... Star Atlas . ... At least one in six stars has an Earth-sized planet . ... Key findings include the fact that one in six stars hosts an Earth-sized planet in an orbit of 85 days or less, and that almost all Sun-like stars have a planetary system of some sort. ... Using NASA's Kepler spacecraft, astronomers are beginning to find Earth-sized planets orbiting distant stars. A new analysis of Kepler data shows that about 17 percent of stars have an Earth-sized planet in an orbit closer than Mercury. ...