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

Superstars of the Universe
Paul Butler leans his gangling 6-foot-2 frame into a tiny office chair, sweeps the back of his hand toward the fuzzy ball of light on a nearby video screen, and erupts: "That star's booooooring. That's 70 Virginis, which has a massive, eccentric planet. That's a completely booooring system. We know its period, we know its orbit, we know everything about it. I only keep observing it to keep gathering data points, but for all intents and purposes, we've nailed it.

"It's downright boring. Boooooring."
Butler is spending a good-natured -- no, downright ebullient -- night at the bathroom-size, computer-filled observation room of Lick Observatory near San Jose. Just as he has done for hundreds of nights during the past decade, he is scanning the skies for evidence of planets, an activity that recently made him and his research partner, Geoff Marcy, two of the most famous scientists in (this) world.

Using exquisitely subtle, indirect methods to look at the skies, Butler, a UCBerkeley research fellow, and Marcy, an S.F. State professor, have calculated during the past 18 months that there are planets circling a half-dozen stars that are, in astrophysical terms, near to Earth. The scientists will soon announce at least six more, and during the next few years they expect to have discovered more than 100 planetary systems.

For all the science-fiction novels, UFO conventions, and Star Trek episodes that might indicate otherwise, these discoveries mark the best scientific evidence that Earth-like planets exist outside our solar system. This fact has made Butler and Marcy heroes in several earthly realms.

Bureaucrats at NASA -- who hope the search for life in outer space will inspire the imaginations of taxpayers like the race to the moon once did -- revere them.

Astrophysical theorists -- who had long been stuck explaining the cosmos without any sun-and-planets solar system but our own to go on -- cherish them. "Poor theorists had been suffering a lack of data," laments Joseph Burns, editor of Icarus, a scientific journal dedicated to solar system studies. "Now we have some data, and it's great fun."

But it is journalists who have appreciated Butler and Marcy most of all. After awkward careers spent dumbing down the science of quasars, explaining gravitational warps in far-off nebulae, and describing minuscule modifications of the big-bang theory, science writers finally found in Butler and Marcy a story that cut to the chase: There are planets out there, and earthlings have seen them.

What followed has been the scientific equivalent of rock superstardom. The Marcy-Butler story has graced the covers of Time, the Washington Post, and the New York Times. They've been featured on The Today Show, Nightline, and the BBC's Breakfast Show. They've given speeches all over the world, and Butler, who earned two bachelor's degrees and a master's at San Francisco State University before getting his Ph.D. in Maryland, last year joined Willie Brown in SFSU's pantheon of alumni of the year.

"Over there, that's where the Time photographer shot us. On this side is where the Washington Post guy had us," says Butler, as he bounds up the stairs leading to a catwalk that rings Lick's grain silo of a telescope. "The Los Angeles Times wanted to send someone over to interview us this week, but I had to tell them we just didn't have time."

The Zone
But there is disquiet in this glory.
For all their fame, for all the accolades, speaking tours, and television appearances, Butler and Marcy now occupy some of science's most miserable temporal terrain. They are living in the delay that exists between the moment major scientific discoveries are first made, and the time they are duplicated -- or debunked -- by their peers.

It is during this period that a scientist may become a hero, a star, a Johannes Kepler -- who wrote the mathematical laws governing how planets orbit our sun. Or a researcher can become a goat, a loser, a Martin Fleischmann -- whose 1989 claim to have produced cold nuclear fusion was later discredited.

It is during these periods of confirmation or disproof that scientific revolutions fail or succeed. This is when humanity makes its herky-jerky progress from old ways of understanding nature to new ones. Just the same, it's a trying time for everybody concerned -- the discoverers, their challengers, and the rooters on the sidelines.

As Butler and Marcy await the papal white smoke of peer confirmation, challenges to their work arrive thick and fast. And the challengers have credentials.

Where once Butler and Marcy spent time with reporters speculating about the type of life that might exist on their extrasolar planets, the scientists now bitterly impugn the editorial standards of journals that publish the work of rivals -- rivals who say Butler and Marcy have misinterpreted data and posited planets where none exist. Mention the work of these rival astronomers to Butler or Marcy, and their ordinarily bright, agreeable demeanors turn a shade darker. The friendly loquaciousness subsides. They speak in irritated, condescending tones.

"More than anything, I'm worried about his career," Marcy says, after an hour of ravaging the work of a Canadian professor who believes the planets "discovered" by the Butler-Marcy team may not exist. "I really am. I'm worried about him."

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.

Astronomers have a technique for detecting how fast stars are receding from or approaching the Earth. That method involves what is known as the Doppler effect, a phenomenon first described by 19th-century Austrian scientist Christian Doppler.

When the source of a sound moves toward, then away from a person, the pitch of the sound seems to change because of the perceived compression, then stretching of sound waves. (The change in pitch of the sound of a freight train passing is the commonly used example.)

The kinds of changes that occur when a speeding object creates sound waves also occur with light, which has some wave characteristics. When a star moves toward the Earth, the light it emits appears to be shifted slightly toward the blue end of the visible light spectrum. When a star recedes, its light shifts to appear toward the low -- or red -- end of that spectrum. A jiggling telescope may create phantom changes in a star's position, but not its color, the reasoning went.

To search for this effect, Marcy and Butler decided to tease stars' light through a spectrograph -- an astronomer's high-tech prism. The prism casts starlight in rows of "spectral lines" on an electronic plate linked to a computer. If those lines move from blue to red, the San Francisco astronomers figured, they could prove a star is wobbling -- perhaps as a result of the gravitational tug of a planet orbiting nearby.

When Marcy and Butler first decided to use this type of planet search 10 years ago, even the highly sophisticated Doppler technique was too crude to positively detect the subtle nudging effect planets have on stars.

Nearly anything -- the expansion and contraction of a spectrograph's metal and glass with the changing of seasons, the sagging of the spectrograph under its own weight -- can distort spectral lines and fool an astronomer looking for such subtle effects in light from stars that are light-years distant from Earth.

"It's like taking a wooden ruler and trying to measure to within a billionth of an inch of accuracy," says Steve Vogt, the UC Santa Cruz astronomer who designed the powerful Hamilton Spectrograph through which Butler and Marcy made their observations at Lick Observatory. "If you stand the ruler on its edge, it will become shorter because of the weight of the ruler. You can't pick up the ruler -- the heat from your hand will expand it.

"We need an accuracy of one part in 100 million to see these planets. It's a horrendous calibration problem."

It was a problem that astrophysics -- the blending of astronomical observations with laboratory physics -- had been unable to solve. But a third science changed the planet-finding equation, thanks to Butler's chemistry degree.

Butler knew that the element iodine, like all matter, casts an unchanging, signature "shadow" when light is shined through its gas form. On Butler and Marcy's spectrograph, the shadows are cast in the form of a series of tiny, rulerlike lines.

Previously, astronomers had included guesswork calculations in their research to account for the shifting, shrinking, distorting effects created by changes in their spectrographs. But Marcy and Butler were able to measure the constant they were searching for -- the rocking back and forth of distant stars -- against another constant: the immutable telltale lines cast by illuminated iodine gas.

While it seems self-evident now, Butler had to spend a year puttering in a chemical lab to come up with their iodine measuring stick. Now, even competitors say the trademark blown-glass iodine cell that Butler and Marcy cast their starlight through makes the San Francisco astronomers' observing techniques the most precise in the world. NASA's planet-search program recently paid Marcy and Butler $200,000 for a version of the cell, which cost only $400 to build.

But for all the technical wizardry involved in this type of search, peers credit the success of Butler and Marcy to the dogged determination that led them to spend thousands of hours in chemistry labs, university computer rooms, and telescope observation rooms. That their peers saw them as the scientific equivalent of UFO buffs didn't make things easier.

"You'd go to the dining room for dinner, and other astronomers would say, 'We're looking for high red-shift galaxies,' and we'd say, 'We're looking for planets,' and they'd sort of look back at their food," says Chris McCarthy, a UCLA doctoral candidate who did graduate work with Butler and Marcy at S.F. State. "At the time, that was only slightly better than the people looking for signals from life in outer space."

Butler recalls reading a planet-search paper at one conference where attendees literally laughed out loud at him.

"I'd been laughed at, but it didn't bother me because I knew I was right, and I was quite sure that if I continued on this track, I would be shown to be right. And in fact that I would win the race. So yeah, we stuck our neck out quite a lot, but we were fairly confident.

"It's not that we were so smart. There are a lot of people out there smarter than us. But we don't like to lose. We are quite confident that we will do what it takes to win."

Butler and Marcy hit pay dirt at 8:30 a.m. on Jan. 17, 1996, at the annual meeting of the American Astronomical Society at San Antonio's El Palacio del Rio hotel. The society had arranged a press conference to present papers from the conference. Marcy dropped a bombshell, announcing two newly discovered planets. One was found orbiting the star 70 Virginis in the constellation Virgo; the other circled 47 Ursae Majoris, in the Big Dipper.

Weeks before, Swiss astronomers Michel Mayor and Didier Queloz had announced they had used similar techniques to detect a planet orbiting 51 Pegasi, in the constellation Pegasus. Marcy and Butler had also been observing 51 Pegasi, and they warmed the audience up in San Antonio by announcing they had confirmed the Swiss astronomers' results. But the response to the San Antonio announcement was bedlam, just the same. One of the Marcy-Butler planets appeared to be temperate enough for liquid water to exist there -- in other words, the life zone was present somewhere else in the universe.

"Bring your fishing rods, because there's water," Nature Astronomy Editor Leslie Sage recalls Marcy saying.

After a decade in the cold, after 10 years in featureless office cubicles, cramped observing rooms, and neon-lit college chemistry labs, Marcy and Butler were invited into the warmth of mainstream astronomy. And they became really, really famous.

Marcy and Butler have a Web page called Planet Search. Linked to it is Butler's electronic resume, which mentions 48 newspaper, magazine, and television stories under the heading "Selected Recent Media Coverage & Public Outreach." The articles indeed represent a small sampling of the hundreds of articles published around the time of their San Antonio announcement.

The Gray Letter
Not mentioned on Butler's curriculum vitae are the dozen or so articles in publications such as New Scientist, Astronomy, and Scientific American spawned by an event remembered in astronomical circles as "The Gray Letter."

The news stories described a brief article -- it took up just two pages -- in the Feb. 27 issue of Nature. The article, written by University of Western Ontario astronomer David Gray, was graced with the boring title "Absence of a planetary signature in the spectra of the star 51 Pegasi."

But a piece of commentary in the front of that same issue of Nature grabbed the attention of journalists and astronomers with this headline: "One of our planets is missing."

In his Nature article, Gray said that he, just like the Swiss astronomers Mayor and Queloz, and just like Butler and Marcy, had looked at spectral lines created by light from 51 Pegasi through his own telescope in Ontario.

Gray used a different method of measuring changes in the spectrums of light from the star. Using that method, Gray said, he detected the telltale sign of a star that is swelling and then contracting, rather than moving back and forth under the influence of planetary gravity. In other words, Gray maintained, the star was vibrating to the rhythm of its own nuclear fires.

Marcy and Butler were quick to respond, drafting a one-page paper calling the Ontario scientist's assertions nonsense. The paper, posted to their Website, contends that Gray's theory proposes an impossible sort of star -- one that would shrink to half its size, then swell back again to original volume, every four days or so.

For Gray, however, the San Francisco astronomers' rush to rebut merely betrayed how jealously they guard their coterie of planets.

"If one gets emotionally attached to a particular hypothesis, one is going to get upset," Gray says.

Gray wasn't the last scientist to lance at the theory of planets in outer space. As has been the case with scientific discoveries through the ages, challenges are beginning to mount. The resulting zone of doubt has been at least as cruel to the challengers as the challenged.

Attack of the Binary Stars
Xiaopei Pan, a polite man in slacks, a white shirt, and black canvas slip-on shoes, gestures at the left wall of his small office in the basement of the astronomy building on the campus of the California Institute of Technology in Pasadena. On that wall are copies of papers he has written, a citation he received in a book about U.S.-funded astronomical research, graphs describing stars he has observed.

They're mementos of a 17-year sojourn that led from life as a government scientist in the People's Republic of China to the vanguard of U.S. astrophysical research.

Now, like Butler and Marcy, Pan sits in an extremely uncomfortable zone of uncertainty.

He wishes to publish a scientific paper that would, if true, erase at least two of the newly discovered extrasolar planets: 51 Pegasi, the first ever discovered, and tau Bootis, a similar system, found by Butler and Marcy, that appears during the summer to observers in the Northern Hemisphere. But to publish, he will have to defy his department, other members of his research team, and the customs of U.S. science.

His anguish is palpable.
"We're all looking for the truth," Pan says. "This research is funded by taxpayers. We're supposed to tell taxpayers the truth."

Pan left his job as a Chinese government astronomer 17 years ago for a stint as a visiting scientist at the U.S. Naval Observatory and the freedom of Western-style science.

A scientific prodigy, Pan achieved a high position as a mainland China government scientist after graduating from the department of astronomy at Nadjing University in 1967, and later receiving his doctorate from Academy Sinica in Taiwan.

But he was intrigued by the careers of the Western scientists he met when he traveled to conferences -- the raucous hubbub of competing theories, the state-of-the-art research on multimillion-dollar instruments. In 1980, he was courted by the U.S. Naval Observatory and took a two-year appointment as a visiting scientist there. When offered an appointment at the Harvard-Smithsonian Center for Astrophysics in 1987, he grabbed it. And when Harvard scientists Mike Shao and Mark Colavita jumped to the West Coast to work on the next generation of interferometers -- arrays of individual telescopes whose images are combined -- Pan followed suit.

He would be joining an astronomical dream team that would operate in dream conditions. Working on Mount Palomar outside Los Angeles, in partnership with NASA's Jet Propulsion Laboratory, these scientists would develop the most advanced instrument of its kind. Under the direction of Caltech Professor Shri Kulkarni, Shao and Colavita would perfect the NASA interferometer, which delicately combines the light from several telescopes in order to detect objects no other instrument has. Pan would conduct astrophysical research on the instrument.

If all went as planned, the Caltech-JPL team would eventually move from Mount Palomar to Hawaii, where the researchers would turn the Keck astronomical observatory's apartment-size, 10-meter telescopes into a pair of combined-image binoculars. Thereafter, the team would spearhead NASA plans to send a binocular telescope into space at a cost some say could reach $10 billion.

The mission of this NASA-funded research program was almost Star Trekian in its ambitions: These men were to find planets -- and perhaps, the conditions for life -- in star systems far from our own.

But the dream team has faltered in its trajectory because Xiaopei Pan's research went where no NASA-funded scientists had gone before: The results, he believes, show that in at least some cases, Butler and Marcy have been wrong, and found planets when they should have found stars.

Other members of Pan's team disagree. Shri Kulkarni, the leader of Pan's research team, says Pan based his conclusions on observations made before the Mount Palomar interferometer was perfected, and before the team could make reliable scientific interpretations based on its data. Shao and Colavita say the same thing.

"If you want to go out on a limb, you could say it is resolved -- which wouldn't be wise," says Kulkarni of Pan's assertion. "It takes a couple of years to debug these systems. Most of us in the group don't think we can say anything about whether 51 Pegasi has a companion star."

A companion star, instead of a planet.
Pan, a specialist in the science of binary, or double, stars, likes to remind people that lone stars like our own sun are a minority in the universe. Most stars are paired with companions; these dual stars spin around in space, like the tips of a propeller blade, in eons-long dances. Some 70 percent of the stars in the universe are joined in this manner, akin to the double suns that hovered over Luke Skywalker's home in the movie Star Wars.

"The heavens are like a human society," says Pan. "Couples are common, singles are rare."

Pan believes at least two of the stars Butler and Marcy say have planets are actually being tugged around by binary companion stars. Using the experimental interferometer telescopes atop Mount Palomar, Pan has been observing the stars 51 Pegasi and tau Bootis over the course of nearly a year, and he believes he has enough evidence to submit a paper to Nature this month that would erase two of Butler and Marcy's planets from the sky.

If Pan's assertion were true, it would explain everything. It would account for Gray's stellar pulsations, the wobbles of Marcy and Butler -- everything. As they spin around in lock step, the competing gravity of binary stars can cause one another's mass of nuclear plasma to billow and slosh in a way similar to how David Gray says 51 Pegasi does. As for the wobbling back and forth that Marcy and Butler observed: Binary stars pull each other around in one of the most dramatic gravitational dances in the known universe.

Pan believes so strongly in his results that he plans to submit his paper to Nature in defiance of the other members of his research team. This is a highly unusual move. Until now, papers he has produced using the Palomar interferometer have also borne the names of Kulkarni, Colavita, and Shao.

Already, Kulkarni, Colavita, and Shao have gone into an astronomer's version of spin mode, working to stem the public relations disaster of NASA-funded astronomers bickering in public.

"We've now decided to have one spokesman at Caltech, which is me, one at the Jet Propulsion Laboratory, which is Mark," says Kulkarni, warming to the task of public relations flack. "At the end of this conversation, you will realize that I haven't told you anything at all."

It is far too early to tell whether there is any substance to Pan's claims that some of the Marcy-Butler planets should be erased. Given that his own research partners challenge his results, he will be hard pressed to win over the jury of independent scholars that Nature uses to judge whether papers should be published.

But Pan says his partners' assertion that the Palomar interferometer is too primitive for reliable research is specious on its face. Pan has published papers describing other binary star systems he has observed with the Palomar instrument -- without raising anyone's hackles.

"You see this? This is a binary star," Pan says, holding a paper with graphs, waves, and plots on it. "I see other binary star, and no one minds. It's not controversial.

"I make a planet disappear, and everyone gets angry."
Pan's claims have not drawn unanimous scientific scorn.
Wesley Traub, a physicist at the Smithsonian Astrophysical Observatory, works on an array of interferometer telescopes in Arizona; they are designed to look at infrared light emitted from stars. Traub worked with Pan at the Harvard Smithsonian Center for Astrophysics and is familiar with work done on the Palomar interferometer. While he can't specifically vouch for Pan's claim to have found binary companions to the famed planet stars, he's taking the results seriously enough to do his own observations on those stars.

"Pan has measured quite a number of binary stars very accurately and beautifully, and I have the highest regard for his experimental technique," says Traub. "You can be absolutely sure we will look at it, and other people will.

"Because if true, it's a really amazing discovery."

Interplanetary Heroine
When you first meet Sallie Baliunas, she strikes you as the kind of woman who, if only she were a few years older, might have been a close friend of Bill Clinton's mother. With her matching lime-green sandals and pantsuit, tousled red hair, and easy, gregarious manner, you can imagine meeting Baliunas at a county fair, or a hot-rod auto show. In one way, you wouldn't be far off the mark: She's the owner of a tricked-out '34 Ford three-window coupe, a '70 Corvette, and a '57 Chevy Bel Aire.

In all the other ways, however, you would have missed the target by light-years. Make no mistake about it, unlikely as it may seem, Baliunas is a hero to the cause of science.

She's wanted to be an astronomer since she was 6 years old, when an Air Force recruiter told her little girls couldn't grow up to be astronauts. Her relentlessness has helped her become one of the world's most accomplished astronomers, a much-sought-after expert on sun spots and the magnetic fields of stars. She spends her time jetting between the Mount Wilson Observatory near Pasadena, where she is deputy director of the Mount Wilson Institute, and Cambridge, Mass., where she is senior astrophysicist at the Harvard Smithsonian Center for Astrophysics. She has been a co-researcher at different times with Marcy, Butler, Gray, and countless other prominent researchers.

These seemingly disparate elements of her character -- the approachable everywoman and the jet-setting astrophysicist -- have made her an ideal diplomat in the zone of doubt surrounding extrasolar planets.

She hopes to corral a group of bickering rival scientists from around the continent and have them collaborate on a joint paper in July. That paper will attempt to prove or disprove David Gray's claim that distant stars billow like bullfrogs, and confirm or cast aside a major claim that the San Francisco planets are ephemeral. Thanks to Baliunas' efforts, the controversy surrounding the Marcy-Butler planets may be one of the shorter-lived in scientific history.

"It occurred to me that perhaps I can play Solomon in this case," Baliunas says. "There was this dispute between what Gray and Marcy and saw, so I sent an e-mail to everybody and said, 'Why don't we take our measurements in unison?' "

By coordinating the research of teams at sites including the University of Texas, Harvard, the University of Western Ontario, and S.F. State, Baliunas' paper will force a choice between the two visions of outer space implied by the work of Marcy, Butler, and Gray -- all of whom say they will contribute to Baliunas' paper.

The first vision imagines millions of solar systems with planets, some of which harbor life; the second, a universe filled with previously unimagined billowing stars that pulse as dramatically as a frog's gullet.

The scientists will first focus on the star tau Bootis, in the constellation Bootes. Fifty-one Pegasi, the original planet-bearing star which Gray says appears to be swelling and contracting, rather than wobbling, won't be visible to the powerful telescopes that scan the northern skies until this fall.

The planets that supposedly orbit tau Bootis and 51 Pegasi would be extremely strange by the standards of our solar system.

The planet envisioned as orbiting 51 Pegasi is relatively large -- half the size of Jupiter -- and searingly close to its star, about one-twentieth the distance between the Earth and the sun. The planet would have a surface temperature of 1,300 degrees Celsius -- about the temperature at which astronomers previously believed planets would boil away. Odder still, the planet appears to spin around its sun once every 4.2 days. Tau Bootis' planet is believed to behave in a similarly dizzy fashion. (The Earth, of course, circles the sun once every year.)

Scientists are already searching for subtle changes in tau Bootis' spectral lines. Baliunas' astronomers hope to determine whether the star is moving back and forth, or swelling and shrinking. The various teams will tally their results this month, and meet July 17 to draft a paper asserting that there is, or is not, a planet out there.

In the meantime, the two sides are indulging in pre-showdown posturing.
Gray "was in a funny mood when he wrote his paper. I'm going to try to avoid amateur psychology here. But he was in a mood where he thought he had a 'gotcha' -- we all have had moments like that in our lives -- and there is no question in my mind that he wrote this as a gotcha paper," says Marcy of his Canadian colleague.

Gray counters by saying that planet-searching "seems to be an area that inspires the popular imagination, and I think some of these scientists have been swept up in that. You're seeing some slightly aberrant behavior."

The Passion
Gray's criticism fails to acknowledge a clear reality: Aberrant behavior is required to produce cutting-edge science.

Talk to Xiaopei Pan long enough, and he'll describe spending the Christmas and New Year's holidays in the cold of the Mount Palomar interferometer. He'll mention taking his family halfway around the world to get a better look at faint, faraway stars. He'll cackle at the thought of "erasing" planets.

After about an hour of conversation, Paul Butler will describe the 40-minute John Coltrane saxophone solo he sometimes plays on his stereo for his friends, to test them, to see if they understand the excitement of hearing someone chart new territory in his chosen field.

He'll tenderly, admiringly describe his ex-wife, then segue into an explanation of why the demands of his planet-searching weren't compatible with the kind of life she wanted to lead. He'll note that he is moving to Sydney in September to search for planets on a telescope there and lament that the move will probably mean he'll have to break up with his girlfriend.

"It's kind of hard to have any sort of settled or stable personal or home life," says Butler of his quest to be the first to identify planets around Southern Hemisphere stars. "But it's very simple. The southern stars haven't been done. Other big telescopes are coming on-line in the south now, but it'll be two or three years before they can make observations, and there is a perfectly wonderful facility in Australia that can do it right now."

"I just physically cannot bring myself to wait three more years to get started. I'm just going to go wherever I can go right now to get these stars under survey."

Butler exudes the same sort of passion that consumes an Olympic athlete, or an avant-garde musician: irrational, traumatic, irresistible. It's a passion that makes this zone of doubt so painful and contentious. But that passion is perhaps the main reason science has advanced through the 20th century like a meteor: Scientists have sat up nights, crazy to become the first to know.

And when someone says they might not be first, that they might be wrong, it is upsetting. Michel Mayor, the Swiss scientist who discovered 51 Pegasi's planetary wobble, recalls feeling horrified when he first learned of David Gray's paper -- the one that may erase his planet.

"You are disturbed, your brain is working rapidly," says Mayor. "After this short period of emotional reaction, we say, 'We have to be quiet, we have to be cool. We have to think about what the facts are.' "

Essential facts surrounding Butler and Marcy's mysterious stars are almost within reach.

Results are already beginning to come in for Baliunas' paper. A Harvard group working in Arizona released calculations in June that they believe lend credence to the theory that 51 Pegasi and tau Bootis indeed host planets.

"We'll definitely be including their results as part of our paper," Baliunas says.

Scientists also expect to quickly resolve the mystery surrounding Xiaopei Pan's challenge.

Shri Kulkarni says modifications made during the past few months to the Mount Palomar interferometer telescopes have significantly increased their precision. The Caltech-JPL team plans to train the newly refined instrument on the supposedly planet-bearing stars and make a more reliable determination about whether or not the Butler-Marcy planets are real.

"We will be able to say something in a few months," Kulkarni says.
If the new research makes some of the planets disappear, Marcy, Butler, NASA (which is basing an ever-greater portion of its funding appeals on the quest for life in outer space), and starry-eyed science writers will be deeply disappointed.

So will the many astrophysical theorists who, delighted by Marcy and Butler's discoveries, have fashioned a slew of new theories to describe a universe of huge, superhot, fast-orbiting planets.

"At first I was amazed: If you have a Jupiter-sized planet so close to the sun ... how could it hang on to its atmosphere if it was that hot?" says Mary Barsony an astrophysicist at UC Riverside. "But then we did a back-of-the-envelope calculation. ... We figured out that it really can hold on to its atmosphere."

Theorists will have to start over again if those planets are shown not to exist.

The Bay Area media, which a year ago made Butler and Marcy heroes, have heaped the scientists' challengers with journalism's sincerest form of scorn: They have ignored them.

The journalists shouldn't be so cruel.
Even if all of Marcy and Butler's challengers are correct, and some of their planets disappear, the two San Francisco scientists don't stand to be humiliated the way planet-searchers have in decades past.

Even rivals agree that the measurements taken by Butler and Marcy are exquisite. It is only the interpretation of those measurements that is open to question. And, astronomers agree, it's not likely the Butler-Marcy interpretation will be proved completely wrong.

Even if Gray's theory proves correct, and the supposed planets orbiting 51 Pegasi and tau Bootis prove ephemeral, astronomers say that the existence of other planets will, for now, remain unchallenged.

Several of the wobbling stars discovered by the San Francisco astronomers have long cycles -- 84 days, 116 days, 1,103 days -- a phenomenon that even Gray admits could not be caused by the type of sloshing oscillations he describes for 51 Pegasi and tau Bootis. A planet is the only currently known explanation for those long-period wobbling stars, Gray acknowledges.

Xiaopei Pan says he doesn't expect to erase all of Butler and Marcy's planets, either. The existence of planets is a perfectly logical explanation for wobbling stars -- except when measurements detect a binary stellar companion instead, he says. Pan envisions a day when he and the San Francisco scientists cooperate closely, using their distinct methods to make irrefutable observations of far-off planets. In some cases they'll find planets, in some cases, other phenomena.

Together, Pan envisions, their results will help create a more complete picture of the universe. Didier Queloz, one of the Swiss planet-searchers, agrees. He plans to spend time working with Michael Shao at the JPL next year, says Mayor, Queloz's research partner.

By that time, the zone of doubt surrounding extrasolar planetary research will have neared its end, and astronomers worldwide will have gone back to conducting what historians call "normal science." They'll then do incremental -- instead of revolutionary -- research, perhaps using methods developed by Marcy, Butler, Pan, Kulkarni, and Gray.

And in a decade or so, high school science texts may tell children how many planets science believes exist in the universe. Textbooks may tell them about the Bay Area researchers who developed the revolutionary techniques that made high-precision planet-searching possible. And they may describe those scientists' challengers, who showed that perhaps not everything that appears to be a planet, is.

This is the zigzag course science has traversed through the centuries, bringing humanity ever closer to understanding the universe.

To be sure, not every zig in the process is to the liking of every scientist.

"This David Gray stuff for me is boring. It's just not happening," says Butler, taking a short break at the UC Berkeley workstation where he has spent the day poring over lists of stars, choosing which ones he'll view next.

"It's boooring.

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