Researchers Find First Planet That Could Support Life

Researchers said Thursday that for the first time they've discovered an extrasolar planet that could harbor life, as it lies squarely in the so-called "habitable zone" of a nearby star.
The planet, dubbed "Gliese 581g," is the sixth known planet found orbiting the red dwarf known as Gliese 581, found within the constellation of Libra. The planet was found by teams at the University of California (UC) Santa Cruz, and the Carnegie Institution of Washington, after nearly a decade of observations using the W. M. Keck Observatory in Hawaii.

If Gliese 581g orbited within our solar system, its nearly circular orbit would place it just outside the orbit of Venus, well within the "habitable zone" where liquid water could be found. The presence of water is usually considered a good sign that life could exist.
Gliese 581g, dubbed a "Goldilocks planet" by co-discoverer R. Paul Butler of the Carnegie Institution of Washington, is tidally locked, meaning that the same face of the planet always is oriented toward the sun, with another residing in perpetual darkness. Life could be found near the terminator, or the intersection of the two regions.
The researchers estimate that the rocky planet has a mass about three to four times of Earth, with an orbit of about 37 days.
"Our findings offer a very compelling case for a potentially habitable planet," said Steven Vogt, professor of astronomy and astrophysics at UC Santa Cruz, in a statement released by NASA. "The fact that we were able to detect this planet so quickly and so nearby tells us that planets like this must be really common."
Gliese 581 already has two previously detected planets that lie at the edges of the habitable zone, one on the hot side (planet c) and one on the cold side (planet d), NASA said.