Jimmy Westlake: The fireballs of fall


Comet Holmes update

Comet Holmes remains an easy naked-eye target in the early evening sky this week after its extraordinary outburst on Oct. 23. Look toward the constellation Perseus, about one hand-span below the familiar W-shaped constellation of Cassiopeia, high in the northeastern sky after sunset. Comet Holmes looks like a bright, hazy star to the naked eye. Aim your binoculars at it and, "Wow, what a sight!"

As you gaze up at the starry sky in early November, don't be surprised if you see a blazing fireball or two streaking across the heavens. There's no reason to be alarmed, it's just the annual Taurid meteor shower reaching its peak of activity.

The Taurid meteors are so named because they seem to radiate outward from the stars of our constellation Taurus the Bull, rising in the east as darkness falls. The source of the Taurid meteors has been traced back to a comet named Encke that astronomers suspect is just a fragment of a much larger body that crumbled into pieces thousands of years ago. The orbit of Comet Encke and 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 incinerate about 60 miles up 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 around Nov. 12.

This isn't a particularly rich shower of meteors - you'll only see a half-dozen or so per hour. But what it lacks in numbers it makes up for in pizzazz. The November Taurid meteors are some of my favorites to watch because they tend to be big, bright and slow - so slow, in fact, that you might have enough time to alert your fellow sky watchers to a meteor by yelling "Look!" before the meteor disappears. I often see them out of my car window in early November, dropping toward the horizon when I'm driving home after dark. With the new moon falling on Nov. 9 this year, the early November sky will be moonless and perfect for meteor watching. It's almost like having the Fourth of July in November with Mother Nature and Comet Encke providing the fireworks!

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" website, Spaceweather.com, Space.com, Discover.com, MSNBC.com, NationalGeographic.com, and in Sky & Telescope, Astronomy, Night Sky, Discover, and WeatherWise magazines.


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