Using Kepler data, astronomers estimate that a sizeable fraction of sunlike stars have possibly habitable planets
The galaxy contains billions of potentially habitable Earth-sized planets, according to even the most conservative estimate drawing on data from NASA’s Kepler space telescope.
Although a mechanical failure recently put the telescope out of commission (SN: 6/15/13, p. 10), Kepler’s census of planets orbiting roughly 170,000 stars is enabling astronomers to predict how common planets similar to Earth are across the galaxy.
The authors of a study published November 4 in the Proceedings of the National Academy of Sciences conclude that between 14 and 30 percent of stars similar in mass and temperature to the sun host a possibly habitable planet. Such a planet has a diameter as large as Earth’s is but no more than twice it; the planet also orbits in a star’s habitable zone, a