NASA didn't plan it this way, but earlier this month a co-investigator on the Kepler satellite mission in the hunt for other Earth-like planets announced to a conference in Oxford, England, that "planets like our own Earth are out there. Our Milky Way galaxy is rich in this kind of planet." The announcement—which wasn't getting out until conference organizers posted a video online last week—was especially striking because it was largely based on Kepler data that team members had been allowed to keep to themselves for further analysis until next February. So, traditionally, such data would be released formally with all involved scientists onboard.
The all-too-public leak came from astronomer and Kepler co-investigator Dimitar Sasselov of Harvard University at the annual TEDGLobal conference, a production of the nonprofit TED.
At 8:15 into his 18-minute talk, Sasselov showed a bar graph of planet size. Of the approximate 265 Kepler planets represented on the graph, about 140 were labeled "like Earth," that is, having a radius smaller than twice Earth's radius. "You can see here small planets dominate the picture," said Sasselov. Until now, astronomers' exoplanet finds had been more like gas giant Jupiter than rocky little Earth. Even Kepler investigators had refrained from discussing any Earth-size finds.
Sasselov did emphasize that these are candidates, not confirmed exoplanets. With further observation, half of them could well turn out to be false alarms. Many could also be Earth-like in size but orbiting so close to their stars that nothing but their size would be Earth-like. Sasselov said that astronomers will be able to identify at least 60 Earth-like planets. So the unauthorized presentation of preliminary results would seem to confirm that Kepler has succeeded in showing that Earth is no fluke.
NASA has yet to comment.