First Earth-Sized Exoplanet Discovered - ScienceNOW

First Earth-Sized Exoplanet Discovered - ScienceNOW

Astronomers have announced the discovery of an extrasolar planet not much larger than Earth—the smallest exoplanet yet found. Although the world orbits too close to its sun to sustain life, the finding is a milestone in the quest to find out how common Earth-sized, habitable planets really are. It also shows that, with some luck and some innovative new technology, astronomers could be announcing the discovery of a habitable Earth-like exoplanet within a few years.

Today's announcement, made at the winter meeting of the American Astronomical Society in Seattle, Washington, had been foreshadowed. Last year, team members operating the Kepler telescope orbiting the sun announced that they had found so many new exoplanets less than half the size of Jupiter that Earth-sized exoplanets must be abundant.

Now Kepler has found the much-anticipated first rocky, Earth-sized exoplanet. It did it by staring for months on end at the same 150,000 stars in the constellation Cygnus. Kepler's 1-meter-diameter telescope, hooked up to a sensitive light-measuring instrument, is capable of detecting the dimming of a star as a planet orbits in front of it—even if the star dims by only 0.01%. That's like detecting the dimming of 10,000 light bulbs when one burns out, noted Kepler deputy science team leader Natalie Batalha of NASA's Ames Research Center in Mountain View, California.