SJAA Ephemeris December 2011 | SJAA Home | Contents | Previous | Next

The Last Month in Astronomy


NOV-10-2011 • Curiosity Ready • The Mars Science Laboratory, aka ‘Curiosity”, is set to launch on November 25. Its launch window ends on December 18. If all goes well the rover will land near Gale Crater next August. That landing will use a new method involving a Sky Crane to lower the 1 ton rover to the Martian surface.

NOV-10-2011 • First stars not so big • Astronomers used to think that the earliest stars were behemoths, more than 100 solar masses. Recent simulations suggest the stars were smaller perhaps less than 50 solar masses. According to Takashi Hosokawa (JPL) the lead author of the study published in the Nov.11 issue of Science, “The first stars were definitely massive, but not to the extreme we thought before. Our simulations reveal that the growth of these stars is stunted earlier than expected, resulting in smaller final sizes.”

NOV-07-2011 • 2005 YU55 • The near-Earth asteroid 2005 YU55 came closer to the Earth than the size of the lunar orbit. This was the closest that this asteroid has been for the last 200 years. NASA used the radio telescope at Goldstone to produce a movie of the pass.

NOV-05-2011 • Voyager 2 using Backup • Imagine that you have some data backup tape that was created in 1977. And imagine that you are going to use it for the first time in November of 2011. That’s not quite a good analogy for Voyager 2 turning on the backup roll control thrusters but it will have to do. After using the roll control thrusters 318,000 times over 34 years the spacecraft has been ordered to switch to the backup. Doing so will save about 12 watts of power. The Voyager 2 power supply is now providing 270 watts.

NOV-02-2011 • Mars Always Dry • A new report printed in Nature says that Mars was probably never wet enough or warm enough to support life. True, there might have times when liquid water could be seen on the surface but it was for a very short period only. Lead author Bethany Ahlmann (Caltech/JPL) said “The most stable Mars habitats over long durations appear to have been in the subsurface.” So search for life on Mars, even ancient life, will probably require digging implements of some kind. Upcoming missions to Mars include the launch of Curiosity set for late November and Maven with a possible launch in 2013.

NOV-01-2011 • Inverse femtobarn • An inverse femtobarn is a measurement of particle collision events. It comes out to a number of particle collisions that has a magnitude of 10^13. The LHC completed a half-year run on October 30, 2011. The total data captured was almost 6 inverse femtobarns. The Higgs particle has quite been nailed down yet but according to a spokesperson “... we have constrained the Higgs particle to the light end of the possible mass range ... this is where both theory and experimental data expected it would be ...”

NOV-01-2011 • Mercurial geysers • The MESSENGER spacecraft has found structures on the surface of Mercury that may be geysers of hydrogen. Some of Mercury’s crater have features that have a very high albedo (reflectiveness). The hydrogen may have been captured during Mercury’s formation. The hydrogen gets released and reacts with iron sulphide which is known to exist on Mercury. The result would be a light dusting of iron and that would be very bright features that are seen.

OCT-25-2011 • Goodbye Elenin • The comet Elenin is gone. This comet was first detected by Russian astronomer Leonid Elenin. It was also given a formal astronomical name, C/2010 X1. Predictably, a number of people took this opportunity to predict all manner of disasters. But the damage was actually done to the comet. As it passed the sun, Elenin disintegrated leaving a faint dust cloud to mark its former grandeur.

OCT-20-2011 • Watery planetary disk • The Herschel spacecraft has detected a watery disk around a young star. TW Hydrae is an orange dwarf star, smaller and cooler than the sun. It is surrounded by a disk with a radius of 200 AU. Lead author Michiel Hogerheijde (Leiden Observatory) said “Our observations of this cold vapor indicate enough water exists in the disk to fill thousands of Earth oceans.” Previously, scientists found warm water vapor near the central stars of planetary disks. This new study shows that there is a reservoir of water equivalent to thousands of Earth oceans. This water is in the form of ice solids. Water in the form of water vapor is only seen near the star. TW Hydrae is 0.6 solar masses that is 10 million years old. It belongs to a class of young stars called T Tauri stars. It is about 175 light years from the sun. This study further suggests that comets do not form at the further out sections of the solar nebula but instead contain mixtures of ice from all parts of the planet forming disk.


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