The needle-in-a-haystack search for extraterrestrial signals has narrowed a bit, thanks to NASA's Kepler spacecraft.
Scientists announced that, of the 1,235 candidate planets discovered by Kepler, 54 of them were in what's known as the Goldilocks zone, a region close enough to its home sun where a planet may harbor life.
When NASA informed the SETI Institute (Search for Extraterrestrial Intelligence) of these possibilities, the California-based institute turned the Allen Telescope Array in the location of those planets and began listening for any signs or signals of intelligent life.
NASA / Time & Life Pictures / Getty Images
SETI senior astronomer Seth Shostak says he and his colleagues were thrilled about the prospect of 54 possible habitable planets.
"Well, that is obviously great! Although we've known about planets, the big question is always how many of those planets are, in fact, possibly cousins of Earth, that could support life?
"It's nice to know that they're not extraordinarily rare. If you'd asked this question 50 years ago -- and it was asked -- they had to sort of guess at whether planets like Earth were common or otherwise," Shostak told AOL News.
All of the data gathered from the Kepler mission suggests that Earth-like planets are not as rare as once thought. Shostak explains that the candidate numbers are pretty huge.
"It's the percentage of star systems that might have a world something like Earth. It's not one in a million, it's not one in 100,000, it's not even one in 1,000. Every 100 star systems are going to have a couple of these guys, and maybe more."
"All it means is that maybe a lot of them have life, but how much of that life is at the stage of being technically able to get in touch with you?" he pointed out.
"Of course, we will look at every planet that they find that has any chance of having some sort of complex life on it. But to me, the big picture is something else: Since these sorts of worlds occur on the percent level, that means there are literally billions of candidates for being Earth's cousins in the Milky Way. And billions is a big number!"
So far, after their initial telescopic survey of the planets found by Kepler, SETI scientists haven't yet detected that smoking-gun alien signal.
"It could've turned out that planets were rare -- well, that's not true. It could've turned out that Earth-like planets are rare -- there's no indication that's true, either," said Shostak.
"For 50 years, we've been saying intelligent life might be reasonably common. It might not be a miracle, and we might not be the only kids on the block."