A team of planet hunters estimates that about 22 percent of the Sun-like stars in our galaxy may have planets about the size of Earth that are bathed in similar amounts of sunlight — and potentially habitable. That's the conclusion of a new analysis by Erik Petigura, a graduate student at the University of California, Berkeley of observations taken by NASA's Kepler Space Telescope, which was launched in 2009 to hunt for potentially habitable Earth-like planets around other stars.
In an NPR Interview with Harvard Astronomy Professor Charbonneau he states that researchers have "done a careful study, and the results are very interesting." But he notes that the team did not detect a single planet that is the same size and temperature as Earth. Instead, he points out, the group found planets that are larger and hotter and used them to calculate the prevalence of more Earth-like worlds. "The analysis of the Kepler data is by no means finished, and with dedicated effort it may be possible to further clean out the noise and some true Earths may pop out — but for now we have to be satisfied with knowing the population of planets that are broadly Earth-like, but in truth are probably too big and too hot for life,"
Link: http://www.wbur.org/npr/242991030/galaxy-quest-just-how-many-earth-like-planets-are-out-there