A team of scientists has discovered a potentially habitable planet located about 20 light years from Earth.
The paper reports the discovery of two new planets around the nearby red dwarf star Gliese 581. This brings the total number of known planets around this star to six, the most yet discovered in a planetary system other than our own solar system. Like our solar system, the planets around Gliese 581 have nearly circular orbits.
The most interesting of the two new planets is Gliese 581g, with a mass three to four times that of the Earth and an orbital period of just under 37 days. Its mass indicates that it is probably a rocky planet with a definite surface and that it has enough gravity to hold on to an atmosphere, according to Vogt.
Gliese 581, located 20 light years away from Earth in the constellation Libra, has a somewhat checkered history of habitable-planet claims. Two previously detected planets in the system lie at the edges of the habitable zone, one on the hot side (planet c) and one on the cold side (planet d). While some astronomers still think planet d may be habitable if it has a thick atmosphere with a strong greenhouse effect to warm it up, others are skeptical. The newly discovered planet g, however, lies right in the middle of the habitable zone.
Sam Arbesman’s prediction of May 2011 might have been too conservative. And 20 light years…that means we could send a signal there, and if someone of sufficient technological capability is there and listening, we could hear something back within our lifetime. Contact! (thx, jimray)