Using the European Southern Observatory's 3.6-meter telescope in Chile, astronomer Stephane Udry and his colleagues discovered that a planet about five times as massive as Earth is the smallest and potentially most Earth-like planet outside the solar system. It orbits a small, dim "red dwarf" star called Gliese 581 which lies 20.5 light years away every 13 days. The planet is believed to be habitable because the astronomers calculated that it has a pleasant right-for-liquid-water-existence surface temperature of about 0 to 40° C. LinkTags: