1. Monday, November 18, 2002

    the stars are coming out, will you see them? 

    from JPL News today.

    The early morning hours of Nov. 19 (late tonight) may be your last chance to see the spectacular Leonid meteor shower in its full glory, according to astronomers.

    “Even with the full Moon, this year’s Leonids will probably be better than any other for the next hundred years,” said Dr. Don Yeomans, an astronomer at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “If you’re ever going to see them, this might be the year to try.” NASA is taking advantage of the event for several research efforts around the world.

    The shower is predicted to have two peaks, each a couple of hours long, during which the most meteors can be seen. The shower’s second peak, most prominent in North American skies, is expected at around 2:30 a.m. (Pacific time) Nov. 19, and promises the rare spectacle of a few meteors every minute or even more. “Observers in good locations away from city lights might see a few hundred per hour. You’ll only get to see the bright ones because the moonlight will wash out the ones that aren’t as bright,” said Yeomans. Last year, observers did not have to contend with the Moon and saw meteors at a pace of several hundred per hour.

    An earlier peak is expected over Europe and Africa the night of Nov. 18, and observers in North America might see a few grazers — meteors skimming the top of the atmosphere — from this first peak starting around 8:30 p.m. (Pacific time) Nov. 18.

    The Leonids are grains of dust from comet Tempel-Tuttle colliding into Earth’s atmosphere. Most Leonid particles are tiny and will vaporize very high in the atmosphere due to their extreme speed (about 71 kilometers or 44 miles per second), so they present no threat to people on the ground or even in airplanes. As it progresses in its 33-year orbit, the comet releases dust particles every time it comes near the Sun. Earth intersects the comet’s debris trail every year in mid-November, but the intensity of each year’s Leonid meteor shower depends on whether Earth ploughs through a particularly concentrated stream of dust within the broader debris trail.

    The dust that Tempel-Tuttle shed in 1866 makes up the stream predicted to give Americans a good show this year. Last year, people in Asia saw the plentiful collisions within that stream. A dust stream from 1767 provided last year’s peak hour of viewing in North America and will provide this year’s peak hour of viewing in Europe. After 2002, Earth won’t hit either of those streams again for decades to come, and is not predicted to encounter a dense Leonid stream until 2098 or 2131.

    The golden rule for watching the Leonids — or any meteor shower — is to be comfortable. Be sure to wrap up warmly — a sleeping bag placed atop a lawn chair facing east is a good way to enjoy the show. Put your chair in a clear, dark place with a view of as much of the sky as possible. Don’t stare at any one place. Keep your eyes moving across the sky. Most Leonids will appear as fleeting streaks of light, but watch for the bigger ones that produce fireballs and trails. Some trails will remain visible for several minutes or more.

    scienceblog