In the past, it took lengthy and arduous ground-based telescopic observations to winnow impostors like double stars and other pretenders from the planet list. But the numbers have grown too large, the cosmos too verdant, for this case-by-case analysis.

The new results rely on a statistical technique developed by Timothy Morton, an astronomer at Princeton University, to vet the potential candidates in bulk, by analyzing the shape of the dips they make in starlight and taking into account how common the various types of impostors are and assigning a reliability score to each one.

“Planet candidates can be thought of like bread crumbs,” said Dr. Morton in a NASA teleconference on Tuesday. “If you drop a few large crumbs on the floor, you can pick them up one by one. But if you spill a whole bag of tiny crumbs, you’re going to need a broom. This statistical analysis is our broom.”

So far, two dozen of the planets found and confirmed by Kepler occupy the so-called Goldilocks zones of their stars where liquid water and perhaps “Life as We Think We Know It” could exist.

Extrapolating these results to the entire galaxy, Natalie Batalha, Kepler mission scientist from the Ames Research Center, said there could be 10 billion roughly Earth-size planets in the galaxy within their stars’ habitable zones. The nearest habitable planet, she estimated, could be as close as 11 light-years. In the cosmic scheme of things, that is next door and reachable in our lifetimes with current or near-future technology. Last month, scientists announced a plan to try to send smartphone-like spacecraft to Alpha Centauri, which is 4.4 light-years away.