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October 17, 2012

Earth-sized Planet Discovered in Alpha Centauri System

by VOA News

Astronomers in Europe have discovered the first-ever planet with a mass similar to Earth and orbiting a star like the Sun. And, in galactic terms, it’s right next door.

The unnamed planet is in the Alpha Centauri star system, the nearest system to Earth, according to the European Southern Observatory (ESO).

“This result represents a major step towards the detection of a twin Earth in the immediate vicinity of the Sun. We live in exciting times!” said Xavier Dumusque of the Geneva Observatory and Centro de Astrofisica da Universidade do Porto in Portugal in a press release on the discovery.

Despite the excitement, scientists say the new planet’s climate likely would not be nearly as hospitable as Earth.

“Its orbit is very close to its star and it must be much too hot for life as we know it,” said Stéphane Udry of the Geneva Observatory and a co-author of the paper about the discovery.

The newly discovered planet orbits a mere six million kilometers from its star, much closer than Mercury is to the Sun.

Alpha Centauri is the nearest stellar system to the earth’s solar system at only 4.3 light-years, making it one of the brightest objects in the southern skies. It is actually a three-star system made up of two stars similar to the Sun orbiting close to each other, Alpha Centauri A and B, and a more distant and faint red star known as Proxima Centauri.

By detecting tiny wobbles in the motion of Alpha Centauri B, astronomers were able to determine the presence of the planet. The planet’s effect on the star causes it to move no more than 51 centimeters per second, or about the speed of a baby crawling, according to a press release.

In 1995, the same team discovered the first exoplanet around a Sun-like star. There have been more than 800 confirmed discoveries of exoplanets using the same wobble method since then, according to the ESO, but scientists have yet to find a planet of Earth’s size orbiting at a habitable distance from its star.

The planet was detected at ESO’s La Silla Observatory in Chile, and the full results of the finding appears online in the journal Nature on Wednesday.