide of rock to rise and fall in the same way as it does with the water. The effect is not as dramatic as with the oceans but nevertheless, it is a measurable effect, with the solid surface of the Earth moving by several centimetres with each tide.
9. The Moon has quakes too
They’re not called earthquakes but moonquakes. They are caused by the gravitational influence of the Earth. Unlike quakes on Earth that last only a few minutes at most, moonquakes can last up to half an hour. They are much weaker than earthquakes though.
10. There is water on the Moon!
This is in the form of ice trapped within dust and minerals on and under the surface. It has been detected on areas of the lunar surface that are in permanent shadow and are therefore very cold, enabling the ice to survive. The water on the Moon was likely delivered to the surface by comets. | 0.838164 | 3.364218 |
TRAPPIST-1 System Planets Potentially Habitable
Two exoplanets in the TRAPPIST-1 system have been identified as most likely to be habitable, a paper by PSI Senior Scientist Amy Barr says.
The TRAPPIST-1 system has been of great interest to observers and planetary scientists because it seems to contain seven planets that are all roughly Earth-sized, Barr and co-authors Vera Dobos and Laszlo L. Kiss said in “Interior Structures and Tidal Heating in the TRAPPIST-1 Planets” that appears in Astronomy & Astrophysics.
“Because the TRAPPIST-1 star is very old and dim, the surfaces of the planets have relatively cool temperatures by planetary standards, ranging from 400 degrees Kelvin (260 degrees Fahrenheit), which is cooler than Venus, to 167 degrees Kelvin (-159 degrees Fahrenheit), which is colder than Earth’s poles,” Barr said. “The planets also orbit very close to the star, with orbital periods of a few days. Because their orbits are eccentric –not quite circular – these planets could experience tidal heating just like the moons of Jupiter and Saturn.”
“Assuming the planets are composed of water ice, rock, and iron, we determine how much of each might be present, and how thick the different layers would be. Because the masses and radii of the planets are not very well-constrained, we show the full range of possible interior structures and interior compositions.” Barr said. The team’s results show that improved estimates of the masses of each planet can help determine whether each of the planets has a significant amount of water.
The planets studied are referred to by letter, planets b through h, in order of their distance from the star. Analyses performed by co-author Vera Dobos show that planets d and e are the most likely to be habitable due to their moderate surface temperatures, modest amounts of tidal heating, and because their heat fluxes are low enough to avoid entering a runaway greenhouse state. A global water ocean likely covers planet d.
The team calculated the balance between tidal heating and heat transport by convection in the mantles of each planet. Results show that planets b and c likely have partially molten rock mantles. The paper also shows that planet c likely has a solid rock surface, and could have eruptions of silicate magmas on its surface driven by tidal heating, similar to Jupiter’s moon Io. | 0.866046 | 3.770293 |
November 23, 2016 – A snapshot of the stellar life cycle has been captured in a new portrait from NASA’s Chandra X-ray Observatory and the Smithsonian’s Submillimeter Array (SMA). A cloud that is giving birth to stars has been observed to reflect X-rays from Cygnus X-3, a source of X-rays produced by a system where a massive star is slowly being eaten by its companion black hole or neutron star. This discovery provides a new way to study how stars form.
In 2003, astronomers used Chandra’s high-resolution X-ray vision to find a mysterious source of X-ray emission located very close to Cygnus X-3. The separation of these two sources on the sky is equivalent to the width of a penny at a distance of 830 feet away. In 2013, astronomers reported that the new source is a cloud of gas and dust.
In astronomical terms, this cloud is rather small – about 0.7 light years in diameter. Astronomers realized that this cloud was acting as a mirror, reflecting some of the X-rays generated by Cygnus X-3 towards Earth.
“We nicknamed this object the ‘Little Friend’ because it is a faint source of X-rays next to a very bright source that showed similar X-ray variations,” said Michael McCollough of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts, who led the most recent study of this system.
The Chandra observations reported in 2013 suggested that the Little Friend had a mass between two and 24 times that of the Sun. This suggested that the cloud was a “Bok globule,” a small dense cloud where infant stars can be born. However, more evidence was needed.
To determine the nature of the Little Friend, astronomers used the SMA, a series of eight radio dishes atop Mauna Kea in Hawaii. The SMA found molecules of carbon monoxide, an important clue that the Little Friend is indeed a Bok globule. Also, the SMA data reveals the presence of a jet or outflow within the Little Friend, an indication that a star has started to form inside.
“Typically, astronomers study Bok globules by looking at the visible light they block or the radio emission they produce,” said co-author Lia Corrales of the Massachusetts Institute of Technology in Cambridge, Mass. “With the Little Friend, we can examine this interstellar cocoon in a new way using X-rays – the first time we have ever been able to do this with a Bok globule.”
At an estimated distance of almost 20,000 light years from Earth, the Little Friend is also the most distant Bok globule yet seen.
The properties of Cygnus X-3 and its proximity to the Little Friend also give an opportunity to make a precise distance measurement – something that is often very difficult in astronomy. Since the early 1970s, astronomers have observed a regular 4.8-hour variation in the X-rays from Cygnus X-3. The Little Friend, acting as an X-ray mirror, shows the same variation, but slightly delayed because the path the reflected X-rays take is longer than a straight line from Cygnus X-3 to Earth.
By measuring the delay time in the periodic variation between Cygnus X-3 and the Little Friend, astronomers were able to calculate the distance from Earth to Cygnus X-3 of about 24,000 light years.
Because Cygnus X-3 contains a massive, short-lived star, scientists think it must have originated in a region of the Galaxy where stars are still likely to be forming. These regions are only found in the Milky Way’s spiral arms. However, Cygnus X-3 is located outside any of the Milky Way’s spiral arms.
“In some ways it’s a surprise that we find Cygnus X-3 where we do,” said co-author Michael Dunham of CfA and the State University of New York at Fredonia. “We realized something rather unusual needed to happen during its early years to send it on a wild ride.”
The researchers suggest that the supernova explosion that formed either the black hole or neutron star in Cygnus X-3 kicked the binary system away from its original birthplace. Assuming that Cygnus X-3 and the Little Friend formed near each other, they estimate that Cygnus X-3 must have been thrown out at speeds between 400,000 and 2 million miles per hour.
A paper describing these results appeared in a recent issue of The Astrophysical Journal Letters and is available online.
NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.
An interactive image, a podcast, and a video about the findings are available at: | 0.877658 | 3.929719 |
SMART-1’s detection of calcium, iron and other elements on the Moon. Image credit: ESA. Click to enlarge.
Thanks to measurements by the D-CIXS X-ray spectrometer, ESA?s SMART-1 spacecraft has made the first ever unambiguous remote-sensing detection of calcium on the Moon.
SMART-1 is currently performing the verification and calibration of its instruments, while it runs along its science orbit, reaching 450 kilometres from the Moon at its closest distance. During this calibration phase, which precedes the actual science observations phase, the SMART-1 scientists are getting acquainted with the delicate operations and the performance of their instruments in the warm environment of the lunar orbit.
Although it is still preparing for full lunar operations, D-CIXS has started already sending back high-quality data. D-CIXS is designed to measure the global composition of the Moon by observing how it glows in X-rays when the Sun shines on it. In fact, different chemical elements provide their ‘fingerprinting’, each glowing in a unique way.
On 15 January 2005, between 07:00 and about 09:00 Central European Time, a solar flare occurred, blasting a quantity of radiation that flooded the Solar System and the Moon. “The Sun was kind to us”, said Prof Manuel Grande of the Rutherford Appleton Laboratory, leader of the D-CIXS instrument team. “It set off a large X-ray flare just as we took our first look downwards at the lunar surface”.
The lunar surface reacts to the incoming solar radiation by glowing in different X-ray wavelengths. This enabled D-CIXS, , to distinguish the presence of chemical elements – including calcium, aluminium, silicon and iron – in Mare Crisium, the area of the lunar surface being observed at that moment. “It is the first time ever that calcium has been unambiguously detected on the Moon by remote-sensing instrumentation”, added Prof. Grande. Calcium is an important rock-forming element on the Moon.
“Even before our scientists have finished setting up the instruments, SMART-1 is already producing brand new lunar science”, said Bernard Foing, SMART-1 Project Scientist. “When we get D-CIXS and the other instruments fully tuned, with scientific data rolling in routinely, we should have a truly ground-breaking mission”.
Original Source: ESA News Release | 0.822441 | 3.542047 |
April 2020 (a few days after a Pluto retrograde)
It should have been named Proserpina, goddess of the underworld and death-to-life renewal. The ancient Greeks knew her as Persephone.
Perhaps it will seem strange that a terrapsychologist—someone who studies how the things of the world, natural or otherwise, show up as presences inside us—occasionally stares up at the sky. However, the split between heavens and Earth is relatively recent, historically speaking, and by no means universal. Nature-celebrating cultures appreciatively watch the cycling stars as well as the soils, winds, and seas. Perhaps we should too.
I will root my argument in five observations familiar to some of us—including broad-minded scientists*—through lived encounters, but seldom if ever acknowledged by the materialist ideology of scientism:
- The relationship between planetary and earthly events are synchronistic rather than causal (C. G. Jung), which places them in the realm of storytelling and meaning-making. (To say it academically, we are working here with hermeneutics, not empirics; qualities, not quantities.)
- Meanings of personal names often link synchronistically to events of discovery.
- What we give mythological names to tend to exhibit mythic qualities (terrapsychology): the reverse of psychological projection theory, which assumes a human influence over everything we perceive.
- Myths don’t stay in myth books: they roam at will like blobs of collective psyche in search of retellings, even influencing the means by which we employ them (see my book Myths Among Us).
- The planet names in both Western astrology and astronomy show a masculinist bias in need of correction.
* Kripal, J. (2919). The Flip: Epiphanies of Mind and the Future of Knowledge.Let me begin, briefly, with what brought all this to the surface for me.
Beginning: Proserpina Approaches
To oversimplify somewhat with an anecdote:
Four years ago, Pluto began “his” approach to my natal South Node, which lies just beneath my Descendant in Capricorn. North and South Lunar Nodes are where the traveling Moon crosses the plane of the ecliptic, the planet along which the other planets move as seen from Earth. (In astrology, “planets” include Sun and Moon.) The South Node symbolizes where we come from, basic security issues, lessons from the past, traits we hang on to. Where we start out from; the North Node indicates where we need to go. In Capricorn, the South Node wears themes of overwork, overachievement, and reluctance to depend on others. In House 6, these also show up in work and health.
The Descendant involves close relationships; in Capricorn, this can mean partners who are self-contained, serious, and ambitious. It is also where the Sun sets on its daily journey into the underworld.
Pluto intensifies what it touches. It brings the dramatic and transformative motif of death-and-rebirth. Pluto can also signal the entry of shadowy underworld figures onto life’s stage.
As Pluto reached my South Node and then my Descendant, with Saturn following close by, upheavals multiplied, beginning with my exiting one life myth (= overarching story) and walking into another. This altered several long-term goals. The workplace I had entered with such high hopes turned out to be riddled with conflicts of interest, ego, and power, prompting me to leave in deep disillusionment. The suddenly revealed deceits of a secretly ambitious partner ended a relationship. My adoptive and birth fathers died within a year of each other. A close friend was diagnosed with thyroid cancer. My mother’s savings were stolen by a long-trusted aide.
Throughout these disruptions, I dreamed continually not of Pluto, but of Persephone: beckoning me, embracing me, pacing outside my dad’s home months before he died. After this series of inner and outer deaths I understood why Odysseus, who had entered the underworld in dark foreboding, had referred to her as the “iron queen.” Only after most of the turbulence had passed did I think to connect Persephone to the astrological parallels of that time.
These connections are relevant to my interest because of their “meaningful coincidence” quality. I am not aware of convincing evidence that Pluto or any other planet directly influences life down here. Celestial symbols are not causes.
All this made me curious about why this planet of mythic intensification was named Pluto (“wealth”) and not Proserpina.
Underworld Motifs in Pluto’s Discovery
Percival (“pierce”) Lowell (“young wolf”) was no stranger to wealth. Born in the spring into a rich Bostonian family, he trained in science and mathematics at Harvard, ran a profitable cotton mill, and served in various political appointments, including foreign secretary. He purchased his own astronomical instruments and used his money to found the observatory named after him.
Lowell was of the sort who sometimes enjoyed serendipitous accomplishments through mythological mistake-making. He was sure about the fictional canals on Mars, for instance, and the spoked shape he saw on Venus was a glassy reflection of his own inquisitive eye. Then he convinced himself that an undiscovered Planet X was warping the orbits of Uranus and Neptune. This proved unfounded, but it did point him in the right stellar direction, a fact later put down to coincidence. Unknown to him, he had captured very faint images of well-hidden Pluto twice in 1915. The underworld claimed him the following year.
Pluto hid through a decade of financial battling between reclusive real estate speculator Constance Savage Lowell and the observatory named after her departed husband. Then 22-year-old Clyde (“river” in Scotland) Tombaugh (“by the creek”) emerged from an Illinois farm bearing impressive astronomical sketches and a desire to find Planet X. To do this he used a blink comparator: a device for showing image displacements between pairs of photographs. On February 18th, 1930, he noticed one such moving image in the constellation Gemini. The discovery of the new dwarf planet was announced on March 13th, Percival Lowell’s birthday and the day of William Herschel’s discovery of Uranus.
Despite her fight to defund the observatory, Constance Lowell took it upon herself to pitch three names for the new heavenly body: Zeus, Percival, and Constance.
Venetia (“good hound” or “fair, white”) Burney (“island of the brook”), a schoolgirl in Oxford, offered the name Pluto for the cold, dark, distant world. “Pluto” kept to the Roman deity naming tradition, and first two letters reminded the official choosers of Lowell’s initials. They announced their decision on May 1st, 1930. Astronomer Carl Lampland made the first spoken announcement, in Ashurst Hall at Northern Arizona U (current name), but the acoustics were bad and few heard his quiet voice.
In the first edition of Archai: The Journal of Archetypal Cosmology, Richard Tarnas, author of Cosmos and Psyche, had this to say about the synchronistic timing of all this:
With respect to Pluto’s discovery, the synchronistic phenomena in the decades immediately surrounding 1930, and more generally in the twentieth century, include the splitting of the atom and the unleashing of nuclear power; the titanic technological empowerment of modern industrial civilization and military force; the rise of fascism and other mass movements; the widespread cultural influence of evolutionary theory and psychoanalysis with their focus on the biological instincts; increased sexual and erotic expression in social mores and the arts; intensified activity and public awareness of the criminal underworld; and a tangible intensification of instinctually driven mass violence and catastrophic historical developments, evident in the world wars, the holocaust, and the threat of nuclear annihilation and ecological devastation. Here also can be mentioned the intensified politicization and power struggles characteristic of twentieth-century life, the development of powerful forms of depth-psychological transformation and catharsis, and the scientific recognition of the entire cosmos as a vast evolutionary phenomenon from the primordial fireball to the still-evolving present.
Anecdote aside, can we detect the presence of the underworld goddess in any of these events?
At first, “Pluto” seems the right name, thematically, for the cold world so far from our own. Surface temperature: an average of -229 Celsius (-380 Fahrenheit). From that surface, our sun is but a luminous speck four billion miles away—but on average, because Pluto has the most elliptical (and tilted) orbit of any planet, at one point passing inside the orbit of Neptune. The path of Proserpina shares a similar looping: half the year in the underworld, half above it.
The story goes that one day the young woman was out gathering flowers near a lake when Pluto emerged from a volcano. Struck by love arrow ordered by Venus and shot by her son Cupid, the chariot-riding god seized her and dragged her under.
Her mother Ceres searched for but could not find her, just a belt floating on a lake of tears. Her pleading with the other gods struck a new balance: Proserpina would spend the months of cold in the underworld and those of flowering plants in the upper. From that point onward, she ruled the underground realm of death with Pluto. In many tales, she is the active partner who meets those who arrive.
Looking again at the list of plutonic synchronicities assembled by Tarnas (above) from a Proserpina perspective, many seem to involve violence against the innocent and the undeserving, including destruction of the natural world. We might add that in 1930, the Great Plains of the U.S. went into the kind of drought caused by grieving Ceres, migrating everywhere to look for lost Proserpina, her sorrowing earth mother’s wandering footsteps imprinting deserts on the land. This agricultural catastrophe in turn fed the Great Depression. Crises rampant throughout the 1930s culminated in World War II.
Tarnas also points out that the astrological qualities of Pluto echo those of Dionysus, associated by the ancient Greeks with Hades:
…The planet Pluto is also linked to Nietzsche’s Dionysian principle and the will to power and to Schopenhauer’s blind striving universal will—all these embodying the powerful forces of nature and emerging from nature’s chthonic depths, within and without, the intense, fiery elemental underworld.
Will would not be a quality necessarily associated, at least in myth, with quiet Pluto, who tended to hide away and let things run (down) themselves. Perhaps Constance Lowell expressed a bit of blind will while pretending to be sightless in order to get her way. Be that as it may, the name of willful, assertive Proserpina points back to the Latin proserpere: “to emerge,” which she does every year. Also, she harks back to the Roman goddess Libera (Proserpina/Libera: PL), wife of Liber, the Roman Dionysus, with whom she shared wild libidinal festivals. She was his feminine half, her free spirit fusing and exploding in worldwide movements of liberation.
The astrological glyph for Pluto unintentionally recalls a blossom seen from the side. Proserpina had picked one shortly before landing in the underworld. The lake near where she had dallied, the water in the names of the various astronomers, and the rivers in the underworld are thematically one. The time of discovery and announcement was the spring season, when Proserpina announces herself by emerging into the light.
Perhaps her abduction initially seemed like a kind of demotion. Certainly it seemed that way for Pluto, which in 2006 was reduced by the International Astronomical Union from planet to dwarf planet. At that time Pluto stood retrograde in Sagittarius, a sign of reassessment and far-reaching decisions. In a chart drawn at the time and place of the meeting, Pluto occupied House 1: how you appear to others.
To be a planet, astronomically, you must clear the space around your orbit and stay in your lane. Pluto did neither. Also, Eris, a dwarf planet discovered in 2005, was found to hold more mass than Pluto. The resulting controversy recalled the Eris of myth as a deity of discord. It was as though Pluto as world was no longer needed in the heavens, what with the industrially driven conversion of so much of Earth’s surface into an ecologically barren underworld.
Most astrologers ignored this demotion. Comparisons between life events and Pluto’s movements convinced them that the chronological parallels assembled since 1930 were valid.
Furthermore, an asteroid had been promoted: Ceres, mother of Proserpina, now a dwarf planet.
This may be the final scientific say on Pluto’s status as planet, but it will not be Proserpina’s. I expect her to keep surfacing, synchronistically and in other ways. Perhaps the underlying issue is collective acceptance of transformation, death, and rebirth. When our consciousness catches up with what she signals to us, new openings in it will allow to her reappear.
Incidentally, Pluto is orbited by the moon Charon, named after the ferryman of Hades. If Pluto is ever renamed Proserpina, perhaps Charon should be renamed Pluto? Symbolically speaking, is the dark northern polar cap the invisibility hat of Hades? The science team of the New Horizons probe that passed these worlds in 2015 informally named the cap Mordor.
Perhaps the most evocative discovery made by this probe arrived in a high-resolution image: a thousand kilometers of nitrogen ice cast in the shape of a giant heart renewed invisibly from below. | 0.911141 | 3.029523 |
In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force may be applied to cause a linear acceleration without an angular acceleration. Calculations in mechanics are often simplified when formulated with respect to the center of mass. It is a hypothetical point where the entire mass of an object may be assumed to be concentrated to visualise its motion. In other words, the center of mass is the particle equivalent of a given object for application of Newton's laws of motion.
In the case of a single rigid body, the center of mass is fixed in relation to the body, and if the body has uniform density, it will be located at the centroid. The center of mass may be located outside the physical body, as is sometimes the case for hollow or open-shaped objects, such as a horseshoe. In the case of a distribution of separate bodies, such as the planets of the Solar System, the center of mass may not correspond to the position of any individual member of the system.
The center of mass is a useful reference point for calculations in mechanics that involve masses distributed in space, such as the linear and angular momentum of planetary bodies and rigid body dynamics. In orbital mechanics, the equations of motion of planets are formulated as point masses located at the centers of mass. The center of mass frame is an inertial frame in which the center of mass of a system is at rest with respect to the origin of the coordinate system.
The concept of "center of mass" in the form of the center of gravity was first introduced by the great ancient Greek physicist, mathematician, and engineer Archimedes of Syracuse. He worked with simplified assumptions about gravity that amount to a uniform field, thus arriving at the mathematical properties of what we now call the center of mass. Archimedes showed that the torque exerted on a lever by weights resting at various points along the lever is the same as what it would be if all of the weights were moved to a single point--their center of mass. In work on floating bodies he demonstrated that the orientation of a floating object is the one that makes its center of mass as low as possible. He developed mathematical techniques for finding the centers of mass of objects of uniform density of various well-defined shapes.
Later mathematicians who developed the theory of the center of mass include Pappus of Alexandria, Guido Ubaldi, Francesco Maurolico,Federico Commandino,Simon Stevin,Luca Valerio,Jean-Charles de la Faille, Paul Guldin,John Wallis, Louis Carré, Pierre Varignon, and Alexis Clairaut.
The center of mass is the unique point at the center of a distribution of mass in space that has the property that the weighted position vectors relative to this point sum to zero. In analogy to statistics, the center of mass is the mean location of a distribution of mass in space.
In the case of a system of particles Pi, i = 1, ..., n , each with mass mi that are located in space with coordinates ri, i = 1, ..., n , the coordinates R of the center of mass satisfy the condition
Solving this equation for R yields the formula
where M is the sum of the masses of all of the particles.
If the mass distribution is continuous with the density ?(r) within a solid Q, then the integral of the weighted position coordinates of the points in this volume relative to the center of mass R over the volume V is zero, that is
Solve this equation for the coordinates R to obtain
where M is the total mass in the volume.
The coordinates R of the center of mass of a two-particle system, P1 and P2, with masses m1 and m2 is given by
Let the percentage of the total mass divided between these two particles vary from 100% P1 and 0% P2 through 50% P1 and 50% P2 to 0% P1 and 100% P2, then the center of mass R moves along the line from P1 to P2. The percentages of mass at each point can be viewed as projective coordinates of the point R on this line, and are termed barycentric coordinates. Another way of interpreting the process here is the mechanical balancing of moments about an arbitrary point. The numerator gives the total moment that is then balanced by an equivalent total force at the center of mass. This can be generalized to three points and four points to define projective coordinates in the plane, and in space, respectively.
For particles in a system with periodic boundary conditions two particles can be neighbours even though they are on opposite sides of the system. This occurs often in molecular dynamics simulations, for example, in which clusters form at random locations and sometimes neighbouring atoms cross the periodic boundary. When a cluster straddles the periodic boundary, a naive calculation of the center of mass will be incorrect. A generalized method for calculating the center of mass for periodic systems is to treat each coordinate, x and y and/or z, as if it were on a circle instead of a line. The calculation takes every particle's x coordinate and maps it to an angle,
where xmax is the system size in the x direction and . From this angle, two new points can be generated, which can be weighted by the mass of the particle for the center of mass or given a value of 1 for the geometric center:
In the plane, these coordinates lie on a circle of radius 1. From the collection of and values from all the particles, the averages and are calculated.
where M is the sum of the masses of all of the particles.
These values are mapped back into a new angle, , from which the x coordinate of the center of mass can be obtained:
The process can be repeated for all dimensions of the system to determine the complete center of mass. The utility of the algorithm is that it allows the mathematics to determine where the "best" center of mass is, instead of guessing or using cluster analysis to "unfold" a cluster straddling the periodic boundaries. If both average values are zero, , then is undefined. This is a correct result, because it only occurs when all particles are exactly evenly spaced. In that condition, their x coordinates are mathematically identical in a periodic system.
A body's center of gravity is the point around which the resultant torque due to gravity forces vanishes. Where a gravity field can be considered to be uniform, the mass-center and the center-of-gravity will be the same. However, for satellites in orbit around a planet, in the absence of other torques being applied to a satellite, the slight variation (gradient) in gravitational field between closer-to (stronger) and further-from (weaker) the planet can lead to a torque that will tend to align the satellite such that its long axis is vertical. In such a case, it is important to make the distinction between the center-of-gravity and the mass-center. Any horizontal offset between the two will result in an applied torque.
It is useful to note that the mass-center is a fixed property for a given rigid body (e.g. with no slosh or articulation), whereas the center-of-gravity may, in addition, depend upon its orientation in a non-uniform gravitational field. In the latter case, the center-of-gravity will always be located somewhat closer to the main attractive body as compared to the mass-center, and thus will change its position in the body of interest as its orientation is changed.
In the study of the dynamics of aircraft, vehicles and vessels, forces and moments need to be resolved relative to the mass center. That is true independent of whether gravity itself is a consideration. Referring to the mass-center as the center-of-gravity is something of a colloquialism, but it is in common usage and when gravity gradient effects are negligible, center-of-gravity and mass-center are the same and are used interchangeably.
In physics the benefits of using the center of mass to model a mass distribution can be seen by considering the resultant of the gravity forces on a continuous body. Consider a body Q of volume V with density ?(r) at each point r in the volume. In a parallel gravity field the force f at each point r is given by,
where dm is the mass at the point r, g is the acceleration of gravity, and k is a unit vector defining the vertical direction. Choose a reference point R in the volume and compute the resultant force and torque at this point,
If the reference point R is chosen so that it is the center of mass, then
which means the resultant torque T=0. Because the resultant torque is zero the body will move as though it is a particle with its mass concentrated at the center of mass.
By selecting the center of gravity as the reference point for a rigid body, the gravity forces will not cause the body to rotate, which means the weight of the body can be considered to be concentrated at the center of mass.
The linear and angular momentum of a collection of particles can be simplified by measuring the position and velocity of the particles relative to the center of mass. Let the system of particles Pi, i=1,...,n of masses mi be located at the coordinates ri with velocities vi. Select a reference point R and compute the relative position and velocity vectors,
The total linear and angular momentum vectors relative to the reference point R are
If R is chosen as the center of mass these equations simplify to
where m is the total mass of all the particles, p is the linear momentum, and L is the angular momentum
The Law of Conservation of Momentum predicts that for any system not subjected to external forces the momentum of the system will remain constant, which means the center of mass will move with constant velocity. This applies for all systems with classical internal forces, including magnetic fields, electric fields, chemical reactions, and so on. More formally, this is true for any internal forces that cancel in accordance with Newton's Third Law.
The experimental determination of the center of mass of a body uses gravity forces on the body and relies on the fact that in the parallel gravity field near the surface of the earth the center of mass is the same as the center of gravity.
The center of mass of a body with an axis of symmetry and constant density must lie on this axis. Thus, the center of mass of a circular cylinder of constant density has its center of mass on the axis of the cylinder. In the same way, the center of mass of a spherically symmetric body of constant density is at the center of the sphere. In general, for any symmetry of a body, its center of mass will be a fixed point of that symmetry.
An experimental method for locating the center of mass is to suspend the object from two locations and to drop plumb lines from the suspension points. The intersection of the two lines is the center of mass.
The shape of an object might already be mathematically determined, but it may be too complex to use a known formula. In this case, one can subdivide the complex shape into simpler, more elementary shapes, whose centers of mass are easy to find. If the total mass and center of mass can be determined for each area, then the center of mass of the whole is the weighted average of the centers. This method can even work for objects with holes, which can be accounted for as negative masses.
A direct development of the planimeter known as an integraph, or integerometer, can be used to establish the position of the centroid or center of mass of an irregular two-dimensional shape. This method can be applied to a shape with an irregular, smooth or complex boundary where other methods are too difficult. It was regularly used by ship builders to compare with the required displacement and center of buoyancy of a ship, and ensure it would not capsize.
An experimental method to locate the three-dimensional coordinates of the center of mass begins by supporting the object at three points and measuring the forces, F1, F2, and F3 that resist the weight of the object, ( is the unit vector in the vertical direction). Let r1, r2, and r3 be the position coordinates of the support points, then the coordinates R of the center of mass satisfy the condition that the resultant torque is zero,
This equation yields the coordinates of the center of mass R* in the horizontal plane as,
The center of mass lies on the vertical line L, given by
The three-dimensional coordinates of the center of mass are determined by performing this experiment twice with the object positioned so that these forces are measured for two different horizontal planes through the object. The center of mass will be the intersection of the two lines L1 and L2 obtained from the two experiments.
The characteristic low profile of the U. S. military Humvee was designed in part to allow it tilt farther than taller vehicles, without a rollover, because its low center of mass would stay over the space bounded the four wheels even at angles far from the horizontal.
The center of mass is an important point on an aircraft, which significantly affects the stability of the aircraft. To ensure the aircraft is stable enough to be safe to fly, the center of mass must fall within specified limits. If the center of mass is ahead of the forward limit, the aircraft will be less maneuverable, possibly to the point of being unable to rotate for takeoff or flare for landing. If the center of mass is behind the aft limit, the aircraft will be more maneuverable, but also less stable, and possibly unstable enough so as to be impossible to fly. The moment arm of the elevator will also be reduced, which makes it more difficult to recover from a stalled condition.
For helicopters in hover, the center of mass is always directly below the rotorhead. In forward flight, the center of mass will move forward to balance the negative pitch torque produced by applying cyclic control to propel the helicopter forward; consequently a cruising helicopter flies "nose-down" in level flight.
The center of mass plays an important role in astronomy and astrophysics, where it is commonly referred to as the barycenter. The barycenter is the point between two objects where they balance each other; it is the center of mass where two or more celestial bodies orbit each other. When a moon orbits a planet, or a planet orbits a star, both bodies are actually orbiting a point that lies away from the center of the primary (larger) body. For example, the Moon does not orbit the exact center of the Earth, but a point on a line between the center of the Earth and the Moon, approximately 1,710 km (1,062 miles) below the surface of the Earth, where their respective masses balance. This is the point about which the Earth and Moon orbit as they travel around the Sun. If the masses are more similar, e.g., Pluto and Charon, the barycenter will fall outside both bodies.
Knowing the location of the center of gravity when rigging is crucial, possibly resulting in severe injury or death if assumed incorrectly. A center of gravity that is at or above the lift point will most likely result in a tip-over incident. In general, the further the center of gravity below the pick point, the more safe the lift. There are other things to consider, such as shifting loads, strength of the load and mass, distance between pick points, and number of pick points. Specifically, when selecting lift points, it's very important to place the center of gravity at the center and well below the lift points.
In kinesiology and biomechanics, the center of mass is an important parameter that assists people in understanding their human locomotion. Typically, a human's center of mass is detected with one of two methods: The reaction board method is a static analysis that involves the person lying down on that instrument, and use of their static equilibrium equation to find their center of mass; the segmentation method relies on a mathematical solution based on the physical principle that the summation of the torques of individual body sections, relative to a specified axis, must equal the torque of the whole system that constitutes the body, measured relative to the same axis. | 0.90948 | 3.954707 |
In the southern hemisphere this weekend in the ‘Land of Oz?’ Are you missing out on the passage of Comet 45/P Honda-Mrkos-Pajdušáková, and the penumbral lunar eclipse? Fear not, there’s an astronomical event designed just for you, as the Moon occults (passes in front of) the bright star Regulus on the evening of Saturday, January 11th.
The entire event is custom made for the continent of Australia and New Zealand, occurring under dark skies. Now for the bad news: the waning gibbous Moon will be less than 14 hours past Full during the event, meaning that the ingress (disappearance) of Regulus will occur along its bright leading limb and egress (reappearance) will occur on the dark limb. We prefer occultations during waxing phase, as the star winks out on the dark limb and seems to slowly fade back in on the bright limb.
The International Occultation Timing Association has a complete list of precise ingress/egress times for cities located across the continent. An especially interesting region to catch the event lies along the northern graze line across the sparsely populated Cape York peninsula, just north of Cairns.
The Moon occults Aldebaran and then Regulus six days later during every lunation in 2017. This is occultation number three in a cycle of 19 running from December 18, 2016 to April 24, 2018. The Moon occults Regulus 214 times in the 21st century, and Regulus is currently the closest bright star to the ecliptic plane, just 27′ away.
We’ve also got a very special event just under 14 hours prior, as a penumbral lunar eclipse occurs, visible on all continents… except Australia. Mid-eclipse occurs at 00:45 Universal Time (UT, Saturday morning on February 11th), or 7:45 PM Eastern Standard Time (EST) on the evening of Friday, February 10th, when observers may note a dusky shading on the northern limb of the Moon as the Moon just misses passing through the dark edge of the Earth’s inner umbral shadow. Regulus will sit less than seven degrees off of the lunar limb at mid-eclipse Friday night.
How often does an eclipsed Moon occult a bright star? Well, stick around until over four centuries from now on February 22nd, 2445, and observers based around the Indian Ocean region can watch just such an event, as the eclipsed Moon also occults Regulus. Let’s see, I should have my consciousness downloaded into my second android body by then…
We’ll be streaming the Friday night eclipse live from Astroguyz HQ here in Spring Hill, Florida starting at 7:30 PM EST/00:30 UT, wifi-willing. Astronomer Gianluca Masi of the Virtual Telescope Project will also carry the eclipse live starting at 22:15 UT on the night of Friday, February 10th.
This eclipse also marks the start of eclipse season one of two, which climaxes with an annular eclipse crossing southern Africa and South America on February 26th. The second and final eclipse season of 2017 starts with a partial lunar eclipse on August 7th, which sets us up for the Great American Eclipse crossing the United States from coast to coast on August 21st, 2017.
A lunar occultation of Regulus also provides a shot at a unique scientific opportunity. Spectroscopic measurements suggest that the primary main sequence star possesses a small white dwarf companion, a partner which has never been directly observed. This unseen white dwarf may – depending on the unknown orientation of its orbit – make a brief appearance during ingress or egress for a fleeting split second, when the dark limb of the Moon has covered dazzling Regulus. High speed video might just nab a double step occlusion, as the white dwarf companion is probably about 10,000 times fainter than Regulus at magnitude +11 at the very brightest. Regulus is located 79 light years distant.
Our best results for capturing an occultation of a star or planet by the Moon have always been with a video camera aimed straight through our 8” Schmidt-Cassegrain telescope. The trick is always to keep the star visible in the frame near the brilliant Full Moon. Cropping the Moon out of the field as much as possible can help somewhat. Set up early, to work the bugs out of focusing, alignment, etc. We also run WWV radio in the background for an audible time hack on the video.
The best occultation of Regulus by the Moon for North America in 2017 occurs on October 15th, when the Moon is at waning crescent phase. Unfortunately, the occultation of Regulus by asteroid 163 Erigone back in 2014 was clouded out, though the planet Venus occults the star on October 1st, 2044. Let’s see, by then I’ll be…
Comets and eclipses and occultations, oh my. It’s a busy weekend for observational astronomy, for sure. Consider it an early Valentine’s Day weekend gift from the Universe.
Webcasting the eclipse or the occultation this weekend? Let us know, and send those images of either event to Universe Today’s Flickr forum.
Read about eclipses, occultations and more tales of astronomy in our yearly guide 101 Astronomical Events For 2017, free from Universe Today. | 0.815454 | 3.593557 |
Scientists just discovered a planet out of 'Star Wars'
Visitors to the Hoth-like planet had better bundle up. It's cold out there. Like, really really cold.
There's a scene in "The Empire Strikes Back" that brings chills to movie watchers. Literally.
Watching the sequences that take place on the icy planet Hoth makes a trip to Alaska seem like an exotic getaway. The robot C-3PO is so cold, he remarks, "My joints are freezing up." Well, as it turns out, science fiction is fast becoming science fact. NASA scientists have just discovered a new "iceball" planet that is so cold, it's drawing comparisons to the one from Star Wars.
"While it is covered in ice, at around minus-400 degrees Fahrenheit, it is actually much, much colder than Hoth," said Yossi Shvartzvald, a postdoctoral fellow at NASA's Jet Propulsion Laboratory in California and lead author of a study about the new planet.
Known for now simply as OGLE-2016-BLG-1195Lb, the planet is nearly 13,000 light-years away from Earth. (That's just a hop, skip and a jump for spaceships like Han Solo's Millennium Falcon.) It was discovered by an international team, including scientists from U.S., Korea, Poland and Israel.
At a frigid 76 degrees below zero, the temperature on Hoth was still livable for the 15 species that called it home – including a group of towering predators known as wampas and large gray snow lizards called tauntauns. As for the new planet, "It's hard to imagine any life surviving in such an environment, not humans or tauntauns anyway," joked Shvartzvald, an alumnus of Tel Aviv University in Israel, a markedly warmer locale.
Lately, scientists have been discovering new planets at an impressive clip. Earlier this month, Shvartzvald was on a team that found a "super-Jupiter mass planet." Both finds were made possible thanks to a technique known as microlensing. Based on the gravitational theories of Albert Einstein, it allows astronomers to detect objects that range from the mass of a planet to the mass of a star, regardless of the light they emit.
Ground-based telescopes available today – like the world's largest in Green Bank, W.Va. – are not able to find smaller planets than this one using the microlensing method. Instead, a highly sensitive telescope in space would be needed. NASA's forthcoming Wide Field Infrared Survey Telescope (WFIRST), planned for launch in the mid-2020s, will have this capability.
"One of the problems with estimating how many planets like this are out there is that we have reached the lower limit of planet masses that we can currently detect with microlensing," Shvartzvald said. "WFIRST will be able to change that."
MORE FROM THE GRAPEVINE: | 0.814685 | 3.178214 |
Geoff Marcy remembers the hair standing up on the back of his neck. Paul Butler remembers being dead tired. The two men had just made history: the first confirmation of a planet orbiting another star.
The groundbreaking discovery had been announced less than a week earlier by the European team of Michel Mayor and Didier Queloz. But the news was met with some initial skepticism in the astronomical community. By a stroke of good luck, Marcy and Butler happened to have previously scheduled observation time on a 120-inch telescope at the Lick Observatory, atop California's Mount Hamilton.
The scientists, who would become two of the world's most famous planet hunters, remember driving down the mountainside together in October 1995. They'd spent four straight nights making their observations. And while further processing would be needed to make the scientific case, their data seemed clear and unmistakable -- and almost impossible. A huge planet, at least half the size of Jupiter, was not only orbiting its host star more tightly than Mercury hugs the sun. It was racing around that star, making a complete orbit in just four days.
The planet, called 51 Pegasi b, would open a new era in humanity's exploration of our galactic neighborhood. It would be the first in a series of "hot Jupiters" -- giant planets in fast, tight orbits -- discovered in rapid succession. The rush of new worlds would propel Marcy, Butler and their research team into the media spotlight, and forever change our view of the cosmos.
'A spine-tingling experience'
But for the moment, on that solemn drive down the mountainside, Marcy and Butler were alone with their world-altering news. "We knew we were the only people on the planet to be sure that 51 Peg, the planet, really did exist," Marcy said recently. "It was exhilarating. We were absolutely thrilled to know an historic moment in science history was happening before our eyes. It was a truly spine-tingling experience."
Still, the astronomical pioneers had a few struggles ahead to gain the acceptance of the scientific community. The hunt for extrasolar planets -- exoplanets, for short -- had a poor track record, with decades' worth of false detections. Among them was the thrilling discovery of a planet orbiting Barnard's star in the 1960s; it turned out to be an unnoticed shift of a telescope lens. Once the shift was accounted for, the "planet" disappeared.
The early '90s had seen the actual detection of "pulsar planets," but these seemed too strange to count, orbiting a rapidly spinning, radiation-spewing stellar remnant called a pulsar. Most scientists would reserve the "first" designation for a planet orbiting a normal star.
"The whole field had a snake-oil sort of feel to it," Butler said in a recent interview. "For the previous fifty years or so, there were many announcements, all proved to be wrong. If we went to a meeting and said we were looking for extrasolar planets, we might as well have said we were looking for little green men."
Even Marcy greeted the announcement of 51 Peg, made at a scientific conference in Florence, Italy, by Mayor and Queloz, with a bit of a yawn -- at first.
"This claim on October 6, 1995, of the first planet ever discovered was sort of business as usual," he said. "Here's another false claim. This one is more obviously a false claim. The orbital period is claimed to be 4.3 days. Nobody in their right mind thought planets could orbit so close to a star."
But the four nights of observations at the Lick Observatory -- perfectly coinciding with 51 Peg's four-day orbit -- changed all that. Both the Mayor and Marcy teams had been trying to develop a planet-hunting technique based on wobbling stars. The wobbles, known as the star's "radial velocity," were induced by the gravitational tugs of orbiting planets. The starlight wavelength was compressed, then stretched, as the star moved toward and away from astronomers' telescopes.
Now, Mayor and Queloz had proven that the technique worked. And a few days later, Marcy and Butler validated both the method used by Mayor's team and their own very similar detection method.
But Marcy and his team realized something more. The only thing that had kept them from beating Mayor's group to that first detection was a perfectly reasonable assumption: that big planets moved in stately orbits, like the 12 years it took Jupiter to take one lap around the sun.
Either they would have to watch stars for a very long time, or they would have to refine their wobble detector until it could pick up the very tiny shifts in a star's position caused by small planets in tighter, faster orbits.
They were working on just this type of refinement when Mayor announced his discovery. More importantly, they had been recording observations with their wobble-detecting device, known as a spectrograph. Sure enough, when they took another look, big, star-hugging planets began popping out of their data.
At a meeting of the American Astronomical Society in January 1996, Marcy announced two more planet discoveries: 70 Virginis and 47 Ursae Majoris. The first had a 116-day orbit -- far more reasonable than 51 Peg's scorching four days -- and its orbit was elliptical, making it unlikely to be anything but a planet. The orbit of 47 Ursae Majoris was more reasonable still: 2.5 years. Together, they provided a "bridge" to our own solar system, Marcy said, with planets behaving themselves as proper planets should.
The discoveries vaulted Marcy and his team into scientific celebrity status, with appearances on nationwide nightly news shows; their new planets even made the cover of Time magazine.
And the Marcy-Butler team was just warming up. The floodgates were opened. They discovered at least 70 of the first 100 exoplanets that were found in the years that followed. Their pioneering, planet-hunting safari went on for a decade. Soon, however, the landscape would change yet again.
The gold rush of planet finding kicked into high gear with the launch of the Kepler Space Telescope in 2009. This spacecraft nestled into an Earth-trailing orbit, then fixed its eye on a small patch of sky -- and kept it there for four years.
Within that patch were more than 150,000 stars, a kind of cross-section of an arm of our own Milky Way galaxy, as if Kepler were shining a searchlight into deep space. Kepler was looking for planetary transits -- the infinitesimally tiny dip in starlight that occurs when a planet crosses the face of the star it is orbiting.
The method only works for distant solar systems whose planets' orbits, from our perspective, are seen edge-on. This way, an exoplanet is silhouetted as it passes between Kepler and its host star, reducing the starlight measured by Kepler.
The fifth time's the charm
Kepler was the brainchild of William Borucki of the NASA Ames Research Center in Moffet Field, California. Borucki, who retired in early July 2015, doggedly pressed his case for Kepler. During the '90s, his proposed designs were rejected no less than four times. He finally won approval from NASA in 2001.
But no one knew what Kepler might find, or even if it would find anything at all.
"We launched Kepler, to some extent, like Magellan or Columbus went to sea, not knowing quite what we were going to encounter," said James Fanson, deputy manager in the Instruments Division at NASA's Jet Propulsion Laboratory in Pasadena, California. Fanson was Kepler's project manager when the spacecraft was launched.
"We knew we were going to make history," he said. "We just didn't know what history we were going to make."
Kepler's transit watch paid off, however, identifying more than 4,600 candidate planets hundreds to thousands of light-years distant. So far, 1,028 of those have been confirmed -- some of them Earth-sized planets that orbit within their star's so-called habitable zone, where liquid water can exist on a planet. Scientists are still mining Kepler data, regularly turning up new planetary candidates and confirming earlier finds.
Kepler itself ended its initial mission in 2013, when two of four reaction wheels used to keep the spacecraft in a stable position failed. But the Kepler science team developed clever ways to continue squeezing useful data out of the space telescope, relying on the subtle pressure of sunlight to stabilize it on one axis. Kepler is now in its second phase of life, and it's still discovering planets.
Preceding Kepler was the groundbreaking COROT satellite, a European venture launched in 2006 that discovered numerous planets before it ceased functioning in 2012 -- including the first rocky planet found to orbit a sun-like star. COROT used the transit method to detect exoplanets, and was the first space mission dedicated to that purpose.
The prolific discoveries still flowing from the Hubble Space Telescope include not only exoplanets, but characterizations of exoplanet atmospheres, identifying a variety of gases. And the Spitzer Space Telescope has found water vapor in exoplanetary atmospheres as well as weather patterns.
Both the wobble and transit methods, relied upon by the exoplanet pioneers, are still in use today, along with several other techniques. And 20 years after the first discovery, the exoplanet total is up to more than 5,000 candidates, with more than 1,800 of those confirmed.
A new reality
The galaxy, it seems, is crowded with planets. Yet we are not yet able to answer the big question: Are we alone?
A new generation of telescopes in the years and decades ahead, on the ground and in space, will continue to search for an answer. One critical tool will be the same one pioneered by Marcy and the other early planet hunters: spectroscopy. They used this method to dissect the light coming from distant stars, revealing their back-and-forth, planet-induced wobbling as the starlight was stretched and compressed; the newest generation of instruments will do the same thing to the light from the atmospheres of exoplanets. Splitting this planetary light into its constituent parts, a little like the rainbow colors of sunlight shining through a prism, should reveal which gases and chemicals are present in those alien skies.
And one day, some of those atmospheric constituents might suggest the presence of life far beyond planet Earth.
For more information about exoplanets and NASA's planet-finding program, visit:
News Media ContactFelicia Chou
NASA Headquarters, Washington
Jet Propulsion Laboratory, Pasadena, Calif.
Written by Pat Brennan, NASA-JPL | 0.914855 | 3.644529 |
If you take humanity's current energy and technological capacity and project a steady increase into the future, the chances of us reaching the stars any time soon look bleak. Even our nearest stellar neighbor is at least 300 years away.
Of course, humans could technically reach Alpha Centauri long before the 2300s. The Voyager probes, for instance, are headed into interstellar space, and it wouldn't be that difficult to take another probe and aim it in the rough direction of Alpha Centauri. But that probe would still take a long time to get there, its instruments would probably give out long before it arrived at the star, and what data it could provide would be hugely limited.
On the other hand, an Alpha Centauri probe that could reach the star within a human lifetime (say, 75 years), could actually assume an orbit around the star to maximize the data it could collect (which would be considerably more complicated than a simple flyby), and possessed sufficient communications ability to relay its data back to Earth would probably have to weigh at least 10,000 kilograms. That's about 13 times the mass of the Voyager probes and 20 times the mass of the New Horizons probe currently headed out to Pluto.
And that's the big problem. It would take a lot of energy to build and launch such a probe, and it's questionable how much scientists could actually consume in the building of the probe. According to new calculations by astronomer Marc Millis, the maximum percentage of its total energy the US devoted to spaceflight in any given year was only about a millionth of its total supply. That's not a lot of energy to play around with when launching such a sophisticated interstellar probe.
In fact, based on his estimates for the world's energy growth, the earliest possible launch for an Alpha Centauri probe is 2247, with the average launch date around 2463. And even that presumes some breakthrough in spacecraft propulsion. If we're stuck with what we're using now, then we couldn't launch the probe until 2301, with the more likely date some time around 2566.
Obviously, these are only rough estimates, which Millis himself readily admits. But they're worth considering in terms of how much energy it will take to get to another star system, even it's just a reasonably robust probe. For more on these numbers, check out our friend Paul Gilster's analysis over at Centauri Dreams. | 0.858047 | 3.611192 |
Students build star-tracking instrument for NASA
Experiment tests new detector technology operable at cryogenic temperatures
Rochester Institute of Technology undergraduates are making a “compass” for rockets using a new kind of detector technology. The instrument will fly on a NASA technology demonstration mission later this year.
The student team is designing, building—and deploying—a telescope and camera that will orient the rocket payload based on the images of stars. RIT’s Cryogenic Star Tracking Attitude Regulation System is funded by a $200,000 grant from NASA’s Undergraduate Student Instrument Project Flight Research Opportunity program. The NASA program is designed to give undergraduates experience developing and flying experiments relevant to NASA’s mission.
RIT professor Michael Zemcov proposed the experiment to test detectors made of metal-oxide semiconductor, or CMOS, a promising new material that can operate at liquid nitrogen temperatures, minus 320 degrees Fahrenheit. These cryogenic temperatures can significantly reduce dark current in the sensor and increase instrument sensitivity. In contrast, the standard technology used in astronomical imaging and in consumer electronics—charge-coupled detectors, or CCDs—is inoperable at cold temperatures.
RIT’s prototype represents a step toward a fully cryogenic optical detector that someday could improve the sensitivity of NASA’s deep-space cameras, said Zemcov, assistant professor of physics at RIT. The star tracker will fly in a technology demonstration payload on a suborbital sounding rocket that will launch in December from NASA’s Wallops Flight Facility on Wallops Island, Va., with experiments from other universities and NASA laboratories. Sounding rockets are cousins of military ordnance, like surface-to-air missiles, which fly to an altitude of approximately 200 miles, and represent an affordable way to conduct science experiments in space.
Following a successful initial flight, a second RIT-built instrument will fly on a NASA rocket experiment to measure the light from faint and distant galaxies. The Cosmic Infrared Background ExpeRiment 2, or CIBER-2, is led by the California Institute of Technology. Zemcov is a member of RIT’s Center for Detectors and the Future Photon Initiative and a co-investigator on CIBER-2.
“We needed to build a star tracker for this science payload,” Zemcov said. “The problem is that most of the detectors we have don’t work at the cold temperatures we require.”
The RIT student team brings the specialty of several disciplines to the project. Everyone has a job: Kevin Kruse, a fifth-year BS/MS electrical engineering major from Port Jefferson Station, N.Y., is the electrical engineer and team leader; Chris Pape, a third-year student in the BS/MS program in mechanical engineering technology/mechanical and manufacturing systems integration from Douglassville, Pa., is the mechanical engineer; Benjamin Bonder, a fifth-year BS/MS electrical engineering major from Geneva, N.Y., is the computer engineer; Poppy Immel, a fifth-year BS/MS dual-degree major in computational mathematics and computer science from Castleton, Vt., is the computer scientist; Matthew Delfavero, a third-year physics major from Annapolis, Md., is the physicist; and Hyun Won, a fourth-year international business student born in South Korea and who grew up in Ann Arbor, Mich., is the project manager. Most of the students are using the project as co-op experience.
“The aim is to control this sensor and make it work at cold temperatures,” Kruse said. “Then we’ll launch it into space to take pictures. A future mission would involve us guiding the rocket using the images we take.”
The team’s mentors are Zemcov; Dorian Patru, professor of electrical engineering; and Chi Nguyen, a Ph.D. student from Vietnam in the astrophysical sciences and technology graduate program.
“CSTARS will verify a new instrument design, so I’m interested in seeing how well the implemented instrument can meet our expectations,” Nguyen said. “As a graduate student, this project is an excellent opportunity for me to gain mentoring experience and experience working with NASA.” | 0.859069 | 3.012229 |
Asteroid 2007 AG passed by the Earth at a distance of about 8 747 000 km (22.7 times the average distance between the Earth and the Moon, or 5.85% of the distance between the Earth and the Sun), slightly before 11.45 pm GMT on Tuesday 26 December 2017. There was no danger of the asteroid hitting us, though were it to do so it would have presented a significant threat. 2007 AG has an estimated equivalent diameter of 180-570 m (i.e. it is estimated that a spherical object with the same volume would be 180-570 m in diameter), and an object of this size would be predicted to be capable of passing through the Earth's atmosphere relatively intact, impacting the ground directly with an explosion that would be 1 175 000 to 8 825 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater 2.5-8.0 km in diameter and devastation on a global scale, as well as climatic effects that would last decades or even centuries.
The calculated orbit of 2007 AG. Minor Planet Center.
2007 AG was discovered on 8 January 2007 by the University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount Lemmon in the Catalina Mountains north of Tucson. The designation 2007 AG implies that the asteroid was the seventh object (object G) discovered in the first half of January 2007 (period 2007 G).
2007 AG has a 223 day orbital period, with an elliptical orbit tilted at an angle of 11.9° to the plain of the Solar System which takes in to 0.45 AU from the Sun (45% of the distance at which the Earth orbits the Sun; slightly outside the orbit of the planet Mercury) and out to 0.99 AU (99% of the distance at which the Earth orbits the Sun). This means that close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in January 2015 and the next predicted in December 2020. Although it does cross the Earth's orbit and is briefly further from the Sun on each cycle, 2007 AG spends most of its time closer to the Sun than we are, and is therefore classified as an Aten Group Asteroid. As an asteroid probably larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, 2007 AG4 is also classified as a Potentially Hazardous Asteroid.
2007 AG also has frequent close encounters with the planets Mercury, which it is thought to have last passed in February this year, and is next predicted to pass in January 2025, and Venus, which it is next predicted to pass in June 2059. Asteroids which make close passes to multiple planets are considered to be in unstable orbits, and are often eventually knocked out of these orbits by these encounters, either being knocked onto a new, more stable orbit, dropped into the Sun, knocked out of the Solar System or occasionally colliding with a planet.
Follow Sciency Thoughts on Facebook. | 0.839013 | 3.764243 |
Scientists recently reported new details about the second interstellar object ever seen passing through our solar system.It is a comet called 2I/Borisov.
Comets are made up of frozen gases, rock and dust that orbit stars.The Reuters news agency likens them to dirty snowballs.Comets leave behind a mix of gas and dust in space as they move.
2I/Borisov is different from other comets, scientists have observed.Researchers reported on Monday that gas coming off 2I/Borisov had high levels of carbon monoxide -
far more than comets formed in our solar system.
Carbon monoxide is poisonous to human beings.It forms as ice only in the coldest places.The presence of so much carbon monoxide, the researchers said,suggests 2I/Borisov was formed differently than comets from our solar system.It could have formed in a very cold part of its home star system or around a star cooler than the sun.
Dennis Bodewits is a planetary scientist at Auburn University in the United States.He was the lead author of one of two 2I/Borisov studies.Both appear in the publication Nature Astronomy.
"We like to refer to 2I/Borisov as a snowman from a dark and cold place," Bodewits said.He noted that, "comets are left-over building blocks from the time of planet formation.For the first time,we have been able to measure the chemical composition of such a building block from another planetary system while it flew through our own solar system."
Amateur astronomer Gennady Borisov was the first person to identify the comet in August of 2019.The comet is thought to be about 1 kilometer wide.It has flown through interstellar space after being forced out from its original star system.
Bodewits said the comet was born long ago in a mix of gas and dust circling around a newly formed star.He said it came from a place that must have been rich in carbon monoxide.
That star may have been what is called an M-dwarf, far smaller and cooler than our sun.M-dwarf stars are the smallest kind of star known to scientists, Bodewits said.
At first, researchers believed that 2I/Borisov was like comets made in our solar system.However, information gathered by the Hubble Space Telescope and an observatory in Chile showed differences.
The researchers also found a large amount of hydrogen cyanide at levels similar to comets from our solar system.
Martin Cordiner was the lead author of the second study.He said, "This shows that 2I/Borisov is not a completely alien object,and confirms some similarity with our ‘normal’ comets,so the processes that shaped it are comparable to the way our own comets formed."
Cordiner is an astrobiologist working for NASA, the U.S. space agency.He is with the Goddard Space Flight Center in Maryland.
The only other interstellar visitor discovered in our solar system was a rocky object called ‘Oumuamua’.It was found in 2017.
Im John Russell. | 0.914059 | 3.516399 |
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