NASA discovers Earth-sized planet that may sustain life

NASA: Kepler planet may be habitable
NASA: Kepler planet may be habitable


    NASA: Kepler planet may be habitable


NASA: Kepler planet may be habitable 00:32

Story highlights

  • Researchers find an Earth-sized planet that may be habitable
  • It "proves the existence of worlds that might be similar to our own," institute says
  • Scientists are looking for emissions that could suggest extraterrestrial life
  • Previously discovered worlds were larger than Earth



"This is the first definitive Earth-sized planet found in the habitable zone around another star," said Elisa Quintana of the Search for Extraterrestrial Intelligence (SETI) Institute at NASA. "Finding such planets is a primary goal of the Kepler space telescope."

"This discovery not only proves the existence of worlds that might be similar to our own but will undoubtedly shape future investigations of exoplanets that could have terrestrial surface environments," the institute said in an announcement Thursday.

2011: Searching for life beyond Earth
2011: Searching for life beyond Earth


    2011: Searching for life beyond Earth


2011: Searching for life beyond Earth 02:24


The size -- estimated to be 10% larger than Earth -- and distance from its star don't just make for interesting factoids. They give scientists hope that Kepler-186f might sustain life as we know it.

Of nearly 1,800 "confirmed exoplanets" that have been found, approximately 20 orbit their host stars within habitable zones, where it's believed surface water would not freeze or boil. In 2011, NASA announced that Kepler had observed five planets approximately the size of Earth and in the habitable zone.

But the "previously discovered worlds are larger than Earth, and consequently their true nature -- rocky or gaseous -- is unknown," the SETI Institute said in a written announcement on Thursday. "On the basis of the observed dimming of starlight from Kepler-186, the authors estimate that this newly discovered planet is roughly the same size as the Earth."


Even if Kepler-186f is rocky, it's not necessarily habitable, scientists warned Thursday. First, a lot would depend on the atmosphere, if it has one, Thomas Barclay of NASA's Kepler mission said. And scientists right now don't have the technology to know what the atmosphere is.

The star's size -- it's an M-dwarf star, smaller and less hot than our sun -- also could come into play. Because it is smaller, the habitable zone is closer, so radiation could prevent life if the atmosphere isn't dense enough, said Victoria Meadows of the University of Washington Virtual Planetary Laboratory.



For researchers, the discovery of Kepler-186f is like a beginning. It's a first but "not a record we wish to keep," Quintana said. "We want to find more of these."
