Earth-sized planet found in Alpha Centauri by European astronomers using HARPS telescope

By on Oct 17, 2012 in Astronomy, Science Comments

European astronomers announced on Tuesday, October 16, 2012 their discovery of an Earth-sized planet in Alpha Centauri, the star system closest to our plant. The said planet was reportedly only 4.3 light years away from Earth, and was detected using a High Accuracy Radial Velocity Planet Searcher (HARPS) telescope.

According to a report by European Southern Observatory (ESO) on its official website that day, the unnamed planet was discovered by the astronomers using the 3.6-metre telescope HARPS instrument at ESO‘s La Silla Observatory in Chile. Search of such kind of planets was said to be going on since the nineteenth century.

Alpha Centauri is known to be a system composed of of two stars (Alpha Centauri A and B) similar to the Sun and are orbiting close to each other; and a faint red component known as Proxima Centauri, which is slightly closer to Earth than A or B. Alpha Centauri B is a bit smaller and less bright than the Sun.

As noted in the report, the European team found the planet “by picking up the tiny wobbles in the motion of the star Alpha Centauri B created by the gravitational pull of the orbiting planet.” The full report can be found at journal Nature this Wednesday, October 17 titled ‘An Earth mass planet orbiting Alpha Centauri B.’

“Our observations extended over more than four years using the HARPS instrument and have revealed a tiny, but real, signal from a planet orbiting Alpha Centauri B every 3.2 days. It’s an extraordinary discovery and it has pushed our technique to the limit!” Xavier Dumusque, lead author of the report told the paper.

“This is the first planet with a mass similar to Earth ever found around a star like the Sun. Its orbit is very close to its star and it must be much too hot for life as we know it.” Stéphane Udry of the Geneva Observatory, a co-author of the report and team member, was quoted as saying.

Earth sized planet artist impression
Artist’s impression showing the Earth-sized planet orbiting the star Alpha Centauri B
Image Credit: ESO/L. Calçada/N. Risinger (

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