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.
Lick–Carnegie Exoplanet Survey
In September 2010, the team announced the discovery of Gliese 581g in orbit within the Gliese 581 planetary system. The observations place the planet in an area where liquid water could exist on the planet's surface, that is, a habitable zone. If confirmed, this would be the first strong case for a potentially habitable Earth-like exoplanet yet discovered. One contributor to the team was Peter Jalowiczor, an amateur astronomer who analyzed some of the data the team released to the public. His work contributed to the discovery of four exoplanets.