NASA's Kepler finds 10 more Earth-like planets
NASA has announced the discovery of 10 rocky, Earth-sized planets in our Milky Way Galaxy that could potentially have liquid water and support life.
The US space agency released on Monday a survey of 219 potential exoplanets - planets outside of our solar system - that had been detected by its Kepler space telescope between its launch in 2009 through its first four years in space.
Ten of the new discoveries were orbiting their suns at a distance similar to Earth's orbit around the sun, the so-called habitable zone - meaning surface temperatures could support liquid water and, hypothetically, life.
That does not mean the planets have life, but some of the most basic requirements that life needs are there.
"Are we alone? Maybe Kepler, today, has told us indirectly, although we need confirmation, that we are probably not alone," Kepler scientist Mario Perez said in a news conference.
Outside scientists agreed that this is a boost in the hope for life elsewhere.
"It implies that Earth-size planets in the habitable zone around sun-like stars are not rare," Harvard astronomer Avi Loeb, who was not part of the work, told the Associated Press news agency in an email.
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 percent, 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."