 Gliese 581 g has attracted attention because it would be near the middle of the habitable zone of its parent star. That means it could sustain liquid water on its surface and could potentially host life similar to that on Earth (the planet is predicted to have temperatures around − 37 to − 11°C). If it is a rocky planet, favorable atmospheric conditions could permit the presence of liquid water, a necessity for all known life, on its surface. With an estimated mass of 2.2 times Earth's, Gliese 581 g would be considered a Super-Earth and would be the planet closest in mass to Earth known in a habitable zone. This would make it one of the most Earth-like Goldilocks planets found outside the Solar System and one of the exoplanets with the greatest recognized potential for harboring life.
