NASA’s Kepler space telescope has found 1202 possible exoplanets. The expectation is 90% of those will be confirmed. The Kepler telescope surveys only one four-hundredth of the sky, the numbers extrapolated to some 20,000 habitable-zone planets within 3,000 light-years of Earth.
Of the new candidates, 68 are one-and-a-quarter times the size of the Earth or smaller — smaller, that is, than any previously discovered planets outside the solar system. Another 50 of these so-called exoplanets are in the habitable zones of their stars, where temperatures should be moderate enough for liquid water, the essential stuff for life as we know it; two of these are less than twice the size of Earth.
In a separate announcement, to be published in Nature on Thursday, a group of Kepler astronomers led by Jack Lissauer of Ames said they had found a star with six planets — the most Kepler has yet found around one star, orbiting in close ranks in the same plane inside what would be the orbit of Mercury.