Scientists have discovered a planet not too much bigger than
Earth that's circling a distant star that's much like our own
sun. What's more, this planet is in the "Goldilocks zone" around
that star — a region that's not too hot and not too cold. That's
the kind of place that could be home to liquid water and maybe
even life. The planet, known as Kepler-22b, is the first near-
Earth-sized planet to be found smack dab in the middle of the
habitable zone of a twin to our Sun. The planet is about 2 1/2
times the size of the Earth. It orbits a little closer to its
star than our planet does to our sun, and goes around once every
290 days compared with our 365. But its star is a bit cooler
than our sun, says William Borucki of NASA Ames Research Center,
who heads NASA's Kepler space telescope mission, which detected
this planet. "That means that that planet, Kepler-22b, has a
rather similar temperature to that of the Earth," Borucki says.
"Its surface temperature would be something like 72 Fahrenheit."
It's not yet c