Astronomers have detected an Earth-like exoplanet that may have just the right kind of conditions to support life.
Gliese 581g lies some 20 light-years away in its star's "Goldilocks zone" - a region surface temperatures would allow the presence of liquid water.
Scientists say that the newly found world could also potentially have an atmosphere.
Their findings, made with the Keck telescope in Hawaii, appear in the Astrophysical Journal.
The researchers, from the University of California at Santa Cruz (UCSC) and the Carnegie Institution of Washington, have been studying the movement of the planet's parent star, a red dwarf called Gliese 581, for 11 years.
Their observations have revealed a number of exoplanets spinning around the star.
Possibility of lifeRecently they discovered two new alien worlds, so together with the previous findings, this brings the number of planets orbiting Gliese 581 to six.
But the most important new revelation is that one of those worlds might be the most Earth-like planet yet identified.
"Our findings offer a very compelling case for a potentially habitable planet," said Steven Vogt, an astronomer at UCSC.
"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 581g has a mass about three to four times that of Earth. It orbits its sun in 37 days and is thought to be a rocky world. It has enough gravity to possibly have an atmosphere.
BBC News
