Planet hunters are significantly closer to their goal of finding an "Earth twin" with the discovery of two planets similar in size to our own, astronomers with NASA's Kepler mission announced today.
The planets, described at a NASA press conference, orbit a sun that's cooler than ours but is at the right distance to allow water to remain liquid, which is considered essential for a planet to support life. (Read about a related discovery in 2011: "NASA's Kepler Finds Two Earth-Size Planets Around Sunlike Star.")
And because of their sizes and orbits, the newfound planets are likely either rocky—like Earth—or watery, NASA scientists said. The two planets are located 1,200 light-years away in a five-planet system orbiting a star dubbed Kepler-62.
Called Kepler-62e and -62f, the planets "are by far the best candidates for habitability of any found so far," said William Borucki of NASA's Ames Research Center, the science principal investigator for the agency's Kepler Space Telescope.
"If you were on Kepler-62f and looking at the sun, it would be a little less yellow than ours," said Borucki, whose announcement coincided with the release of a study on the topic in the journal Science.
"And at sunset the sky would be more red. But otherwise it would basically look and feel the same," he said.
"I would call this a breakthrough discovery."
The press conference also introduced another study released today in the Astrophysical Journal, which involves a related discovery of a sun very much like our own named Kepler-69.
http://news.nationalgeographic.com/news ... pler-nasa/
