Earth-sized planet found orbiting nearest star
October 17, 2012 European astronomers on Wednesday reported they had detected a planet with about the mass of Earth which orbits the closest star to the Sun.
The observation breaks new ground in the hunt for exoplanets — worlds that exist in other solar systems — although the planet itself is not “another Earth” as it is located in a scorchingly hot zone.
The planet swings close to the star Alpha Centauri B, one of a triple star system that is 4.3 light years away, which in cosmic terms is just next door to us.
The find was made thanks to a telltale wobble in the star’s motion, tugged by the gravitational pull of the passing planet.
The signal is “tiny but real,” said Xavier Dumusque of the Geneva Observatory in Switzerland. “It’s an extraordinary discovery and it has pushed our technique to the limit.”
The transiting planet makes the star move back and forth, in relation to Earth, by less than two kilometres (one mile) per hour, about the speed of a baby crawling.
The minute motion was detected using an instrument called HARPS, for high-precision spectrograph, installed on the European Southern Observatory (ESO) at La Silla, in the depths of the Atacama desert in Chile.
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