A team of astronomers said today that they've discovered the first solid example of a planet outside our solar system that could sustain life.
The planet, Gliese (pronounced "GLEE-zuh") 581g, orbits a star about 20 light-years away from Earth and is just the right distance from the star to enjoy temperatures that are hospitable to water in liquid form--and that are thus, researchers said, hospitable to life.
"Our findings offer a very compelling case for a potentially habitable planet," Steven Vogt, professor of astronomy and astrophysics at the University of California at Santa Cruz and one of the leaders of the research team, said in a statement.
The team, made up of astronomers from UC Santa Cruz and the Carnegie Institution of Washington, published its findings in the Astrophysical Journal and online.
To discover Gliese 581g, researchers spent 11 years working with the HIRES spectrometer on the Keck I Telescope at the W. M. Keck Observatory in Hawaii. The spectrometer can pick up wobbles in a star's motion caused by passing planets, and can thus reveal the presence of the planets themselves.
This and other techniques have been used in recent years to discover the existence of numerous Earth-size exoplanets, or planets that are extrasolar--that is, outside our solar system. Gliese 581g is the first such planet, however, that would seem to provide the right conditions for the survival of organisms.
Such existence, though, is by no means certain. If the atmosphere on Gliese 581 "was all carbon dioxide, like Venus, it would be pretty hot," Sara Seager, a planetary astronomer at the Massachusetts Institute of Technology, told The New York Times. Seager said she was skeptical: "Everyone is so primed to say, 'here's the next place we're going to find life,' but this isn't a good planet for follow-up."
Vogt is more than optimistic. At a news conference in Washington, the Times reported, he said he believes that the "chances of life on this planet are almost 100 percent."
A video featuring a discussion with Vogt and Paul Butler of the Carnegie Institution, can be seen here.