Jimmy Westlake's Celestial News column appears monthly in the Steamboat Today.
Find more columns by Westlake here.
Steamboat Springs The constellation of Gemini the Twins will be a hot spot of activity during December. Not only will Mars be glowing like a red-hot ember near the feet of the Twins as it passes closest to Earth on Dec. 19, but sky-watchers also will notice lots of fiery streaks of light coming from Gemini as a result of the annual Geminid meteor shower. The slender waxing crescent moon will set early Dec. 13, the night of the peak of the meteor shower, leaving the sky nice and dark for meteor-watching.
The Geminid meteors are unique because the parent body for the meteors seems to be an asteroid rather than a comet. In 1984, astronomers discovered a small asteroid, about three miles across, orbiting along the same path as the dust swarm that generates our Geminid meteor shower. Now named Phaethon, the asteroid might actually be a burned-out comet in disguise - that is, a comet that has lost all of its ice after many passes around the sun and is now just the rocky skeleton of a once-active comet. The trail of dust particles that follows Phaethon around the sun is a leftover from its comet days.
You can begin to see a few Geminid meteors about a week before the shower peaks at midday Dec. 14, but on the night before the peak (that's Thursday, Dec. 13 into the morning of Friday, Dec. 14), a single observer could see dozens of "falling stars" or meteors each hour. The meteors will seem to fan out from a point near the twin stars Castor and Pollux in the constellation Gemini, but you will see them all over the sky.
Unlike the Perseid meteor shower that has occurred every August for centuries, the Geminid meteor shower is a relative newcomer. No one reported seeing any Geminid meteors before the year 1862, during the Civil War, but every December since that year, the Geminids have appeared on schedule and seem to be getting better and better.
If the sky is clear on the night of Dec. 13, bundle up against the cold, stretch out on the ground or a comfortable recliner, and watch the fireworks. Remember, the closer to dawn on Dec. 14 you look, the more meteors you will likely see until daylight begins to brighten the sky. You won't want to miss what is arguably the best meteor shower of 2007!
Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. He is an avid astronomer whose photographs and articles have been published on the Web sites of CNN.com, NASA's "Astronomy Picture of the Day" website, Spaceweather.com, Space.com, Discover.com, MSNBC.com, NationalGeographic.com, and in Sky & Telescope, Astronomy, Night Sky, Discover, and WeatherWise magazines.