Astronomers estimate 17 billion Earth-like planets in the Milky Way

BBC : At the 221st American Astronomical Society meeting, Christopher Burke of the Seti Institute announced that the number of planet candidates the Kepler space telescope had identified had reached 2740. Since 2009 Kepler has observed more than 150â000 stars in the same area of space. François Fressin of the HarvardâSmithsonian Center for Astrophysics and his colleagues have been examining the stars for minute dips in brightness that may be caused when a planet passes in front of one. By ruling out other possibilities, and by calculating the masses of the planets, Fressin’s team has determined that 17% of the stars have planets up to 1.25 times the size of Earth that have orbits of less than 85 days. That means that there may be more than 17 billion Earth-sized planets in the Milky Way.