The first ever planet outside the solar system that may be able to support human life had been discovered by astronomers.
It is in the middle of the Gliese 581 star's habitable zone, meaning that temperatures on its surface are just right for life to develop.
Gliese 581 has been under study for more than a decade through the Keck telescope in Hawaii by scientists.
Gliese 581 g or Gl 581 g is one of at least six extrasolar planets found around Gliese 581, an M3V red dwarf star approximately 20.5 light-years away from Earth in the constellation of Libra.
The planet lies near the middle of the Goldilocks zone, or habitable zone of its parent star, and the presence of liquid water is considered a strong possibility.The discovery of Gliese 581 g was announced in September 2010, and is believed to be the first Goldilocks planet ever found, the most Earth-like planet, and the best exoplanet candidate with the potential for harboring life found to date.
The planet was detected using radial velocity measurements combining the data from the HIRES instrument of the Keck 1 telescope and the HARPS instrument of ESO's 3.6m telescope at La Silla Observatory. The planet is believed to have a mass of three to four times that of the Earth and an orbital period of just under 37 days.
Steven Vogt, the co-discoverer, unofficially named the planet "Zarmina", after his wife.
Gliese 581 g is tidally locked to its star, just as our moon is to the Earth; the length of Gliese 581g's day precisely matches the length of its year. With one side of the planet always facing the star, continuous Earth-like temperatures are imaginable in the area between the bright and the dark side. 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. Researchers have estimated that the average surface temperature of the planet is between −31 to −12 degrees Celsius (−24 and 10 degrees Fahrenheit).
In an interview, co-discover Steven Vogt claimed "the chances for life on this planet are almost 100 percent.” However, he said this on a strictly personal basis, stating that he was an astronomer and not a biologist.