3rd LD: NASA's planet-hunting Kepler Telescope spots Earth's close cousin

Scientists using planet- hunting Kepler space telescope have discovered a new catalog of exoplanet candidates and confirmed the first near-Earth-size planet in the "habitable zone" around a sun-like star, NASA announced during a press conference Thursday.

Though NASA said it can't say for sure whether the planet is rocky like ours or has water or air, the newly discovered Kepler- 452b is the closest match yet found. Previous research suggests that planets the size of Kepler-452b have a good chance of being rocky.

"On the 20th anniversary year of the discovery that proved other suns host planets, the Kepler exoplanet explorer has discovered a planet and star which most closely resemble the Earth and our Sun," said John Grunsfeld, associate administrator of NASA 's Science Mission Directorate at the agency's headquarters in Washington. "This exciting result brings us one step closer to finding an Earth 2.0."

The new catalog includes 12 candidates that are less than twice Earth's diameter, orbiting in the so-called habitable zone of their star. This zone is the range of distances at which the energy flux from the star would permit liquid water to exist on the planet's surface.

Kepler 452b, about 1,400 light years from Earth in the constellation Cygnus, is the first to be confirmed as a planet of these candidates.

The planet is about 60 percent bigger in diameter than Earth and is considered a super-Earth-size planet and the smallest planet to date discovered orbiting in the habitable zone -- the area around a star where liquid water could pool on the surface of an orbiting planet -- of a G2-type star, like our sun. The confirmation of Kepler-452b brings the total number of confirmed planets to 1,030.

Kepler 452b accompanies a star whose characteristics are very similar to the Sun: it is 4 percent more massive and 10 percent brighter. Kepler-452b orbits its star at the same distance as Earth orbits the Sun.

"This discovery and the introduction of 11 other new small habitable zone candidate planets mark another milestone in the journey to finding another 'Earth'", NASA said.

With a new release of the seventh Kepler planet candidate catalog on Thursday, the catalog of exoplanet candidates adds 521 new possible planets to the 4,175 already found by the famed space- based telescope. Endite