海角大神

An astronomer鈥檚 job generally comes with breathtaking views from delightfully remote peaks, in observatories perched on mountaintops far from city lights. But tonight, Geoff Marcy is bunkered in the basement of a building so close to a rock concert that you can鈥檛 even find a parking space.

Yet he鈥檚 on a volcano. Kind of.

From a swivel chair in the basement of the astronomy department at the University of California, Berkeley, he鈥檚 directing the world鈥檚 largest functioning telescope, on Hawaii鈥檚 14,000-foot Mauna Kea volcano. Dr. Marcy鈥檚 remote-controlled system of interconnected computers, screens, and a real-time audiovideo connection shows him what the telescope is 鈥渟eeing鈥� 鈥� and it鈥檚 not the twinkling light of a distant star. Rather, the screens fill with the spectrum of colors that starlight produces. To the untrained eye, it鈥檚 no more than a blotch of 1960s psychedelia.

Marcy is a planet hunter, a kind of Indiana Jones of the astronomy world 鈥� supposing Jones had been armed with millions of dollars鈥� worth of stargazing technology instead of a whip and searched galaxies rather than jungles.

An astronomy professor at UC Berkeley, clad tonight in a Hawaiian shirt in homage to the telescope鈥檚 homeland, he has the rare privilege of 10 consecutive nights on the Keck, during which he鈥檚 searching for planets beyond our solar system.

His days are long: five to seven hours of daily preparation, during which he comes up with a 鈥渟cript鈥� of which stars he and his 鈥渁ce鈥� postdoctoral fellow, Andrew Howard, will look at that night; on top of that, there鈥檚 the routine calibration and testing of the scope 鈥� and all of this takes place well before nightfall in Hawaii.

As for the viewing, Marcy and Dr. Howard will work from about 10:30 p.m. to 7:30 a.m., sometimes with relief from a student who comes in at 4 a.m. This isn鈥檛 Marcy鈥檚 first time on the Keck 鈥� he鈥檚 spent more than 250 days on the telescope over the course of his career 鈥� but to have 10 days at a stretch is extraordinary, a privilege based partly on Marcy鈥檚 reputation and partly on a broader excitement about planet hunting.

Marcy has been searching for these 鈥渆xtrasolar planets鈥� longer than just about anyone else in the field, and his success has been, well, astronomical. He and his team have found nearly 150 planets so far 鈥� more than any other astronomer.

鈥淕eoff is one of the pioneers,鈥� says Alan Boss, an astronomer with the Carnegie Institution in Washington, D.C. 鈥淔ifteen years ago, there were just a dozen planet hunters. Today, there are hundreds.鈥� What Marcy and a few others touched off was something Dr. Boss calls 鈥淭he New Space Race鈥� 鈥� the race to find a planet like Earth.

Marcy began searching for extrasolar planets in 1983, a choice that was actually born of failure. He was halfway through a two-year fellowship, toiling on a subject having nothing to do with planets, when a prominent Harvard astronomer wrote that his work was all wrong. Marcy was devastated.

鈥淚 felt like my career was over before it had even begun,鈥� he says. 鈥淪o I decided that before I quietly went off to teach for the rest of my life, I would spend the second year of the fellowship doing what I really wanted to do.鈥�

His dream was to find a planet like Earth 鈥� a finding that 鈥渨ould supersede the discovery of fire.鈥� But no one had done it before; no one thought it was possible; and no one was seriously looking, because the technology was entirely inadequate. Planet hunting, recalls Marcy, was considered astronomy鈥檚 鈥渓unatic fringe.鈥�

鈥⑩赌⑩赌�

Astronomers have known, theoretically, how to find extrasolar planets since the early 1900s: Measure how much a planet moves its star. Marcy explains that every planet has a small gravitational pull on the star it orbits, which causes the star to move, or 鈥渨obble,鈥� a tiny bit.

Marcy illustrates this effect by asking me to grab his outstretched hand. I am sitting in a swivel chair, and Marcy, holding my hand firmly, runs around me in a circle. He is the planet; I am the star. I, of course, do not rotate on a perfect axis, but am pulled in a messy circle that leaves the rug beneath my chair a rumpled mess.

The demonstration is an exaggeration, but it makes the point. For a star, that tiny wobble causes small changes in the lightwaves it emits. Those changes 鈥� called Doppler shifts 鈥� are measurable now. But they weren鈥檛 in 1983, which is why Marcy had the field pretty much to himself.

鈥淭he technology then was like using a cop鈥檚 radar detector to measure the speed of a snail,鈥� he says. 鈥淚t just couldn鈥檛 be done.鈥�

So for 12 years, Marcy and a former student, Paul Butler, labored day and night to refine the technique of measuring stars鈥� lightwaves. They applied related solutions from other research, and honed their computer analysis until they were able to detect movement as slow as three meters per second. That鈥檚 about the speed of a medium-paced jogger.

In 1995, they hit the jackpot, detecting not one, but two planets. Although Marcy wasn鈥檛 the first 鈥� a Swiss team had found a planet about two months earlier 鈥� his discovery caused a scientific stir, a media firestorm, and something of a stampede into the field. These discoveries, says Boss, have made the pioneer planet hunters excellent candidates for a Nobel Prize.

A total of some 300 planets have been detected by astronomers so far. But all of them are considerably heftier than Earth. A few recent finds have been a mere five times the bulk, but most are equivalent to Saturn or Jupiter 鈥� about 100 to 300 times the mass of our beloved blue home. Which means they鈥檙e probably gaseous, or have little atmosphere and less water, and are therefore very unlikely to support life.

So the quest goes on.

鈥⑩赌⑩赌�

During this stint with the Keck, Marcy has targeted about 300 stars, all of which he suspects have one or more orbiting planets. With the help of Howard and a telescope operator in Hawaii, Marcy collects the stars鈥� light and directs it through a state-of-the-art spectrometer that breaks the light down into 100,000 shades of the rainbow spectrum. Those breakdowns form 鈥渟napshots,鈥� and by comparing many snapshots from each star, Marcy measures the Doppler shifts to determine if the stars are wobbling.

After days of crunching data using algorithms that Marcy and his team devised themselves, Marcy and Howard begin writing up their findings: This time, they鈥檝e found two 鈥渘ew鈥� planets that are nine and 10 times the size of Earth.
Marcy is also at work on technology to find ever-smaller planets. He expects astronomers to discover something the size of Earth in the next three years.

All of which raises the question: What then? At this, he lights up and outlines two options. The first is to look directly at the planet with a huge space-borne telescope. But this would be years away, as the telescope is not yet funded, much less designed or launched.

A second option is the old 鈥減hone home鈥� technique. Marcy would seek to contact the planet directly by beaming anything we鈥檝e got at them 鈥� X-ray, radio, and lightwaves 鈥� and 鈥渁sk them to fax us a picture of their planet.鈥�

It鈥檚 a typical Marcy-an response 鈥� funny and inquisitive. But the message is serious, and a bit like the caution on every side-view mirror 鈥� Warning: Extraterrestrial life is closer than it appears.