Jimmy Westlake's Celestial News column appears Tuesdays in the Steamboat Today.
Find more columns by Westlake here.
Steamboat Springs With the recent Perseid meteor shower still fresh on their minds, sky-watchers are now turning their attention to a possible meteor storm on Sept. 1 called the Alpha Aurigids. This is typically a ho-hum annual meteor shower that produces a paltry six meteors per hour at its peak, but at least three times in the past century, the Alpha Aurigids have roared to life with an unexpected burst of activity. In the years 1935, 1986 and 1994, several observers noted dozens of bright, oddly colored meteors coming from the direction of the constellation Auriga, the Charioteer, near the bright star Capella. The spectacular displays were very brief, only lasting for about 50 minutes to an hour, and few people witnessed them because they were unexpected.
The source of these Aurigid meteors is a dirty ice ball named Comet Kiess, a long period comet discovered in 1911. Comet Kiess takes about 2,000 years to circuit the sun in its long, looping orbit. Meteor scientists have determined that, prior to 1911, Comet Kiess passed through the inner solar system in the year 82 B.C., when Julius Caesar was just a young man. It was the ribbon of dusty debris shed by Comet Kiess during that pass in 82 B.C. that brushed against the Earth and caused the unexpected meteor outbursts in 1935, 1986 and 1994.
Peter Jenniskens of NASA's Ames Research Center in Moffett Field, Calif., has modeled this 82 B.C. dust ribbon and has determined it might collide with the Earth just before dawn on the morning of Sept. 1. "Might" is the key word because meteor forecasting is a young science. Folks living along the West Coast of the U.S. and those in Hawaii and Alaska have the best seats for the possible fireworks, as sunrise will not have brightened their skies at the time of the predicted peak.
The meteors will compete with a very bright waning gibbous moon that morning, but if past performances are any gauge, the meteor shower, if it develops, shouldn't be diminished. Estimates of the numbers of meteors range from 30 to 300 meteors per hour for a brief time centered on 5:36 a.m. Many of them should be bright and leave long, glowing trails.
For most meteor-watching enthusiasts like me, even a slim chance of seeing a rare outburst of bright meteors is more than enough reason to get up a little early Sept. 1. The blue-green-colored meteors should be visible over the entire sky, but they will all trace back to a common point in the northeastern sky near the bright star Capella, also called Alpha Aurigae.
After this year, the meandering dust ribbon is not likely to encounter the Earth again for at least 70 years, so, be a part of history. Get out there and see if the first predicted storm of Alpha Aurigid meteors actually happens!
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 on the Web sites of CNN.com, NASA's "Astronomy Picture of the Day," Spaceweather.com, Space.com, Discover.com, , NationalGeographic.com, and in Sky & Telescope, Astronomy, Night Sky, Discover, and WeatherWise magazines.