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New Mexico State University

New Mexico State University

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Meteor shower should present early-morning display of 'shooting stars'

The Leonid meteor shower should present New Mexicans with a nice early-morning display of "shooting stars" on Wednesday, Nov. 19, said New Mexico State University astronomer Kurt Anderson.

wer is expected to peak around 12:30 a.m. Mountain Standard Time, with a peak rate of 30 to 100 events per hour. The rate is expected to be much lower an hour before or after the peak of activity.

"Although the predicted rates are somewhat lower than was seen in November 2002, many of the fainter meteors were lost in the light of the full moon last year," Anderson said. "This time the moon will be in a waning crescent phase so the more numerous fainter meteors should be visible."

Observers should select a dark location with an unobstructed view of the eastern sky. The constellation Leo (the Lion) will be rising in the east and the Leonid meteors will appear to radiate outward from the sickle-shaped group of stars that make up the head of the lion. The bright star Regulus is at the base of the sickle.

Anderson said Leonid meteors are produced every year at this time when the Earth crosses the path of Comet Tempel-Tuttle. The comet orbits the sun every 33 years and during each passage through the inner solar system some of its icy material vaporizes to form the cometary tail. Icy grains and other solid materials also leave the main body of the comet, leaving a trail of debris in Tempel-Tuttle's orbit.

At this time the Earth happens to be moving in its orbit toward the region of the celestial sphere occupied by the stars that make up the constellation Leo.

"Our orbital speed is about 18 miles per second. For that reason, the meteors seem to be radiating from that direction in the sky; hence this annual shower is called the Leonids," Anderson said. "The morning half of the Earth is always the side of the Earth facing our direction of orbital motion. This is why meteors of all kinds are observed more frequently during early morning hours."

Meteor showers are predictable and regular annual events. Each consists of debris associated with a known periodic comet. On the other hand, the so-called sporadic meteors -- which can be seen every night -- are mostly tiny fragments of asteroid material, Anderson said.