NASA: Astronomers discover Earth-like planets believed to have oceans

Astronomers have discovered three Earth-like planets using NASA's Kepler Space Telescope, two of them potentially enveloped by water oceans with the right conditions for life.

The so-called super-Earths, Kepler 62e and 62f, orbit a single star in the Lyra constellation, about 1,200 light years away. They are part of a group of five exoplanets (the other three are too hot and inhospitable), and the star is smaller and cooler than the sun.

"These two planets are our best candidates for planets that might be habitable," said Bill Borucki, principal investigator of the Kepler telescope. There could be more planets in the star system that have yet to be detected, he added.

A third potentially habitable planet, Kepler 69c, orbits a sun-like star about 2,000 light years away, and scientists believe it's a rocky planet but are less certain about its environment. The distance to its star could make it a super-Venus instead of a super-Earth.

The two potential water worlds would have rocky cores, and computer models by the Harvard-Smithsonian Center for Astrophysics show one of the planets might be cloudier than Earth, while the other would require greenhouse gases to keep the water from freezing over.

Kepler 62e is about 40 percent larger than Earth and orbits its star every 122 days, while Kepler 62f is about 60 percent larger than Earth and orbits in 267 days.

Lisa Kaltenegger, a lead author of the findings, cautioned that the potential for water must be taken with a grain of salt because astronomers don't yet have the capability to measure the planets' mass and atmospheres.

Kaltenegger speculated that birds may have evolved there, in addition to the numerous possibilities of aquatic life.

"There may be life there, but could it be technology-based like ours?" she said in a statement. "Life on these worlds would be under water with no easy access to metals, to electricity, or fire for metallurgy. Nonetheless, these worlds will still be beautiful blue planets circling an orange star - and maybe life's inventiveness to get to a technology stage will surprise us. "

NASA's announcement added seven confirmed planets to the total discoveries by Kepler, the space telescope that has trained a continuous eye on one patch of sky since 2009. Astronomers have identified nearly 3,000 potential planets through the transit method of detection, measuring miniscule dips in starlight as planets orbit around.

Kepler's planetary survey will eventually help astronomers make statistical models of how many exoplanets are in the universe and where they might be, said Wes Traub, chief scientist with the Exoplanet Exploration Program at Jet Propulsion Laboratory.

That could mean more and more findings such as the two water worlds in the coming years.

"This is a great thing, because this is the whole reason Kepler was funded and is flying," said Traub, who was not involved in the findings announced Thursday.

One of the potential water worlds, Kepler 62f, was found through a new brightness detection method developed by University of Washington astronomer Eric Agol and graduate assistant Brian Lee. The Kepler software initially lacked the data to identify the planet.

"It isn't exactly the same as Earth. It is slightly larger and cooler than Earth," Agol said. "It tells me how special the Earth is and how it may take some time - hopefully not too long - to find its exact twin. "

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