Extraterrestrial liquid water
The Gliese 581 planetary system contains multiple planets that may be candidates for surface water, including Gliese 581c, Gliese 581d, might be warm enough for oceans if a greenhouse effect was operating, and Gliese 581e.
Extraterrestrial liquid water
A planet's orbit in the circumstellar habitable zone is a popular method used to predict its potential for surface water at its surface. Habitable zone theory has put forward several extrasolar candidates for liquid water, though they are highly speculative as a planet's orbit around a star alone does not guarantee that a planet it has liquid water. In addition to its orbit, a planetary mass object must have the potential for sufficient atmospheric pressure to support liquid water and a sufficient supply of hydrogen and oxygen at or near its surface.