Are there Extraterrestrial planets like 'Earth' exist in space? <br />Habitable alien planets similar to Earth may not be that rare in the universe, a new study suggests. <br />About one in five sunlike stars observed by NASA's planet-hunting Kepler spacecraft has an Earth-size planet in the so-called habitable zone, where liquid water - and, potentially life - could exist, according to the new study. If these results apply elsewhere in the galaxy, the nearest such planet could be just 12 light-years away. <br /> <br />"Human beings have been looking at the stars for thousands of years," said study researcher Erik Petigura, a graduate student at the University of California, Berkeley (UC Berkeley). "How many of those stars have planets that are in some way like Earth?
