Trail Gazer : Amateur Newcomer to Astronomy Discovers Potentially Spectacular Comet : SCIENCE FILE / An explosion of issues and trends affecting science, medicine and the environment

GLENDALE, Ariz. —  Less than four months ago, warehouseman Thomas Bopp was laboring in obscurity on the night shift at a paving materials company. He spent his weekends stargazing through the telescopes of friends in the Arizona desert 50 miles west of the Phoenix city lights.

Then, just before midnight July 22, he peered through the eyepiece of a telescope that a friend had made of birch boards and aluminum tree-trimming tubes. There, he saw a faint, hazy globe of light drifting across the field of view.

Today, the shy 45-year-old’s name rides on that puff of distant light, a comet that scientists believe may be the most spectacular in decades when it passes near the sun in the spring of 1997. Bopp shares the honor with astronomer Alan Hale, who saw the comet almost simultaneously in New Mexico.

Of the five to 10 comets discovered each year, many are found by amateur astronomers using relatively low-power telescopes. But in the world of comet hunters, where persistence and vigilance are rewarded by naming rights for their discoveries, Bopp is a man of distinction: A newcomer to the field, he does not own a telescope and wasn’t even looking for a comet when he hit the celestial jackpot.

Comet Hale-Bopp is among the largest ever recorded, experts say. Estimated to be 30 to 90 miles in diameter and now lurking just beyond Jupiter on its way toward our sun, Hale-Bopp is being compared to the so-called Great Comet of 1811, which Tolstoy described in “War and Peace”:

“The radiant star which, after traveling in its orbit with inconceivable velocity through infinite space, seemed suddenly--like an arrow piercing the earth--to remain fast in one chosen spot in the black firmament, vigorously tossing up its tail.”

Today’s astronomers won’t promise such poetic visions, but they do believe it will be seen easily with the naked eye across the Northern Hemisphere. Its brilliance is expected to be at least as bright as the planet Jupiter with a long, luminous tail.

That, however, is what astronomers said about Comet Kohoutek, which in 1973 was predicted to be the “Comet of the Century.” Kohoutek proved a dud, barely visible to the naked eye when it passed near the sun that year. What astronomers did not realize about Kohoutek at the time was that it was making its first pass around the sun after being tugged from a frigid region far beyond Pluto called the Oort Cloud. Scientists believe as many as a trillion comets--icy remnants of the very building blocks that formed the planets--spin endlessly in the Oort Cloud.

In Kohoutek’s case, scientists now believe that the comet’s initial brightness was due to solar heat boiling off an unusually large amount of glaze of frozen carbon dioxide and monoxide gases on its surface. That temporary burst of light fooled astronomers into thinking it was larger than the six miles in diameter it was estimated to be. Comet Hale-Bopp will be different, astronomers say, because in calculating its orbit, they know that it has been around the sun before and has survived similar encounters intact. The comet is extremely bright now, even 600 million miles from the sun, said Brian Marsden, associate director for planetary sciences at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. This gives him and others reason to believe it is packed with ice and dust, which will evaporate as it nears the sun, creating a long, luminous tail.

Astronomers recently traced the path of Hale-Bopp, which they now believe orbits our sun once every 3,000 years. They also found its image on a photographic plate taken in Australia in 1993. Even then, Marsden said, it was unusually luminous, indicating that it probably survived earlier passages near the sun and that its current brightness is not a tease.

“This comet has the potential of being spectacular,” said Donald Yeomans, a senior research scientist at the Jet Propulsion Laboratory in Pasadena. Still, he cautioned, “the hope is that this comet is for real and not giving off a veneer. But we must remember that nature can always thumb her nose at us.”

Bopp, meanwhile, is hoping for the best. “It’s so far out right now that a lot could happen--it could fall apart,” he said. “But I think it’s going to be a monster. After all, Brian Marsden is excited about it, and he doesn’t get excited about these things very often.”

Bopp’s life changed when he and his friend, Jim Stevens, 53, were observing the star clusters in the vicinity of the constellation Sagittarius with Steven’s homemade 17 1/2-inch reflector telescope.

They were admiring the star cluster known as M-70 when Stevens stepped away to consult a star chart for another object to scan, and, not incidentally, to turn up the volume on a tape of his favorite Irish musical group, the Chieftains. That is when Bopp took his peek and noticed the fuzzy blob.

“Hey, Jim. What’s this?” he asked, moving aside to let Stevens look.

“Gee, dunno,” Stevens told him. “Let’s check the star atlas.”

Under the soft red glow of a penlight, they couldn’t find the mysterious light on any of the four star charts they spread across the hood of Steven’s car. That’s when they began to get excited.

“I thought it might be a comet,” Bopp said, noting that he had seen a fuzzy blur rather than a sharp point of light that could have been a star. “And I said a silent prayer, thanking God for all the beautiful things up there in space,” Bopp recalled.

He sped the 40 miles to his home in the Phoenix suburbs and, shortly after midnight July 23, he reported the finding by telegram to the Central Bureau for Astronomical Telegrams in Cambridge, Mass., which acts as a clearinghouse for newly discovered space objects. The next day, the bureau called and confirmed that there was no known celestial body in that position and that Bopp had indeed discovered a previously unknown comet.

They also told him that Alan Hale had reported seeing the same comet about the same time while stargazing in his driveway in Cloudcroft, N.M., about 500 miles to the east.

“I let out a whoop and holler when I got off the phone,” Bopp recalled recently. “My wife says I was dancing around like a crazy man in the dining room.”

Now, at his job, Bopp’s co-workers frequently give him a military salute and shout “Hail Bopp!”

“I don’t mind a bit, although I’m not used to all the attention,” he said.

Bopp and Hale, who heads the Southwest Institute for Space Research near Alamogordo, N.M., have been deluged with invitations to speak about the comet.

For now, though, Bopp and his telescopic companion Stevens are keeping tabs on the cosmic visitor on weekly visits to their favorite desert viewing site.

During a recent viewing, Bopp stepped back to ponder the wonder of it all.

Once, comets were regarded as signs of God’s wrath, Bopp said. Now, astronomers believe that swarms of these loosely packed dirty snowballs bombed the Earth eons ago delivering most of the planet’s water in the process.

“Imagine, Hale-Bopp was last here around the time of King David,” Bopp said, staring skyward at the Milky Way. “Always ethereal and haunting.”

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Brilliant Traveler

Comet, Hale- Boop, which orbits the sun about once every 3,000 years,is expected to put on a spectacular light show when it nears the sun in 1997 (it will reach its closest point to the sun in April, 1997). Its orbit extends roughly 10 times the distance of Neptune from the sun, about 30 billion miles.