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Leonid meteor shower predicted to be spectacular

The Leonid meteor shower should present New Mexicans with a spectacular early morning display Tuesday, Nov. 19, said New Mexico State University astronomer Kurt Anderson.

play is expected to peak between 3:30 and 4 a.m. The light of the full moon will hide many of the fainter meteors, but the Leonid shower will have many brighter meteors, Anderson said.

Forecasts suggest that between 100 and 300 of these brighter meteors will be observed during the 15 minutes of peak activity. The rate is expected to be much lower an hour before or after the peak of activity. This meteor shower might better be described as a meteor "storm" because of this high peak rate, Anderson said.

Leonid meteors are produced every year at this time when the Earth in its orbit around the sun crosses the path of Comet Tempel-Tuttle. This comet orbits the sun every 33 years. 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 debris trail of particles in its orbit.

These "litter" particles are responsible for the meteor shower we see every November. At the time of the shower 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 the Lion. Earth's 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, he said. The constellation Leo will be high in the southeastern sky during the shower peak. "Look for the brilliant planet Jupiter, with the bright star Regulus just below it," Anderson said.

Meteor showers are predictable and regular annual events. Each consists of debris associated with a known periodic comet. In comparison, sporadic meteors, which can be seen every night, are mostly tiny fragments of asteroidal material, he said.

The debris in the orbit of Comet Tempel-Tuttle is distributed in a clumpy fashion and this year's Leonids will occur as the Earth encounters a pair of these clumps. This is why an unusually spectacular display is expected, Anderson said.

The first clump will be encountered in the early morning hours for European observers. The Earth will encounter the second clump about eight or nine hours later, making the southwestern United States, with its clear dark skies, the best observing location, he said.

A group of NASA meteor forecasters will be at Apache Point Observatory in the Sacramento Mountains to electronically record the Leonid shower. NASA is interested in meteors and forecasting meteor activity because of the potential threats of meteoroids to satellites and spacecraft, Anderson said.

Rob Suggs, leader of the NASA Space Environments Team, which will conduct these observations, is a graduate of New Mexico State's Astronomy Ph.D. program. Apache Point Observatory is operated by New Mexico State for a consortium of universities.

For more information about Apache Point Observatory visit http://www.apo.nmsu.edu. For more information about NASA visit http://science.nasa.gov.

Nov. 12, 2002