Scientists have discovered a planet only slightly larger than Earth in orbit around Alpha Centauri, only 4.37 light years from Earth (only Proxima Centauri is closer). The planet, which was discovered based on fluctuations in the star’s movement, orbits closer to its primary than Mercury does and completes an orbit every three days. The discovery was made using data from La Silla Observatory in Chile and will be officially announced in Nature on October 17.
Astronomers have discovered the most hospitable exoplanet yet found orbiting the star Gliese 581, about 20 light years from Earth. The new planet has been named Gliese 581g, one of two additional planets discovered orbiting Gliese 581, brings that star’s system to six planets. Gliese 581g has a mass between 3 and 4 times that of Earth and orbits in the middle of the star’s habitable zone. The planet is believed to be tidally locked to its primary.