Every Star Could Have at Least One Planet That Could Support Liquid Water

[n2doc]

Astronomers worldwide agree: there's a heck of a lot of planets out there. Thanks to tools like the Kepler Space Telescope, scientists have been discovering hundreds of new planets each year, and many believe it's only a matter of time until we find one very similar to our own earth. The big question now is, just how common are planets, and how many of them can we expect to look like Earth—or least hold liquid water?

In new study, researchers led by Steffen Jacobsen at the Niels Bohr Institute in Denmark have taken a crack at these questions and come up with some pretty stunning conclusions. By extrapolating on recent planet discoveries found though the Kepler mission, the astronomers have estimated that, on average, every star has between one to three planets nestled into its liquid water-supporting habitable zone. And of those planets, one in six should be rocky like the Earth, Jacobsen says.


"In our galaxy alone, this would mean billions and billions of planets [in their star's habitable zones], with very good chances at finding an Earth twin," Jacobsen says. "But to be clear, these numbers are highly dependent on many assumptions at work here."

How they got those numbers
Since it started staring at the stars in 2009, Kepler has spotted hundreds of new planets and many more planet candidates that could be confirmed in time. It upended what we know and how we think about what's out there in the cosmos.

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http://www.popularmechanics.com/space/a14619/every-star-could-have-at-least-one-planet-that-could-support-liquid-water/

[longship]

1. The error bars are a bit wide, but this is still interesting.

The thing is that Kepler's data has a significant selection bias. It can best detect larger planets orbiting close to their stars. And five years of operation before the reaction wheels failed was not really long enough to find Earth II, a planet of Earth's size in an Earthlike orbit, for which Kepler was designed.

I suspect that all stars below a certain mass have multiple planets. Only the largest, which number very few, have no planets. Also, I suspect that smaller stars, by far the most numerous and long lived stars, may be where life has the best chance. I would guess that Earth got lucky and that life is more likely in less massive rather than Sol or larger stars. That's just because of the numbers.

R&K