#ICYMI: Earlier, we identified 219 potential new worlds from @NASAKepler data, ten of which are near-Earth size: https://t.co/Lh0O09jc0G pic.twitter.com/1bEFpXcrBy — NASA (@NASA) June 20, 2017
Nasa said this was the eighth release of the survey and the most comprehensive and detailed so far. It includes 4,034 planet candidates identified by Kepler. Of those, 2,335 have been confirmed to be exoplanets.
Kepler is the first space telescope capable of finding Earth-sized planets in or near the habitable zone.
Before its launch, astronomers had hoped that the frequency of Earth-like planets would be about one percent of the stars.
The talk among scientists at a Kepler conference in California this weekend is that it is closer to 60%, Alan Boss, an astronomer at the Carnegie Institution, said.
Kepler is not the only way astronomers have found exoplanets, and even potentially habitable ones. Between Kepler and other methods, scientists have now confirmed more than 3,600 exoplanets and found about 62 potentially habitable planets.
"This number could have been very, very small," said Caltech astronomer Courtney Dressing. "I, for one, am ecstatic."