The Glare of Other Suns: An Inside Look at How Astronomers Are Searching for Extrasolar Planets

Article excerpt

THE MAIN ROAD ON PALOMAR MOUNTAIN ENDS AT A cottage called the Monastery. The Monastery houses sleeping astronomers during the day so they can look into the sky at night. Opening a Monastery blackout shade in midday is like emerging from a matinee. The light of Southern California hurts when training to bear the night.

At around 4 pm on a clear day in December, I rolled out of bed to eat an early dinner prepared by Dipali Crosse, an earnest woman who makes tasty food from the kind of enormous boxes and cans that weigh down the shelves at Costco. Her food is fit for lumberjacks. This is our one good meal of the day. At the oak table, astronomers are already sitting shoulder to shoulder, some chairs angled around inconvenient corners. The Monastery has 12 rooms. On a normal observing run, only a few are occupied. But this week, the place is full. A few even had to shack up at the reservation casino a couple thousand feet down Palomar Mountain. Everyone is in town to see planets. Around stars hundreds of light years away, we now know there are other worlds. But they are impossibly faint, ghosts around the already dim suns that sustain them. On this trip, the light of those stars will be collected and then pared to find the planets in their orbit.

I had first seen the instrument that does the paring at Ben Oppenheimer's lab at the American Museum of Natural History (I also work at the AMNH as a biologist in the Genomics Department). Oppenheimer is an astrophysicist and his is one of only three ground-based systems designed to visualize extrasolar planets. With its cover off nearly 19 optical surfaces sat exposed, each beaming light to another, and ultimately to a coronograph, a device that functions as an occulter, and is at the heart of any astronomical instrument designed to see things other than stars. Oppenheimer and his colleagues have been working on this instrument for nearly six years. Dubbed Project 1640, the technology uses adaptive optics to calm the distortions inflicted by atmospheric turbulence, and speckle suppression to dampen the residual diffractive light that remains from the star even after it has been occulted. Twenty-three computers automate the synergy of nearly 4,000 movable parts. On a five night observing run on the 200-inch Hale telescope--the largest at Palomar and one of the largest in the world--the detector will collect 500GB of data. But most of the data, most of the light, is useless. The instrument must cut through the glare of the nighttime sky to image shy planets. Light from a star saturates its satellites. The starlight itself is extraneous, annoying even. "Once you've taken the best picture your technology will allow" said Oppenheimer, "you have to delete it." One photon in ten million comes from the world Oppenheimer most wants to see. It's like staring into the light of a thousand suns or searching for Venus at noon. Oppenheimer deletes his way to clarity.

We end dinner with obscene amounts of coffee, and head to the telescope at dusk. Sasha Hinkley, a postdoc in astrophysics at Caltech and one of Oppenheimer's former students, is already there, suspended from the end of the telescope in the Cassegrain cage. The cage is a metal enclosure that cradles the five-meter mirror, forming a giant cup with access to the Hale's key optics and Project 1640's instrument. The telescope dwarfs the cage. It rises nearly 13 stories wrapped in a white dome of precious steel borrowed from the industrial machine of WWII America. On the outside about three quarters of the way up, a catwalk skirts the dome and moves as the telescope slews so that astronomers catching a quick smoke might see the lights of Temecula give way to the steady glow of LA County without lifting a foot. The dome is otherworldly whether you're in it, on it, or looking at it in full moonlight as I did on my first night. Against the dark sky it stands in blanched relief, a functional monument, every part of its interior and exterior curvature accessible and working. …