leonids
Image: NASA-ARC; COURTESY OF NHK
This weekend's blockbuster isn't showing at a theater near you. Instead, it's in the predawn sky on Sunday, November 18th. In the wee hours that day, the Leonid meteor shower will put on its best show since 1966. And if you miss this year's attraction, there won't be another like it for decades.

The Leonid meteor shower occurs when earth passes through debris left behind by the comet Tempel-Tuttle, which last passed close to the sun in 1998. The Leonids take their name from the fact that they appear to originate from the constellation Leo. But the meteors are actually bits of dust and rock shed by the comet during its 33.25-year journey around the sun. When these particles, traveling at 160,000 miles per hour, come into contact with the earth's atmosphere, they vaporize and leave streaks of light that are visible to the naked eye. Astronomers predict that the meteors will be darting across the sky at a rate of 1,000 to 2,000 an hour. Such peak activity is expected to occur between 4:00 a.m. and 6:00 a.m. EST on Sunday for viewers in North America.

A slightly less sensational spectacle is predicted for 2002 when the shower will occur under a full moon. After that, it will be nearly a century before the next impressive display. "It's now or never," Robert Naeye of the Astronomical Society of the Pacific says. "We will probably never see a better meteor shower in our lifetimes."