Scientists have statistically determined that one in five Sun-like stars in our galaxy have Earth-sized planets that could host life.
The findings, gleaned from information collected from NASA's Kepler spacecraft and the W. M. Keck Observatory, now satisfy Kepler's primary mission: to determine how many of the 100 billion stars in our galaxy have potentially habitable planets.
UC Berkeley graduate student Erik Petigura, who led the analysis of the Kepler and Keck Observatory data, said that what this means is, when you look up at the thousands of stars in the night sky, the nearest sun-like star with an Earth-size planet in its habitable zone is probably only 12 light years away and can be seen with the naked eye.
Andrew Howard, astronomer with the Institute for Astronomy at the University of Hawaii, said that for NASA , this number - that every fifth star has a planet somewhat like Earth - is really important, because successor missions to Kepler will try to take an actual picture of a planet, and the size of the telescope they have to build depends on how close the nearest Earth-size planets are.
He said that an abundance of planets orbiting nearby stars simplifies such follow-up missions.
The results have been published in the journal Proceedings of the National Academy of Sciences.