Planet Search at 67 and Counting

Night after night, as his parents slept, Geoff Marcy clambered out of his bedroom window and onto his San Fernando Valley rooftop to gaze at Saturn’s shifting moons through a used 4 1/4-inch telescope. He was 14 and he was obsessed.

As he peered into the skies over Granada Hills in the late 1960s, he was driven by the age-old questions that animated the science fiction he devoured: Were there other planets out there, beyond the nine circling our own sun? Were there other Earths teeming with life? Marcy was certain there were.

His instincts would take him on a lonely, 30-year odyssey from a $50 rooftop telescope to the world’s most powerful astronomical machines as he struggled to tease out the slow, telltale wobbles of stars dancing with planets some 200 light-years from Earth.

Marcy, now 46, has become the world’s most successful planet hunter. Not only has he found more planets than anyone else, he also has discovered a systematic, almost easy way to find them. In doing so, he has conferred legitimacy on a field of inquiry once regarded by his colleagues as a crackpot pursuit, because planets beyond our solar system couldn’t be seen even with the brawniest of telescopes.

Thanks to the techniques he and a partner pioneered, 67 extrasolar planets have been discovered so far, with dozens more “maybes” under scrutiny.

“We’ve got planetary systems coming out of our ears,” Marcy said after a recent all-night planet hunting session in Hawaii at the world’s largest optical telescope, the Keck. “Planet hunting has morphed from the magnificent to the mundane.”

Today, the boy who found inspiration in the made-up worlds of science fiction is celebrated as a Marco Polo of contemporary astronomy. But before he began conjuring new planets out of the darkness of deep space, Marcy had to learn what it was like to be invisible himself, to spend decades laboring on the margins of acceptability, scoffed at by the scientists he had admired for years.

“They wanted to know if I was going to discover pyramid power while I was at it,” Marcy said. “It was a little too close to little green men and ESP.”

The search for new planets has consumed the lives of astronomers since the time of the ancient Greeks. An Italian monk, Giordano Bruno, was burned at the stake in 1600 for suggesting the presence of “countless Earths.”

Since then, the field of planet hunting had been thoroughly discredited by a succession of bogus claims. Even with the most powerful modern telescopes, most scientists thought detecting planets was impossible. Seeking distant worlds was not anything to pin a career on. Marcy’s dream was the stuff of TV fantasy, a “Star Trek” script.

As he worked his way toward a summa cum laude degree at UCLA and a PhD in astrophysics at UC Santa Cruz, Marcy never stopped asking questions about the distant worlds that had intrigued him as a boy. But he did stop asking them out loud.

Instead, as a graduate student, he turned to a more academically acceptable pursuit. He sought to find out if other stars had strong magnetic fields like the one around our sun that causes auroras, sunspots and flares. The answer could reveal much about the inner workings of stars.

Though he didn’t know it at the time, his struggle to make the minuscule measurements of magnetic fields was ideal training for trying to discern the existence of invisible, extrasolar planets.

After toiling for five years, Marcy claimed to have found the magnetic fields. But many scientists were unconvinced. One Harvard astronomer dismissed his findings entirely. Although the work earned him a two-year fellowship at the Carnegie Observatories in 1982, Marcy was despondent.

“I was feeling so bad about my abilities as a scientist,” he recalled, “I wondered if I was edging toward being suicidal.” One talented colleague did take his own life. Another dropped out of the graduate program.

Depressed as he was, Marcy didn’t quit. Instead, his anguish carried him back to the search that had preoccupied him as a child. His breakthrough came in the shower. It all became clear. He should start looking for planets.

“I was standing there, with water running down my back, thinking I can’t go on like this,” he said. “I didn’t have anything to lose. If I was going to be gripped with angst, at least I was going to do something so monumental, it was going to be worth it even if it failed.”

Beyond the Boundaries of Safe Research Topics

Marcy was headed toward an academic frontier, beyond the boundaries of safe, sanctioned research topics, a place where jobs and grant money were scarce. He would spend the next 14 years at San Francisco State University, an institution where teaching comes first and research is often an afterthought. Only his nights were free for planet hunting.

He began working long past midnight, a practice he continues to this day. He had only a shoestring budget and a handful of aging computers that he repaired himself with soldering irons.

Colleagues at research universities told Marcy that he didn’t stand a chance of finding planets. The problem is that planets are impossible to see from great distances. They don’t produce their own light. Planets do reflect light from the stars they orbit, but that light is lost in the glare of those stars, just as the glow of a firefly is lost when it flies in front of a searchlight.

But Marcy wasn’t expecting to see new planets through the eyepiece of a telescope. He was relying as much on computers as on telescopes. His approach was unromantic, and decidedly 21st century.

“Ninety-nine percent of the time, we sit in front of our computers writing software, running software and analyzing software,” Marcy said.

For 100 years astronomers have known the best hope of finding planets was by detecting their effects on nearby stars that can be seen through a telescope. A planet, even a small one like Mercury, exerts a tiny gravitational pull on its star. As the planet orbits the star, it literally tugs the star around, causing it to wobble.

Determining the existence of a distant planet, one you cannot see, is rather like inferring the existence of wind from the movement of a branch.

But such movement can have other causes. A wobbling star might be reacting to the gravitational pull of a nearby planet. Or, the wobble might be caused by the frothy foaming of an active star’s surface or the result of an internal “starquake.”

Many failed planet hunters have confused one cause for another, or simply forgotten to make a single correction in a long series of calculations.

Missteps are hard to avoid given the maddeningly tiny, almost imperceptible shifts in starlight that signal a clear wobble.

Measuring that wobble, astronomers say, is like trying to determine the amount a ruler shrinks from the pull of gravity when stood on end.

Most astronomers have been satisfied when they have been able to detect objects in deep space moving at speeds of 2,000 mph. The movements Marcy was trying to measure were less than 20 mph, or 10 meters per second.

Marcy didn’t bring any conceptual breakthrough to the process. He just brought a dogged determination to find a way to make the measurements that had eluded others--and to keep pushing until he did so.

“I constantly asked the question, ‘Why not? Why can’t we do this?’ ” he said.

Marcy discovered that a Canadian astronomer, Bruce Campbell, had devised a way to make more precise measurements by comparing starlight to a stable artificial atmosphere.

Campbell filled a glass bottle with luminescent gas and placed it inside the telescope. But he used hydrogen fluoride, a corrosive, explosive gas that was fatal to the touch. And the measurements--down to 12 or 13 meters per second--still weren’t precise enough.

Campbell, disillusioned by the difficulties of planet hunting, eventually left science. He now runs a candy store.

Marcy began looking for another chemical. In 1986 he started collaborating with Paul Butler, a graduate student and chemist at San Francisco State who yearned to return to his first love, astronomy.

Five years younger than Marcy, Butler had grown up in Los Angeles too. The son of a city police sergeant, he became captivated by space after the 1969 moon landing. From then on, he spent much of his youth searching the skies with an 8-inch telescope he built himself. He explored the heavens from a backyard in Simi Valley.

Different Styles Working Together

Though they would eventually work in lock step, Butler and Marcy could not have been more different. Butler, whose taste tends to untucked polo shirts and baggy jeans, looked every inch the scientist or computer wizard.

Among his heroes, he counted Bruno, the Italian monk executed for his astronomical heresy. Marcy, who favors black clothes, collarless shirts and a neatly trimmed goatee, would look at home in a Hollywood production meeting. In discussion, he is more likely to mention Freud than Copernicus.

Marcy was the analytical, theoretical one. He worked out strategies in his head.

Butler figured out how to get them done. “We wouldn’t get anywhere if it wasn’t for Paul,” Marcy said. “He gets his fingernails dirty.”

The Search Included Physical Risks

It was Butler who found the chemical they needed to measure the tiny fluctuations of starlight. He tinkered with thiophosgene, a cousin of mustard gas--fatal even in faint concentrations--and chlorine dioxide, which explodes in the presence of sunlight. He worked overnight to reduce the chance of injuring anyone if the chemicals exploded. In the end, he found that iodine, a relatively harmless chemical, provided the cleanest measurements.

Still, Marcy and Butler couldn’t find planets. The telltale wobbles continued to elude them. They needed even more precision.

Marcy turned to his old advisor at Santa Cruz, Steve Vogt, a rare breed of astronomer who designs astronomical instruments from scratch. To look for wobbling stars, Marcy and Butler were using the Lick, a 50-year-old telescope perched above San Jose.

Vogt had built an instrument on the telescope, the Hamilton spectrometer, that carefully split light into its different components like a prism. The powerful instrument could divide light into tens of thousands of wavelengths.

Starlight gives a clue to how a star is moving because it changes slightly depending on whether the body is moving toward or away from the viewer. This phenomenon is called the Doppler effect.

When Vogt heard the team needed more precision to measure the effect, he carefully rebuilt the spectrometer so that shifts in light colors caused by the movements of a star would stand out more clearly.

To detect the orderly movement of a star being orbited by a planet, the team still had to determine exactly what those changes in light meant. They had to analyze each component of light separately. Then they had to correct for a multitude of factors: the speed of the Earth’s rotation, the effect of the moon, the position of the telescope on Earth. The work required six years of programming by Butler. He calls the end product “my Rembrandt.”

By 1995, the invisible world was finally within their grasp. At last, they could study stars 200 light-years away and detect movements as slow as 3 meters per second. “Walking speed,” said Vogt. Slow enough to detect planets the size of Jupiter. If there were hidden planets out there, Marcy and Butler would now be able to find them.

“We were stunned at the precision,” said Marcy. “It meant we couldn’t lose.”

Beaten by Another Team

On Oct. 6, 1995, Marcy and Butler were unexpectedly beaten.

A Swiss team--Michel Mayor and Didier Queloz--found the first extrasolar planet. It was a fluke. The team used instruments that were orders of magnitude less precise than Marcy’s and Butler’s fine-tuned machinery. They weren’t even looking for planets. They were looking for something much bigger: huge failed stars called brown dwarfs.

What they discovered turned out to be a planet circling a star about 40 light-years away called 51 Peg. It was relatively easy to find because it was large--half the size of Jupiter--and very close to its star, where it exerted more of a tug and caused a bigger wobble--one that could be detected without the technique developed by Marcy and Butler. At 3,600 degrees, the “hottie” wasn’t a candidate for living creatures. But it was a planet--one that Marcy and Butler could have found.

Perfectionists to the end, Marcy and Butler had been fine-tuning their technique when they might have been planet hunting.

“It may have been the wrong decision,” Vogt says now.

Marcy sees it differently. He didn’t find the first planet, but he pioneered a scientific method capable of finding many more.

Marcy, Butler and Vogt would find their first planet--around the star 70 Vir--just two months later. They would go on to find five of the first six extrasolar planets and the only ones that scientists believe are remotely capable of harboring life because they could contain water. They have since discovered two-thirds of the 67 extrasolar planets found, more than any of the many teams that have joined the now fashionable hunt.

“I liken them to two guys who went to California in 1849 and found the mother lode,” said Alan Boss, a planetary theorist at the Carnegie Institution of Washington. “Now they’re mining their claim for all it’s worth.”

Once relegated to a scientific backwater, Marcy and Butler now work for two of the nation’s leading scientific research institutions. Marcy is a full professor at UC Berkeley, while Butler has joined the ranks of the Carnegie Institution in Washington. The two have been honored by the National Academy of Sciences, saluted by Gov. Gray Davis, even featured on the David Letterman show.

“History is written by the victors, so you want to be on the right side,” said Boss, a onetime skeptic who has became so impressed with the two that he has written a book about their efforts titled “Looking for Earths.”

Marcy and Butler’s team has gone on to locate solar systems with multiple planets, solar systems with planets in synchrony, and one solar system with a “whopper” object thought to be at least 17 times the mass of Jupiter.

“I keep waiting for the euphoria of boredom to set in so I can go back to my regularly scheduled life,” Marcy said. “But every time we think we’ve found everything, we find something else.”

The question that drives them on is the same one that first prompted them to gaze at the heavens above suburban Los Angeles. Is there another Earth out there? A planet with life like our own?

The odds are not bad. Marcy believes half of the 200 billion stars in the Milky Way have their own planetary systems. That means there could be billions, if not trillions, of planets in our own galaxy.

In the next 15 years, the National Aeronautics and Space Administration’s Jet Propulsion Lab, with Marcy’s help, plans to launch two space telescopes sensitive enough to detect the smaller wobbles created by Earth-sized planets and powerful enough to take the first picture of those planets.

Marcy can hardly wait for the next phase, believing, as he does, that the ultimate discovery could be only a decade away.

Marcy may be a grown man now and a luminary in his field with the world’s largest telescopes at his disposal. But he is not so far away from his battered 4 1/4-inch telescope and dog-eared science fiction paperbacks. When Marcy talks about distant worlds out there amid the stars, he is still 14. He is still on his parents’ roof.

“Let’s be honest,” he said from his Berkeley office. “Every 8-year-old knows there’s Earth-like planets out there.”

‘We’ve got planetary systems coming out of our ears. Planet hunting has morphed from the magnificent to the mundane.’

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How to Find a Planet

1. First, find a star

Since planets don’t produce their own light, they are impossible to see from far away. So planet hunters first find a star, then determine if a planet is affecting the star’s movement.

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2. Analyze the light

After finding a suitable star, scientists use a spectrometer to break up the star’s light into tens of thousands of colors. The colors tell astronomers how a star is moving.

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3. Plot the results

Planet hunters then plot the movement of the star on graphs.

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*A positive value indicates that the star is moving away from the Earth, while a negative value indicates that the star is moving toward Earth.

Source: G. Marcy, UC Berkeley

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