Jimmy Westlake: Here come the Geminids
December 11, 2012
Unlike most other annual meteor showers that have been observed for centuries, the Geminid shower is a relative newcomer to our skies. No one reported seeing any Geminid meteors before the year 1862, but every December since that year, the Geminid shower has appeared on schedule and seems to be getting stronger and better each year.
The Geminid meteors also are unique because their parent body seems to be a rocky asteroid rather than an icy comet. In 1984, astronomers discovered a small object, about three miles across, orbiting along the same path as the dust swarm that generates our Geminid meteor shower. Now named Phaethon, this 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 see a few Geminid meteors several days before and after the shower actually peaks in the predawn hours of Thursday and Friday. A single observer might see dozens of "shooting stars" or meteors each hour near the peak. The meteors will 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.
Geminid meteors tend to be slower than the August Perseids or November Leonids, producing long, graceful streaks across the sky. This year, the moon is new on Thursday, leaving the sky nice and dark for meteor watching. Gemini is highest in our sky at about 2 a.m., so you'll see the most meteors around that time.
So, bundle up against the cold, break out the hot cocoa, and enjoy the best meteor shower of 2012.
Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. Check out Westlake's astrophotography website at http://www.jwestlake.com.