Scientists have found two Earth-sized planets orbiting a star outside the solar system

The discovery shows that such planets exist and that they can be detected bythe Keplerspacecraft, said FrancoisFressin of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.They're the smallest planets found so far that orbit a star resembling our sun.
Scientists are seeking Earth-sized planets as potential homes forextraterrestrial life, said Fressin, who reports the new findings in a paperpublished online Tuesday by the journal Nature. One planet's diameter is only 3percent larger than Earth's,while the other's diameter is about nine-tenths that of Earth. They appear tobe rocky, like our planet.

But they are too hot to contain life as we know it, with calculatedtemperatures of about 1,400 degrees and 800 degrees Fahrenheit, he said.
Any life found on another plant may not be intelligent; it could be bacteriaor mold or some completely unknown form.
Since it was launched in 2009, NASA's planet-hunting Kepler telescope hasfound evidence of dozens of possible Earth-sized planets. But Fressin's reportis the first to provide confirmation, said Alan Boss of the Carnegie Institution for Sciencein Washington. He's a member of the Kepler science team but not an author ofthe paper.
The researchers ruled out a possible alternative explanation for the signalsthat initially indicated the planets were orbiting the star Kepler-20. The staris 950 light-years from Earth in the direction of the constellation Lyra.
The planets, called Kepler-20e and Kepler-20f, are part of a five-planetsystem around the star, and their location challenges current understanding ofhow planets form, scientists said. In our own solar system, the small rocky planets areclosest to the sun, while gaseous giants are on the periphery. But thefive-planet system has no such dividing line; big and small planets alternateas one move away from the star.
That's "crazy," and unexplained by current understanding of howplanets form around stars, said study co-author and Harvard scientist DavidCharbonneau.
Earlier this month, scientists said they'd found a planet around anotherdistant star with a life-friendly surface temperature of about 72 degrees. Butit was too big to suggest life on its surface. At 2.4 times the size of Earth,it could be more like the gas-and-liquid Neptune with only a rocky core andmostly ocean, scientists said.