Leonid showers to rain over North America

larger   Photo of a 1966 Leonids storm

By Richard Stenger
CNN.com Writer

(CNN) -- Leonid meteors could sprinkle the skies with dazzling streaks of light before dawn Friday and Saturday. Some astronomers predict the shower will deliver a spectacular display over North America.

Others fear the annual rain of comet debris will not live up to the spectacle of recent years. Even if it did, a bright moon near the heart of the shower will likely take much of the celestial spotlight.

Still, scientists remain uncertain about just what to expect this weekend. The Leonids, which appear every year around November 16 to 18, are among the least predictable of the annual meteor rains.

Despite using improved prediction methods, professional star watchers disagree on what to expect.

European astronomers expect two peaks on the morning of November 17. They predict anywhere from 100 to 900 Leonids per hour during peak times. One alternative model suggests that the meteor rate may reach 5,000 per hour, with a slight chance that it may briefly soar to 50,000 per hour.

Europe will likely miss much of the light show, but people in North America should have prime viewing after midnight and before dawn to watch the showers.

U.S. meteor specialist Joe Rao said that November 18 could be this year's "Leonid Wild Card." He and others think that Saturday morning before dawn could offer the best viewing for peak showers.

Unfortunately, only the brightest fireballs will be visible, regardless of when the peak takes place. The last-quarter moon will be near the Constellation Leo and blot out fainter meteors.

Those hoping to view the shower should look away from the moon and towards the Big Dipper, or stand where a building or other obstruction hides the moon from view.

The Leonid shower is named after the constellation of Leo, the region in the heavens from which the meteors seem to originate. Actually they come from a thin dust stream of tiny meteors, ejected over the centuries by Comet Tempel-Tuttle as it passes near the sun.

The debris is sprinkled along the orbit of the comet in a trail of dust, and the Earth passes through or near the meteoroids every November. As particles the size of dust or sand grains burn up in the atmosphere, streaks of light sometimes called shooting stars race across the skies.

Severe Leonid showers happen about every 33 years and sometimes are so intense they qualify as meteor storms. They occur when the Earth goes through an unusually dense stream of comet debris, often associated with increased solar activity. One such storm happened in 1996.

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Leonids 2000 (ESA page)
Leonid predictions for 1999-2006
Lunar Leonids 2000

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