Bakersfield College

December 3, 2011

Bakersfield Night Sky – December 3, 2011
By Nick Strobel

The Mars Science Laboratory (MSL) is now on its way to Mars and will land in Gale Crater on August 6, 2012. The rover, named Curiosity, will be the most advanced and largest rover to explore Mars with a suite of science experiments about 15 times as massive as those on the Mars Exploration Rovers, Spirit and Opportunity, that landed in January 2004. While not being able to detect biological activity, MSL will be able to tell if the site is habitable (for microbes, that is), to detect organic compounds, and to assess what the environment was like in the past. Unlike the solar-powered Spirit and Opportunity, MSL will use a radioisotope power system like that used in other deep space missions such as Voyager and Cassini (all still communicating with the Earth!). Though the mission is only supposed to be two years long, it is hoped that MSL will have the same sort of longevity as its smaller predecessors. Opportunity is still functioning and is exploring a large crater called Endeavour. Go to http://mars.jpl.nasa.gov to follow the Martian explorers on the ground and in orbit.

Dawn has finished its high-altitude mapping orbit around the asteroid Vesta about 410 miles above Vesta's surface. As it spirals down to its closest orbit only 110 miles above the surface, it continues taking high-resolution images, detecting things as small as 45 meters across, and analyzing rock types with its optical and infrared spectrometer. In its high-altitude mapping orbit, Dawn took 12 hours to orbit Vesta, but in the lowest orbit Dawn will take only 4 hours to orbit Vesta. The closest orbit phase of the mission will focus on mapping Vesta's gravity field to determine its interior structure and use of the gamma-ray and neutron detector to probe the types of atoms to a depth of one meter or so. After exploring Vesta, Dawn will spiral outward and head toward Ceres for a rendezvous with the largest asteroid (and dwarf planet) in February 2015. Go to http://dawn.jpl.nasa.gov for more about Dawn's discoveries.

Cassini, still going strong after its arrival at Saturn in 2004, is currently studying a huge storm that erupted a year ago and has been raging ever since. It covers an area about eight times the surface area of the Earth and is about 500 times bigger than the previous "big storm" in 2009. Unlike Jupiter and Earth where storms happen all the time, Saturn is usually pretty calm for several years at at ime and then it will erupt with a large storm lasting months before settling down again. Earlier last month Cassini flew by Enceladus, the moon that has geysers indicating a sub-surface layer of liquid water. The geysers eject watery material with enough energy to escape Enceladus and create Saturn's E-ring. This particular fly-by of Enceladus was the first time that Cassini used its radar to map part of Enceladus. Up to then the radar had been used exclusively for mapping Saturn's largest moon, Titan. Titan has a thick atmosphere of nitrogen, methane, and other hydrocarbons that make a thick smog. The results from the Enceladus radar observations will enable a comparison of the radar properties of a moon with known composition (Enceladus) with that of Titan. It will also enable us to understand the structure and composition of the material just below the surface. Analysis continues! Go to http://saturn.jpl.nasa.gov for more about Cassini's exploration of the ringed planet and its moons.

Closer to home a significant astronomical event happens next Saturday in the pre-dawn hours of December 10th. The Full Moon will pass through the Earth's umbra, the region of total shadow, to make a total lunar eclipse. The first chart below shows the details of the lunar eclipse as seen from Bakersfield. At 4:45 AM, the Moon will enter the umbra and over the next hour and twenty minutes, the Earth's shadow will engulf the Moon. The moon will be a quarter of the way up in the western sky between the horns of Taurus. From 6:05 to 6:57 AM the Moon will travel through the umbra and for us that's all we'll get to see of the end of the eclipse since the Moon will set at 6:57 AM (though the mountains and air particulates close to the horizon will probably cut off our view sooner than that). Those further west of us in the Pacific Ocean (e.g., Hawaii) will be able to experience more of the eclipse. A few nights later on December 13th and 14th you may be able to see some of the meteors of the Geminid meteor shower but the Waning Gibbous Moon is going to make it difficult to see any but the brightest of them.

This evening Venus will blaze away low in the southwest after sunset. It continues climb up away from the Sun (see the inset of the second chart below). On the other side of the sky, Jupiter will be a third of the way up in the southeastern sky on the east (left) side of Pisces and the Waxing Gibbous Moon will be on the west (right) side of Pisces (see the second chart below). The waxing Moon will pass by Jupiter on December 6th and then pass under the star cluster, the Pleiades, in Taurus on December 8th. All of the stars of Orion will be high enough to see by about 7:45 PM tonight and the brightest star of the night sky, Sirius, in Canis Major will be visible shortly after 9 PM (see the third chart below). Mars below the middle of Leo rises around midnight and Saturn on the east (left) side of Virgo is now visible in the pre-dawn hours rising at around 3:30 AM. The bright star of Virgo, Spica, will be to the right of Saturn (see the fourth chart below).

Want to see more of the stars at night and save energy? Shield your lights so that the light only goes down toward the ground. See www.darksky.org for how.
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Nick Strobel
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com

Kern Community College District