60-Second Science

Earths Common as Dirt

Speaking at the annual meeting of the American Association for the Advancement of Science in Chicago on February 14th, astronomer Alan Boss, author of the new book The Crowded Universe, said that we're about to find out just how many habitable planets are out there--and he thinks there are sextillions. Steve Mirsky reports

[The following is an exact transcript of this podcast.]

“We’re on the verge of finding out how frequently habitable planets occur in the universe.” That was astronomer Alan Boss at the AAAS meeting on February 14th. “And I think we’re going to find out that that number is very close to one.” Meaning that each solar-type star is probably orbited by, on average, one Earth-type planet. So how many habitable planets might be out there?

“10 to the 11th in our galaxy and then there are something like 10 to the 11th galaxies. We’re up to about 10 to the 22 Earths, plus or minus a few.

“You don’t have to just believe that this speculation is going to be correct or not. NASA will be launching the Kepler space mission, and Kepler’s entire purpose is to count how many Earths there are around a population of stars in the constellation Cygnus.” Kepler launches on March 5th.

“Then about three or four years from now, there’ll be a press conference at NASA headquarters, and Bill Borucki, the Kepler PI will stand up and tell us just how frequently Earths occur. And once we know that we’ll know how to take the next steps in the search for living planets, and some of that work will involve not only telling if the planets are habitable, but actually searching for signatures in their atmospheres if they could be inhabited, as well.”

—Steve Mirsky 

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