Astronomers are closer than ever to finding a near twin for the Earth, they said Tuesday, announcing the discovery by the National Aeronautics and Space Administration (NASA) of eight new planets that circle in the habitable zones of their stars. Two of the eight are the most Earth-like of any known planets found so far outside our solar system, astronomers told the 225th meeting of the American Astronomical Society in Seattle, Washington. The two are likely to have rocky surfaces in addition to being an orbiting distance form their stars that is neither too hot nor too cold for liquid water to form and possibly life to exist, astronomers said. The discovery doubles the number of known planets that are close in size to the Earth and receive about the same amount of heat from their stars as we get from the sun. "We are now closer than we have ever been to finding a twin for the Earth around another star," said Fergal Mullally of NASA's Kepler Science Office. "These candidates represent the closest analogs to the Earth's own system found to date." The worlds were found with the help of the U.S. space agency's planet-searching Kepler mission, a space telescope that has examined more than 150,000 stars for planets beyond our solar system since its launch in 2009. NASA announced Tuesday that Kepler confirmed its 1,000th planet outside the solar system, the vast majority unlike Earth.
