NASA's Planet Hunter Starts Hunting
An artist's interpretation of the Kepler observatory in space.
Credit: NASA.

NASA's Kepler spacecraft has begun its search for other Earth-like worlds, NASA announced today.

Kepler is designed to find planets as small as Earth that orbit sun-like stars at distances where temperatures are right for possible lakes and oceans.

Scientists and engineers have spent the last two months checking out and calibrating Kepler.

"Now the fun begins," said William Borucki, Kepler science principal investigator at NASA's Ames Research Center, Moffett Field, Calif. "We are all really excited to start sorting through the data and
discovering the planets."

The Kepler probe launched March 6. It will spend more than three years staring at more than 100,000 stars for telltale signs of planets passing in front of them.

"If Kepler got into a staring contest, it would win," said James Fanson, Kepler project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The spacecraft is ready to stare intently at the same stars for several years so that it can precisely measure the slightest changes in their brightness caused by planets."

Kepler will hunt for planets by looking for periodic dips in the brightness of stars -- events that occur when orbiting planets cross in front of their stars and partially block the light.

The mission's first finds — which could be announced as early as next year, the space agency said today — are expected to be large, gas planets situated close to their stars. Ground-based telescopes have found about 300 such gas giants already.