A red dwarf star which is 20 light-years away had again provided hints that the star hosts the first definitively habitable planet which is outside our Solar System.
The planet Gliese 581d is located at the colder outer edge of the "Goldilocks zone" where the liquid water can be constant.
A study in Astrophysical Journal Letters had suggested that their atmosphere might keep things warm enough for water.
The solar system also hosts another candidate for habitability, unconfirmed by the planet Gliese 581g announced in the year 2010.
But, the existence of that planet was since put into question.
Gliese 581d had been found along with the planet Gliese 581c in 2007.
Gliese 581c had soon been determined to be too close to its host star to withstand water, with a surface temperature beyond 1,000C.
The outlying planet 581d had been first taken to be too cold to contain liquid water.
Gliese 581d's thicker air and dim red light from its host star will make for a murky environment that will be harmful to humans.