spacetoday.net: Earth-sized planet found at Alpha Centauri

Posted: Wed, Oct 17, 2012, 9:02 AM ET (1302 GMT)
Alpha Centauri Bb illustration (ESO)

Astronomers announced Tuesday they have evidence for a planet the mass of the Earth closely orbiting one of the stars in the Alpha Centauri system, the closest star system to the Sun. A team using a 3.6-meter telescope at the European Southern Observatory (ESO) indirectly found the planet, orbiting Alpha Centauri B, by detecting the wobble gravitationally induced in the star from the orbiting planet. The planet, Alpha Centauri Bb, has a minimum mass slightly larger than the Earth but orbits the star at a distance of only six million kilometers, completing one orbit in 3.2 days. The planet has an estimated surface temperature of 1,200 degrees Celsius, making it inhospitable for life. the planet is the first to be detected orbiting any of the three stars of the Alpha Centauri system, which at less than 4.4 light-years away is the closest system to our own.