Using the European Southern Observatory (ESO) 3.6-m telescope the team discovered Gliese 581c and calculated it has 5 times the mass of the Earth, orbits a red dwarf and is already known to harbour a Neptune-mass planet. Gliese 581c’s Sun is smaller and colder than our Sun but since the planet has a much closer orbit than that of the earth (a full orbit or a year on Gliese 581c takes 13 days) it has a very reasonable temperature of between 0 and 40 degrees Celsius (32- 104 degrees Fahrenheit), and if it has water on its surface it would be found in a liquid state.
Gliese 581, is among the 100 closest stars to us, located only 20.5 light-years away in the constellation Libra ("the Scales"). It has a mass of only one third the mass of the Sun. Such red dwarfs are intrinsically at least 50 times fainter than the Sun and are the most common stars in our Galaxy: among the 100 closest stars to the Sun, 80 belong to this class.
TFOT reported several related discoveries in recent years. In 2006 NASA’s Hubble Space Telescope discovered 16 extrasolar planet candidates orbiting a variety of distant stars in the central region of our Milky Way galaxy. Later on that year NASA’s Spitzer Space Telescope made the first measurements of the day and night temperatures of a planet outside our solar system. On December 2006, the COROT (COnvection ROtation and Planetary Transits) space-based telescope was launched from the Baikonur Cosmodrome. COROT will observe more than 120,000 stars and try to detect planets with orbits of 50 days or less in other stellar systems as they pass in front of their parent stars, blocking some of the light.