Gliese 581d is an exoplanet located about 20.3 light-years away in the constellation Libra. It orbits the star Gliese 581, which is a red dwarf. Discovered in 2007, Gliese 581d is notable for being within the star's habitable zone, where conditions might allow for liquid water to exist. The planet has a mass at least 7 times that of Earth, suggesting it could be a rocky planet. Its surface temperature and atmospheric conditions are still uncertain, but its position in the habitable zone makes it a candidate for further study in the search for extraterrestrial life.