European astronomers announced the discovery today of an earth-sized planet orbiting Alpha Centauri B, a star 4.4 light years away. The planet was detected over four years of observation with the High Accuracy Radial velocity Planetary Search spectrometer on the European Southern Oberservatory’s telescope in La Silla, Chile. This world is the least massive exoplanet yet discovered, and it is in our celestial backyard. It orbits only four million miles out from its sun, and in only three of our days, meaning that its surface temperatures would be around 1200 degrees Fahrenheit.
In this artist’s impression, the new exoplanet is depicted orbiting Alpha Centauri B with its bright stellar companion Alpha Centauri A off to the lower left. On the upper right is the light of our sun, as seen from its nearest neighbors. Not pictured is the third sun in the system, Proxima Centauri (image credit: ESO/L. Calçada).