Most 'Earth-like' planet yet is discovered

MOFFAT FIELD, Calif., Dec. 5 (UPI) -- U.S. astronomers say an Earth-like planet outside the solar system is in its star's "habitable" zone with a surface temperature averaging a balmy 72 degrees.

The planet discovered by the Kepler space telescope orbits a star about 600 light years away, close by astronomical standards, researchers announced Monday at NASA's Ames Research Center in Moffett Field, Calif.

"It is right smack in the middle of the habitable zone," Kepler scientist Natalie Batalha told USA Today.

The discovery of the planet, dubbed Kepler 22b, caps years of searching for a "Goldilocks" planet -- one not too hot and not too cold -- that could harbor oceans on its surface, like Earth, since liquid water is considered vital for the development of life.

"This is a phenomenal discovery in the course of human history," said planet hunting pioneer and Kepler investigator Geoff Marcy of the University of California-Berkeley.

A rush of exo-planet discoveries followed the first 1995 confirmation of a planet orbiting a nearby star in 1995, mostly jumbo planets the size of Jupiter or larger.

Kepler 22b "is the smallest, most nearly Earth-size, planet ever found in the lukewarm zone around another sun where life could thrive," Marcy said.

"We homo sapiens are straining our reach into the universe to find planets that remind us of home," Marcy said. "We are almost there."