Accounting for all the other viewing angles not observed by Kepler and extrapolating from the data, the study finds that 22 percent of sun-like stars in the Milky Way have planets one- to two times the size of Earth orbiting in their habitable zones.
With about 50 billion sun-like stars in the galaxy, that means about one out of every five stars, or roughly 10 billion, have an Earth-sized planet in its habitable zone.
"This is the first time that a team has offered such a number for stars like the sun based on a thorough detection analysis," said Kepler mission science Natalie Batalha, with NASA's Ames Research Center in Moffett Field, Calif., told reporters on a conference call.
Earlier this year, another team of scientists reported that about 15 percent of cooler, red dwarf stars have potentially habitable planets.
"This team is pushing that to hotter stars, stars more like our sun," Batalha said.
The research is published in this week's Proceedings of the National Academy of Sciences.