Planet Wars

Last year, two Bay Area astronomers said they had discovered planets outside our solar system and became instant media celebrities. Now, Paul Butler and Geoff Marcy face prominent scientific challengers who contend some of the new planets are nothing but

Challenges to Marcy and Butler run along two general lines, based on alternate interpretations of subtle wobbles the two astronomers have detected in several stars' paths across the night sky. Butler and Marcy say stars wobble because of the gravitational pull of orbiting planets.

The Canadian researcher disdained by Marcy, however, believes the wobbles may come from physical changes in the stars themselves.

A second challenge suggests that such wobbles are created by the gravity of unseen sister stars, locked in orbit with their visible siblings. In these binary systems, the stellar companion is so close to its twin as to be invisible to all but the most specialized telescopes, this theory maintains.

These disputes cannot be solved by direct observation, because no telescope can actually "see" a planet at the distances involved. Stars emit millions of times more light than is reflected from planets, which are not themselves light sources; trying to see a far-off planet, therefore, is somewhat like trying to discern the features of a night driver's face while staring into oncoming headlights.

New measurements, however, do seem likely to settle much of the controversy surrounding the Butler-Marcy planets, and fairly quickly.

To help reach that settlement, an unlikely hero has emerged in the person of everywoman astronomer Sallie Baliunas. She's organizing astronomers across the continent to coordinate their observations, in hopes of bringing a quick answer to some of the questions raised by the challengers to Butler and Marcy.

Baliunas believes that such a collaboration can provide at least a tentative answer to one of life's great questions: Are we alone in the universe?

"I call it the second-most-interesting question there is; the first is, 'Does God exist?' " says Baliunas, sitting before a computer terminal in the observing room of the retrofitted, turn-of-the-century, 100-inch telescope at Mount Wilson, near Los Angeles.

"I suppose there are more important questions -- a cure for cancer, that sort of thing. But none are more interesting."

Cinderella Story
Challenges to the work of Butler and Marcy mark a departure from what had been one of science's great Cinderella stories.

Ten years ago, the scientists were considered obscure researchers from a second-rate college; in January of last year, they became world-renowned pioneers in one the most attention-grabbing areas of scientific research.

As is the case in many scientific discoveries, their success benefited from ingenuity, luck, and a lot of perseverance.

"What's so delightful, I think, is that they're at what a lot of people would consider to be a third-rate place. S.F. State is not a Stanford or a Berkeley," says Steve Vogt, a professor at UC Santa Cruz who developed some of the instruments Butler and Marcy use in their research. "That's an inspiration to a lot of people who find their careers taking them from world-class research to being at a small teaching college."

Marcy decided to dedicate his life to planet-searching 12 years ago, when the slow pace of his postdoctoral research on stellar electromagnetic waves threw him into a listless, inferiority-sodden funk. The way he saw it, he could either spend the rest of his life languishing in astronomy's abstract realms, or turn his research toward the sort of questions that attract people to gaze at the night sky in the first place: Are we alone? Is our solar system unique?

Butler came aboard three years later while working on his bachelor's degree in chemistry at S.F. State. Marcy had just become a junior faculty member, and he told the promising young scientist that he knew of a way they might be able to find planets.

The field of searching for extrasolar planets had been scorned by other astronomers, in part because it was fraught with failures.

"This field is littered with the bodies of people who made claims of one thing or another -- claims that have fallen by the wayside, claims where they didn't really see the effect they said they did, or where they were seeing something else entirely," says David Black, director of the Lunar and Planetary Institute in Houston.

One of the most notorious such failures was Peter van de Kamp, a former director of Swarthmore College's observatory who went to his grave believing he had detected a planet-induced wobble in Barnard's Star, the third closest to our sun. Other astronomers concluded he hadn't noticed subtle changes in his telescope, perhaps caused by the removal and replacement of lenses.

Earlier attempts at finding planets tried to measure stars' gradual wobble from side to side by watching them directly through a telescope over long periods of time. Repeatedly, however, this type of research had been tripped up by telescopic distortions involved in making such fine, long-term measurements.

The trick, Marcy and Butler decided, was to devise a technique immune to such perturbations.

Planet-searchers had long believed that the apparent side-to-side wobbles of some stars were evidence of the gravitational pull of orbiting planets. A star pulled around by an orbiting planet would move in a tiny circle, just as our sun does. Marcy and Butler decided they might avoid some technical pitfalls if they looked for the portion of that circle during which the star appears to move toward, then away from, Earth, instead of side to side.

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