1999 Leonids Have Astronomers Starry-Eyed

Thirty-three Novembers ago, Joe Rao stood in his Bronx backyard, cursing the heavens.

Clouds covered the midnight sky like a fresh coat of plaster, smearing the 10-year-old’s view of the annual Leonids meteor shower.

Rao’s parents and neighbors had long since trudged to bed. But the boy persisted, bundled up as if he were going tobogganing, his ear glued to an AM transistor radio.

Chicken Littles filled the late-night airwaves with descriptions of shooting stars drenching the cosmos like a celestial typhoon and, perhaps, ending the world.

It was the now-famous 1966 Leonids meteor storm.

And Joe Rao was missing it.

“It was the first time I stayed up all night,” recalled Rao, who lectures at New York City’s Hayden Planetarium. “I was tearing my hair out.”

This may be the year that Raofinds meteor redemption.

The Leonids occur every year on or about Nov. 18. Earth glides through the diaphanous tail of Comet Tempel-Tuttle and stargazers are tempted with a drizzle of 10 or 20 meteors fizzing across the horizon every hour.

But every 33 years, astronomers calculate, a rare and dazzling Leonids storm can occur after the comet swoops near the sun, shrugging off layers of dusty, icy particles the size of Rice Krispies. Earth plows straight through the comet’s refreshed wake.

Astronomers believe the 1999 edition of the Leonids probably won’t equal 1966, which peaked at 144,000 meteors per hour. But it is likely to be a meteor gully-washer at 2,000 to 6,000 meteors per hour. Maybe more.

A meteor poses no real danger. A meteor actually refers to the bright streak of light that is generated by friction as the comet particle rips through earth’s thick atmosphere at 40 miles per second.

The particle, known as a meteoroid, sheds its own outer layers of molecules with a Technicolor brilliance before its core is vaporized. (A few meteors also are caused by fragments shed by passing asteroids, but they don’t trigger annual showers.)

Still, operators of 600 satellites are taking no chances. They are diverting their “birds’ ” sensitive optics and antennae so the incoming particles won’t disrupt everything from cell-phone and cable-TV signals to military observations. NASA has postponed its next space shuttle mission until after Nov. 19.

“The likelihood of getting hit goes up, and protecting satellites becomes very important,” said William Ailor of the Aerospace Corp. in El Segundo. “But losing a number of satellites in the storm is out of the question.”

On the ground, the Leonids are a reason to party. Sky watchers defy frosty temperatures and drag out lawn chairs for the spectacle. Planetariums are hosting Leonids cruises and camp-outs.

And this year’s observations could turn out to be more precious still.

Irregularities in Earth’s orbit and Jupiter’s powerful gravitational tug are likely to jostle Tempel-Tuttle slightly off course for an orbit or two, resulting in diminished Leonids encounters for up to 100 years.

That doesn’t mean there won’t be other meteor showers in the 21st century. The Perseids occur every Aug. 12, and the Geminids in mid-December.

But none can match the Leonids in a storm year. That’s why Rao’s enthusiasm hasn’t dimmed.

“I’ve seen just about every manner of glorious spectacle--eight total eclipses of the sun, the aurora borealis, comets,” Rao said. “The one thing I haven’t seen is a storm of meteors.”

“It’s one of the biggest disappointments of my life,” he said. “This Leonids may be my last chance.”

The best Leonids viewing this year, weather permitting, probably will be in Europe, the Middle East and North Africa.

Views in the United States are likely to be marginal by comparison, but still worth a look. The night skies still should appear busy, with a tenfold increase of “shooting stars” compared to a typical Leonids shower.

Wherever you live, astronomers recommend looking toward the eastern sky beginning Wednesday, Nov. 17, between 10 p.m. and midnight. Binoculars and telescopes aren’t necessary. The phenomenon is called the Leonids because the incoming particles appear as if they are emanating from the constellation Leo.

Scientists’ plans are more ambitious, however.

Researchers are lugging ground-based instruments to isolated locations throughout the Mediterranean and the Middle East, even the dunes of the Sahara.

NASA and the Air Force will mount a joint air campaign to study the behavior, chemical composition and potential biology of the incoming debris.

A pair of instrument-rigged jets will soar above the clouds and urban air pollution to analyze and photograph the Leonids over Europe and North Africa on Nov. 17-18.

Last year, the aircraft chased the Leonids over East Asia to analyze the extraterrestrial particles’ chemistry and biology. Some scientists believe water, organic molecules and other components necessary for life were express-delivered to Earth by comets and other space projectiles.

The temperature of Leonids particles was lower than expected as they streaked through the atmosphere at a rate of 250 per hour.

“They heat up, but they cool off very quickly,” said Peter Jenniskens of NASA-Ames Research Center in Mountain View, Calif.

Also, the carbon-based compounds survived their hellish rides deep into the atmosphere.

“It suggests that organic material can come into the atmosphere and survive, to some extent,” Jenniskens said.

This year, NASA’s Leonids flights will examine the particles in more detail using an infrared spectrometer. The light from each particle reveals the particle’s unique chemical signature.

Aloft, Jenniskens said, meteors appear to trace slow arcs, making them easier to track across the horizon.

But he professes to envy backyard observers--at least on a clear night.

“When you’re flying, we can only look out of the plane’s little windows,” he said.

From NASA’s Marshall Space Flight Center in Huntsville, Ala., researchers will float a balloon to nearly 20 miles high and beyond 98% of the atmosphere. Included in the instrument payload are panels of an ultralight, translucent material called xerogel.

Researchers hope it will gently capture an actual piece of what crooners romantically, but inaccurately, call stardust.

“It works like flypaper,” said NASA astronomer John Horack. “When particles strike the exposed xerogel, they stick.”

Meteor showers rarely behave predictably. Cosmological handicappers are laying bets across the celestial board this year.

Donald K. Yeomans of the Jet Propulsion Laboratory says the heavens are lining up in a geometric pattern most similar to those that produced the Leonids showers of 1866-67 and 1931-32.

Those years saw showers of 5,000 meteors per hour, and “we might anticipate a rate in 1999 bounded by the rates in the earlier events,” Yeomans says. The peak? Yeomans cites this Thursday, Nov. 18, at 1:48 a.m. London time.

Astrophysicists in Canada, Great Britain and Australia offer a more sober prediction of 1,500 per hour, peaking on Nov. 18 at 2:08 a.m. London time.

And Rao? He has mined 10 centuries of astronomical records and found descriptions of 10 or 12 significant Leonids events dating to ancient Chinese dynasties.

Meteor storms, Rao calculates, often occur 600 days after Comet Tempel-Tuttle has swept across Earth’s orbit.

The comet last cruised through Earth’s neighborhood on March 5, 1998. Last year’s shower occurred 257 days after the intersection.

This year, Earth will be 623 days behind Tempel-Tuttle. It will result in a vigorous 6,000 to 20,000 meteors per hour, he predicts.

This year the stakes are too high for Rao to risk being blinded by more backyard clouds. He is leading 75 amateur observers about 4,000 miles east of the Bronx, to a volcanic outcrop in the Canary Islands northwest of Africa.

The weather report? Dark and dry, but no guarantees.

Lightshow on the Web

Leonids sites on the World wide Web providing frequent updates and live videos:

* NASA-ames Research Center: www.leonids.arc.nasa.gov

* NASA-Marshall Space Flight Center: www.LeonidsLive.com

* Aerpspace Corp.: www.Leonidstorm.com