Jimmy Westlake: Great balls of fire
October 29, 2012
Don't be surprised if you see a blazing fireball or two streaking across the heavens while you are out trick-or-treating this week. There's no reason for alarm — it's just the annual Taurid meteor showers reaching their peak of activity.
The Taurid meteors are so named because they seem to spring outward from the stars of the constellation of Taurus the Bull, rising in the east as darkness falls in late October and early November. The source of the Taurid meteors has been traced back to a comet named Encke (pronounced "inky"), after the astronomer who first calculated its orbit around the sun, Johann Franz Encke, in 1819. Astronomers now suspect that Comet 2P/Encke is just a fragment of a much larger body that crumbled into pieces thousands of years ago. The orbit of Comet Encke, with its trail of dusty debris, passes close to the Earth's orbit in early November. Some of those cometary fragments rain down into Earth's atmosphere traveling about 17 miles per second. This causes the fragile particles to burn up about 60 miles above the Earth's surface as they plow through our protective atmosphere.
Sometime in the distant past, Comet Encke's debris stream passed close to the giant planet Jupiter and was split into two parallel branches, the South Taurids and the North Taurids. The South Taurid meteors peak around Nov. 5, and the North Taurid meteors peak about a week later, around Nov. 12. But a few Taurid meteors can be seen anytime between Sept. 25 and Nov. 25. While you can see the Taurid meteors in all parts of the sky, their trails will all point back toward the little Pleiades, or Seven Sisters, star cluster in Taurus.
This isn't a particularly rich shower of meteors — you'll see only a half-dozen or so Taurids per hour. But what it lacks in numbers it makes up for in bright fireballs.
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.