NASA discovers Earth-like planet in 'habitable zone'

NASA astronomers announced Thursday that they had

found an Earth-like planet roughly 1,400 light years away.

Other planets, such as Kepler-186f, have been discovered in this sweet Goldilocks spot that is neither too close nor too far to potentially sustain The newly discovered Kepler-452b, which is in the Cygnus constellation, orbits a star from what is called the habitable zone: the distance at which water can pool on the surface of a planet.

sustain life. But Kepler-452b is different because it circles a G2-type star — just like our sun.

"There's really one place that we know has life in the universe, and that's Earth, so finding another planet around a star that's very similar to our sun is quite exciting," NASA astronomer Jeff Coughlin said in an interview with Yahoo News.

The scientists are not necessarily saying that other types of stars, such as M-dwarfs, cannot sustain life. But there are many unknown factors about what sort of role they would play in creating or preventing it.Kepler-452b is roughly 60 percent larger in diameter than Earth but still has a good chance of being rocky like Earth rather than spacious like Neptune or Jupiter, according to NASA.

The Kepler spacecraft was launched in 2009 to collect and transmit data on potential Earth-like planets.

Coughlin, a Kepler scientist at the SETI Institute in Mountain View, Calif., explained that signs of periodic dimming and brightening are the first clues of a potential planet.

"The second step is to really delve in deep to the Kepler data itself," he said. "Take a really hard look and rule out all of the other possibilities of what could be causing the signal."

At that point, Coughlin said, the scientists consider the object of study a "planet candidate," but official confirmation relies on additional data outside of Kepler.

"They used ground-based telescopes to really observe the star better and rule out the remaining scenarios," he said. "That's when you call it confirmed. At the 99 percent level, this has to be a planet."

The ground-based observations were conducted at the McDonald Observatory at the University of Texas at Austin, the Fred Lawrence Whipple Observatory on Arizona's Mt. Hopkins and the W.M. Keck Observatory on Hawaii's Mauna Kea.

At a Thursday news conference in Cape Canaveral, Fla., scientists announced the discovery of Kepler-452b and 11 small new candidate planets that are in the habitable zone.

The research paper reporting the team's findings will appear in an upcoming issue of The Astronomical Journal.

"We've been analyzing the data as we got it from Kepler. And we've been finding planets that are closer and closer to being very much like the Earth," Coughlin said. "Kepler-452b is the next step. It's the closest we have. But the story is still going on."