Jimmy Westlake: Look out for Geminid meteor shower
Shower appears to be getting stronger, better each year
December 12, 2011
Steamboat Springs — The annual Geminid meteor shower peaks this week, but it will be competing against the bright December moonlight. Unlike most other annual meteor showers that have been around 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. Astronomers predict that this year's Geminid meteor shower could produce 120 meteors per hour at its peak.
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 3 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 some Geminid meteors several days before the shower actually peaks Tuesday night and into Wednesday morning, and for several days thereafter. 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 over the sky. Gemini rises above our eastern mountains well before midnight, so the action could start earlier than in most meteor showers. Geminid meteors tend to be slower than the August Perseids or the November Leonids, producing long, graceful streaks across the sky. This year, the waning gibbous moon will rise at about 8 p.m. Tuesday and likely will drown out many of the fainter meteors, but there will be plenty of bright ones to keep you awake. Remember, the closer to dawn on Wednesday that you look, the more meteors you are likely to see, until daylight begins to brighten the sky. Keep the moon to your back or behind a building to preserve your night vision. Next December, the moon will be new on the night of the Geminid meteor shower's peak, leaving the sky totally dark for the best meteor shower of the year.
Jimmy 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 across the world. Check out Westlake's astrophotography website at http://www.jwestlake.com.