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