http://www.foxnews.com/scitech/2010...lanet-percent-astronomer-say/?test=latestnews "An Earth-size planet has been spotted orbiting a nearby star at a distance that would makes it not too hot and not too cold -- comfortable enough for life to exist." "If confirmed, the exoplanet, named Gliese 581g, would be the first Earth-like world found residing in a star's habitable zone." "It really is monumental if you accept this as the first Earth-like planet ever found in the star's habitable zone," "The newfound planet joins more than 400 other alien worlds known to date. Most are huge gas giants, though several are just a few times the mass of Earth." "The star is located 20 light-years from Earth in the constellation Libra. One light-year is about 6 trillion miles (10 trillion km)." "Gliese 581g has a mass three to four times Earth's, the researchers estimated. From the mass and size, they said the world is probably a rocky planet with enough gravity to hold onto an atmosphere." "Just as Mercury is locked facing the sun, the planet is tidally locked to its star, so that one side basks in perpetual daylight, while the other side remains in darkness. This locked configuration helps to stabilize the planet's surface climate, Vogt said." "Between blazing heat on the star-facing side and freezing cold on the dark side, the average surface temperature may range from 24 degrees below zero to 10 degrees Fahrenheit (minus 31 to minus 12 degrees Celsius), the researchers said."