December 24, 2012
Cosmic Light Show Expected For Christmas
[ Watch the Video: ScienceCasts: Christmas Sky Show ]
April Flowers for redOrbit.com - Your Universe OnlineWhat Christmas celebration could be complete without beautiful lights? This Christmas, the light show will not just be in your neighbor's yard, but in the sky as well.
On the evening of December 25, Jupiter and the Moon are having a Christmas conjunction, which will be visible around the globe. Normally cut off from astronomical displays because of light pollution, even city dwellers will be able to see the bright pair of celestial bodies. They will be separated by only 2 degrees, creating a beautiful apparition.
Jupiter and the Moon are already two of the most satisfying objects for the amateur astronomer, and those of you receiving a telescope for Christmas will not be disappointed. Jupiter's storms and cloud belt will be visible, along with the Moon's mountains and impact craters. The four Galilean satellites circling Jupiter's giant body like a miniature solar system will also be visible.
Great Red Spot On Display
Another amazing feature that warrants a look is Jupiter's Great Red Spot, which will be on display as well. The enormous swirling storm — easily twice as wide as the planet Earth — is "spinning up" according to astronomers.
Glenn Orton of NASA's JPL reports that "the Red Spot is shrinking," equating it to "the iconic picture of a figure skater pulling her arms in to spin faster. As the size contracts, the spin rate increases."
Head of the British Astronomical Association's Jupiter Section, John Rogers noticed the phenomenon in recent pictures of Jupiter taken by amateur astronomers. The pictures allowed Rogers to track a dark cloudy feature as it swirled three times around the Red Spot's central vortex, completing the circuit in only 4.0 days. This is shorter than the 4.5 days Rogers measured in 2006 using the same method.
Rogers said in a recent NASA statement, "The trend of decreasing rotation period has been consistent at least since Voyager visited Jupiter in 1979." He explains as the spot shrinks, it also changes shape. It is currently circular, where decades ago it was more sausage shaped.
"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."
For viewers across North America, Jupiter's Red Spot will be transiting the planet's middle, perfectly positioned for telescopic observations on Christmas. You don't need a telescope, though, just step outside at sunset and look east.
This phenomenon begs the question, is this the basis for the Christmas Star legend?
According to David Reneke, of Australia's Sky and Space Magazine, it is not...exactly. Reneke believes astronomers might have finally found the answer to one of the most enigmatic questions of all time; was the Christmas star real?
Using the gospel of Mathew — seemingly the oldest of the gospels — and modern astronomy software programs, Reneke has turned back the hands of time to reproduce the night sky exactly as it was thousands of years ago.
“We found out something startling.” said Reneke, “It looks like the ℠Christmas star´ really did exist,”
Reneke claims most biblical scholars agree Christ was born between 3BC and 1AD. Armed with this approximate date, Reneke went searching through historical records and computer simulations. He made the assumption the "Star of Bethlehem" would not be only a local phenomenon, but would also be visible to sky-watchers in other parts of the world. What he found was a series of planetary groupings, known as conjunctions, during the years 3BC and 2BC.
“Like the final pieces of a difficult jig-saw puzzle, our fabled biblical beacon is starting to reveal itself,” David said. “On 12 August, 3 BC, Jupiter and Venus appeared very close together just before sunrise, appearing as bright morning ℠stars.´ It would have been visible in the eastern dawn sky of the Middle East from about 3:45 to 5:20 a.m.”
The heavens weren't finished showing off yet, though. Ten months later, on June 17, 2BC, Venus and Jupiter were again in conjunction, this time in the constellation Leo. The planets were so close this time, to the ancient astronomer, they would have appeared as a single, bright object in the sky.
Reneke admits there might be other explanations for the Christmas star, including that it is only mythological. He says, however, it makes the search more rewarding to find such an astronomical event in the more likely time for the Nativity.