Originally created 12/14/01

Meteor shower offers breakthroughs in forecasts



An intensive effort to record and analyze last month's Leonid meteor shower is paying off in some unexpected ways, scientists say, including a much-improved ability to forecast future spectacles.

In a replay of one of the most thrilling celestial events in recent memory, professional meteor trackers gave a meeting of scientists in San Francisco a close-up view Tuesday of just what was happening as thousands of comet specks flared across Earth's atmosphere.

"We are really getting a handle on meteor showers as an astronomical phenomenon, so meteor showers have gone from anecdotal events seen by few to a space-weather phenomenon that you can confidently predict," said Peter Jenniskens, principal investigator for a NASA airborne laboratory that watched the Leonids from above cloud cover.

Another Leonid show is expected to peak during the early morning hours next Nov. 19 - and now promises to be just about as awesome a display as this year's, billed as the best of a generation.

Jenniskens, who led a panel of Leonid experts at the American Geophysical Union annual meeting, says he discounts predictions of a skywatching letdown in 2002.

One problem is that the moon will be full for the next pass through the tail of the comet that generates the Leonids. That's in contrast to the new-moon conditions that helped make for a gloriously dark backdrop last month.

But the full moon "shouldn't scare people away," Jenniskens said, because it will be out of the way for most U.S. viewers during the peak hours.

Besides better forecasting, scientists also gleaned new insights into the obscure physics and chemical events that occur as meteors gradually are pecked apart when they hit air molecules in the upper atmosphere.

A high-speed camera used by geophysicist Hans Stenbaek-Nielsen of the University of Alaska at Fairbanks snapped 1,000 frames a second of "ablation zones" - growing clouds of meteoric plasma and dust whose hot glow generates the impression of "shooting stars" in a night sky.

Those pictures, along with other chemical and spectroscopic data, gave the first detailed view of what actually happens when a meteor comes along.

"For the first time we've been able to probe into what was before sort of a black box," Jenniskens said, noting the process was far different from the "melting" that many had conceived.

Witnessing the breakup of meteors as it happened also promises to bring further insight into where meteoric debris ends up, either drifting down into the ocean or dissipating in space.