Jimmy Westlake: Here come the Geminid meteors
December 8, 2009
The Gemini constellation is about to become a hot spot of activity during December. Sky-watchers will notice lots of fiery streaks of light coming from Gemini as a result of the annual Geminid meteor shower. The slender waning crescent moon won't rise until nearly 6 a.m. Dec. 14, the morning 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 we observe seems to be an asteroid rather than a comet. In 1984, astronomers discovered a small object, about 3 miles across, orbiting along the same path as the dust swarm that generates our Geminid meteor shower. Now named Phaethon, the asteroid might well 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 could be a leftover from its comet days.
You can begin to see a few Geminid meteors about a week before the shower peaks on the night of Dec. 13, when a single observer might 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 they will be visible all across the sky. Gemini rises above the eastern mountains well before midnight, so the action could start earlier than in most meteor showers. And Geminid meteors tend to be slower than the August Perseids or November Leonids, producing long, graceful streaks across 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 Geminid shower has appeared on schedule and seems to be getting stronger and better each year.
Astronomers predict that this year's Geminid meteor shower might be the best ever, reaching 140 meteors per hour at the peak. Now that's worth staying up late to see!
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 could be the best meteor
Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. He is an avid astronomer whose photographs and articles have been published all around the world. Check out Jimmy's Web site at http://www.jwestlake.com.