Astronomers watch one-two-three punch of comet into Jupiter's atmosphere

July 21, 1994|By Frank D. Roylance | Frank D. Roylance,Sun Staff Writer

Astronomers around the world were waiting for the third "shoe" to drop today as the last of a trio of comet fragments headed for splashdown in the same area of Jupiter.

Reports reaching the Goddard Space Flight Center this morning said that the first -- fragment Q2 of comet P/Shoemaker-Levy 9 -- struck on schedule about 3:45 p.m. yesterday.

Fragment Q2 was accompanied by a fragile companion, Q1, which fell nearby, making a barely discernible mark on the Jovian cloud tops. Scientists today dubbed it a "Q-let."

The second sizable member of the trio fell about 10 hours later, after the planet had rotated through one of its brief days. It was spotted from Flagstaff, Ariz., by Dr. David Schleicher at the Lowell Observatory.

He reported seeing the flash after 1:30 a.m. EDT today as fragment R shot through Jupiter's upper atmosphere as a giant meteor. "That may mean it was a bigger piece than people had anticipated," he said.

The flash was also witnessed by Dr. Imke De Pater at the W.M. Keck Observatory in Hawaii. "The flash from R lasted 20 seconds, and the plume [a fireball of hot gas rising from the impact site] appeared eight minutes later," she said. In another eight minutes, it had faded from sight.

The last of the trio of fragments -- S -- was due to strike the same region of Jupiter one more 10-hour Jovian day later, late this morning, Baltimore time.

Scientists were eager to learn what effects there might be from three hits at almost the same spot.

In all, about 16 fragments of the comet have struck Jupiter since the barrage began on Saturday. Including S, five more were still to fall by about 4 a.m. tomorrow.

Scientists said the Galileo spacecraft, en route to Jupiter and now about 150 million miles away, has had a direct view of the impacts, which have occurred on the back side of the planet, just out of sight as seen from Earth.

The Jet Propulsion Laboratory in Pasadena, Calif., has reported that signals from Galileo indicate that its instruments have recorded the flashes and fireballs.

Astrophysicists hope to use the full series of Galileo's observations to make direct comparisons of the relative power of each impact. No photos are expected from the spacecraft for several months, however, because Galileo's high-speed antenna is not working.

The bombardment of Jupiter by the comet is revealing chemicals that scientists say might explain for the first time the yellows, reds and browns of the planet's visible clouds.

Delighted astronomers also reported yesterday that they have seen the equivalent of northern lights on Jupiter, but at latitudes farther south than they have ever been seen before. It's an effect they think is caused by the falling comet.

But none of their discoveries or computer enhancements, they say, can match the thrill of putting their eye to a small telescope and seeing the dark impact sites for themselves.

The spots -- Earth-sized clouds of gas and dusty debris blown into Jupiter's stratosphere by the comet impacts and explosions -- are the biggest changes and the most prominent features to appear on Jupiter since Galileo started looking in 1610. Astronomers are urging everyone to find a telescope and have a look.

"This is an extraordinary thing," said David Levy, co-discoverer of Shoemaker-Levy 9. "These spots are a major effect from these collisions. They're easy to see [with modest telescopes and good visibility], and this is the time to do it."

University of Maryland astronomer Lucy McFadden, who is coordinating the worldwide observations, stood in line Tuesday night to view Jupiter through an 8-inch amateur telescope at the UM observatory in College Park.

"There's something visceral about putting your eye to an eyepiece," she confessed. "I took my husband, and he said it was sort of a 'Woodstock' experience.

"I could see the [planet's cloud] bands going across and sort of convinced myself I could see some spots."

Later, through the university's 20-inch telescope, Dr. McFadden said, "I actually saw those spots." A video monitor linked to the telescope showed three impact sites. "I could only discern two with my eyeball."

An estimated 500 people trooped through the College Park observatory Tuesday night to have a look.

The UM observatory's open house has been extended through tomorrow night. Located near University Boulevard and and Metzerott Road, the observatory is open from 8 p.m. to 10 p.m.

The Jupiter watch also continues from 8:30 p.m. to 1 a.m. through tomorrow night at the Johns Hopkins University's Bloomberg Physics Center, near the San Martin Drive entrance of the Homewood campus.

Eighty to 100 people have visited the center each night since the comet show began. Call 516-6525 after 5 p.m. for weather updates.

The discovery of sulfur at the spot where fragment "G" crashed down Monday morning was reported yesterday at the Goddard Space Flight Center in Greenbelt by University of Arizona astronomer Roger Yelle.

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