Scientists: 22 per cent of sun-like stars have Earth-sized planets
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Washington - Among stars of similar size and age to the sun, an estimated 22 per cent have Earth-sized planets, US-based scientists said Monday, extrapolating from studies of a sliver of the Milky Way.
Results published by a group of researchers from the University of California at Berkeley and the University of Hawaii at Manoa were based on data from the Keck Observatory in Hawaii and NASA's Kepler spacecraft.
"What this means is, when you look up at the thousands of stars inthe 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 beseen with the naked eye," said UC Berkeley graduate student Erik Petigura, who led the data analysis.
"That is amazing." He described the research as a "census of extra-solar planets." Launched in 2009, the now-crippled Kepler spacecraft studied a small segment - 150,000 stars - within Earth's own galaxy to spot the signature wobble of an orbiting planet passing in front of the star.
Knowing the relative rarity of planets having an angle of orbit visible from Earth, and with enough supplementary data from the Keck Observatory to judge the approximate diametres of planets, the project scientists were able to compute the frequency of Earth-like planets at 22 per cent, with a margin of error of 8 per centage points.//DPA
