Dr. David Koerner was getting groggy. It was 2 a.m. in the control room on top of Hawaii’s dormant volcano Mauna Kea, where he and a team of astronomers were operating a special infrared camera with one of the world’s largest telescopes, the Keck II. The late hour and oxygen-thin air—at 14,000 feet above sea level—were making him tired, so the scientist had settled back to rest while a colleague from NASA’s Jet Propulsion Laboratory began searching for the next star on their list, unimaginatively named HR 4796.
    But the 10-million-year-old object seemed to have disappeared when viewed at mid-infrared wavelengths. With his colleague growing exasperated, Koerner perked up and wondered if the object were more elongated than they thought; he made a few adjustments to the instrument. Suddenly, from 220 light years away, in the constellation Centaurus, an unexpected image appeared on the computer screen.
    “We’d been staring at it the whole time,” says Koerner, now an assistant professor of physics and astronomy at Penn. “We thought we couldn’t even see the star. Next thing, we found a star with a disk” around it. “We went ballistic.”
    He ran into the kitchen to rouse the others from their break. Almost immediately, they noticed that the dust- and gas-filled disk was brighter on the ends than in the center. That seemed strange. “We were saying, ‘Wow, does that thing have a big hole in it?’” It did, in fact—an empty region 100 astronomical units (A.U.) in diameter, just larger than our own solar system. (One A.U. equals the distance from the Earth to the Sun.) What they were looking at was likely a hole that had been cleared out by planets forming.
    “I went out and walked around the mountain to try to slow the adrenaline,” recalls Koerner. “And I remember thinking, ‘Oh no, this is going to be a real stressful ride.’”