Comet's chunks are zeroing in on Jupiter

May 19, 1994|By New York Times News Service

Most of the world's telescopes on the ground and in space will be pointed at Jupiter this summer, watching for a cosmic collision that is certain to happen and waiting to give scientists their first view of the kind of catastrophic event that may have accounted for mass extinctions on Earth long ago and the eventual emergence of humans.

A comet, now shattered into at least 21 icy chunks, is zeroing in on the largest planet in the solar system.

Scientists have been tracking the course of the comet, Shoemaker-Levy, for more than a year.

The first huge fragment, perhaps a mile or two in diameter, is expected to plow into Jupiter's dense atmosphere July 16. Then, one after another over the next six days, the remaining chunks should plunge into the Jovian atmosphere.

The impacts will occur on Jupiter's far side, but at least one American spacecraft may catch glimpses and other telescopes should observe reverberating aftereffects in the planet's atmosphere: puffs of white clouds or even roiling storms in the manner of the Great Red Spot. Or the effects could also be seen in the surrounding environment: flashes of explosive light perhaps reflected off the Jovian moons.

In describing their predictions and observation plans in Washington, the scientists conceded that given their primitive knowledge of comets, they might be in for many surprises.

"We know it's going to hit, and we know the atmosphere of Jupiter is going to react in some way to that," Dr. Heidi Hammel, an astronomer at Massachusetts Institute of Technology, said of the comet. "How Jupiter reacts, that's what is going to be so interesting to us."

Depending on the eventual size of the fragments at impact, the scientists said, the combined energy of the collisions could exceed the power of all the world's nuclear arsenal.

"For the first time ever, we have been able to predict a major collision in advance and plan to observe it," said Dr. Eugene Shoemaker, a planetary scientist at the U.S. Geological Survey in Flagstaff, Ariz. "I will be personally astonished if we don't observe something."

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