Christmas Sky Show   
       
   Dec. 21, 2012:  Just when you thought Christmas was over: At the end of the   
   day on Dec. 25th, a pair of holiday lights will pop out of the deepening   
   twilight. Jupiter and the Moon are having a Christmas conjunction.   
       
   It's a beautiful apparition, visible all around the globe. Even city dwellers,   
   who often miss astronomical events because of light pollution, can see the   
   show. Separated by less than 2 degrees, the bright pair will beam right   
   through urban lights.   
       
   http://www.youtube.com/watch?v=NzSUo-4ctcU   
       
   A new ScienceCast video previews the Christmas-night conjunction of the Moon   
   and Jupiter. Play it   
       
   For anyone who gets a telescope for Christmas, the timing is perfect. Jupiter   
   and the Moon are among the most satisfying targets for backyard optics. A   
   quick sweep of the telescope from Jupiter to the Moon and back again will   
   reveal Jupiter's storms and cloud belts, the Moon's mountains and impact   
   craters, and of course the four Galilean satellites circling the giant planet   
   like a miniature solar system.   
       
   Jupiter's trademark Great Red Spot will also be on display--and it is worth a   
   look. Astronomers recently announced that the enormous swirling storm, twice   
   as wide as the planet Earth, is "spinning up."   
       
   Actually, explains planetary scientist Glenn Orton of NASA's Jet Propulsion   
   Laboratory, "the Red Spot is shrinking." He likens it to "the iconic picture   
   of a figure skater pulling her arms in to spin faster. As the size contracts,   
   the spin rate increases."   
       
   John Rogers, head of the British Astronomical Association's Jupiter Section,   
   noticed the phenomenon in recent pictures of Jupiter snapped by amateur   
   astronomers. He was able to track a dark cloudy feature as it swirled three   
   times around the Red Spot's central vortex. The circulating streak completed   
   the circuit in only 4.0 days, shorter than the 4.5 days Rogers measured in   
   2006 using the same method.   
       
   http://www.youtube.com/watch?v=NzSUo-4ctcU   
       
   Jupiter's Great Red Spot is spinning up. Learn more about it in the   
   ScienceCast video Christmas Sky ShowLooking back in time, "the trend of   
   decreasing rotation period has been consistent at least since Voyager visited   
   Jupiter in 1979," says Rogers. As the spot shrinks, it also changes shape.   
   Decades ago the Red Spot looked like a sausage - now it's more circular.   
       
   What happens next is hard to say. "Perhaps the Red Spot will continue to   
   shrink and eventually disappear," speculates Rogers. "Or perhaps it will be   
   rejuvenated if some new storm arises to reinforce it."   
       
   One thing is certain, Christmas night is a good time to look. The Red Spot   
   will be transiting Jupiter's middle for observers across North America and   
   will be perfectly positioned for telescopic observations.   
       
   But you don't need a telescope to enjoy the show. Step outside at sunset on   
   Dec. 25th and look east. After all, Christmas isn't really over until you've   
   seen the holiday lights.   
       
       
   Author: Dr. Tony Phillips |Production editor: Dr. Tony Phillips | Credit:   
   Science@NASA   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.82   
    * Origin: NCS BBS Houma, LoUiSiAna (1:3828/7)