Lynette Cook
A National Science Foundation artist's drawing shows the inner four planets orbiting Gliese 581, a red dwarf star just 20 light-years from Earth. The newly discovered planet, in the foreground, has a 37-day orbit and, like Earth, is distant enough from the star for liquid water to exist.
The possibility of life on other planets has been a staple of science fiction for decades. Now that possibility has taken a step closer to reality as astronomers say they have found a planet orbiting a star a mere 20 light-years away that has the right conditions for life to exist.
EnlargeZina Deretsky/National Science Foundation
All of the planets orbiting Gliese 581 are nearer to it than the Earth is to our sun.
Scientists are calling it the first "Goldilocks" planet, as its temperature seems to be just right to harbor life.
"The planet has to be the right distance from the star so it's not too hot and not too cold that liquid water can exist," says Paul Butler of the Carnegie Institution of Washington. "And then the planet has to have the right surface gravity."
Butler spoke Wednesday afternoon at a news conference organized by the National Science Foundation, the organization that funded Butler's research. Astronomers have found hundreds of planets orbiting other stars in the past decade, but they have all been so far from their suns that any water would be solid ice or so close that liquid water would boil away.
The new planet, called Gliese 581-g, is different. But Butler has no direct evidence that Gliese 581-g actually has water.
"What we know is that this planet exists at the right distance for liquid water, and that it has the right amount of mass to hold onto an atmosphere and to protect its liquid water on the surface," he says. "And of course, any subsequent discussion about life is purely speculative."
But then he couldn't resist speculating: "That being said, on the Earth, anywhere you find liquid water you find life in abundance."
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