A Renaissance in the Search for Planets

Article excerpt

For millennia, man-kind has pondered and searched for worlds outside our solar system - for planets like Earth that could support life.

But since the advent of modern astronomy centuries ago, detection of distant planets has proved to be as difficult as finding grains of sugar on a beach. Stars, billions of times more brilliant than the worlds that circle them, make planets all but impossible to find. And decades of intense observation yielded only false alarms, earning planet-hunting a reputation as a backwater of astronomy.

During the past three years, however, this perception has radically changed. Through advances in technology, an improved understanding of planetary behavior, and increased access to better telescopes, astronomers have found 17 planets since 1995. These discoveries have revolutionized planetary science, forcing scientists to revise long-held theories about the universe and making planet- searching one of the hottest fields of astronomy. "The major change has been access to large telescopes like the Keck {a telescope in Hawaii with a mirror 30 feet across}," says William Cochran, an astronomer at the University of Texas at Austin. "With big scopes, you get a lot more light. And the faster you can get light, the faster you can detect these planets." In many ways, the recent discovery of what could be a nascent solar system 220 light-years from Earth is a symbol of this planet- hunting renaissance. Images of the would-be solar system were first captured by the Keck telescope. Later, using the Hubble Space Telescope, University of Hawaii astronomer Bradford Smith discovered that there might be a planet within the new solar system. He found the planet by searching the heavens in a different way - by looking at disks of dust around stars. He sifted infrared images of the star 220 light years away, dubbed HR 4796A. Inside its disk sat a ring that looked like hula hoop. "When we pulled the image of this star ring up on the computer screen, it looked like Saturn," says Dr. Smith. "It was like, 'Wow!' We had not really expected that." The same image that floored Smith brought a room full of normally sedate astronomers to their feet for a standing ovation at the American Astronomical Society meeting earlier this month. Indeed, the find is a breakthrough. According to previous theories, no planetary candidate should be there. The star is only 8 million to 10 million years old, supposedly far too young to have developed a large, far-flung planet like the one indicated in the Hubble images. But that's really no great surprise. Beyond the quixotic object found by Smith in the gloaming of deep space, astronomers are finding other planets that do not conform to traditional models. …