The new planet is about 50 percent bigger than Earth and about five times more massive. The new â€œsuper-Earthâ€ is called Gliese 581 C, after its star, Gliese 581, a diminutive red dwarf star located 20.5 light-years away that is about one-third as massive as the Sun.Link
Gliese 581 C is the smallest extrasolar planet, or â€œexoplanet,â€ discovered to date. It is located about 15 times closer to its star than Earth is to the Sun; one year on the planet is equal to 13 Earth days. Because red dwarfs, also known as M dwarfs, are about 50 times dimmer than the Sun and much cooler, their planets can orbit much closer to them while still remaining within their habitable zones, the spherical region around a star within which a planetâ€™s temperature can sustain liquid water on its surface.
Computer models predict Gliese 581 C is either a rocky planet like Earth or a waterworld covered entirely by oceans with a mean temperature of between 0 and 40 degrees Celsius [32 to 104 degrees Fahrenheit].