Astronomers announced the discovery of the closest-ever Earth-sized exoplanet. Orbiting around the sun-like star Alpha Centauri B, the newly discovered planet is part of a three-star system just 4.3 light years away from us. The planet, named Alpha Centauri Bb, isn't a copy of ours though, it orbits at a distance of just 3.6 million miles from its star, and researchers say the planet has a heat-blasted surface that may be covered with molten rock.
Besides being the closest known exoplanet, Alpha Centauri Bb is also unique because it's the first planet with a mass similar to Earth ever found around a sunlike star. The planet is about 13 percent more massive than Earth, and is estimated to have a surface temperature of 1,277°C.
The mere existence of the planet, known as Alpha Centauri Bb, suggests that undiscovered worlds may lurk farther away from its star — perhaps in the habitable zone, that just-right range of distances where liquid water can exist.
"Most of the low-mass planets are in systems of two, three to six or seven planets, out to the habitable zone," study co-author Stephane Udry, of the Geneva Observatory, told reporters today (Oct. 16).
So the discovery "opens really good prospects for detecting planets in the habitable zone in a system that is very close to us," Udry added. "In that sense, this system is a landmark."