Astronomers looking for alien planets have long glanced through their telescopes at the Alpha Centauri system and wondered. Since it is the closest solar system to our own, it is also the nearest possible abode for E.T. beyond our solar system. In fact, communication with aliens from Alpha Centauri would only take only about four years each way, since it is only 4.37 light-years away.


The technology to detect planets in other star systems has not existed until recently, however, and it is especially difficult to detect smaller, rocky planets like Earth. But for the first time, European astronomers studying the faint wobble of Alpha Centauri's stars have struck Space Age gold. They've detected an Earth-sized planet in a foreign solar system, and it's right in our interstellar backyard, reports Nature.


The planet is like Earth in size, but those hoping to find little green men might be disappointed to learn that the similarities pretty much end there. The Centauri planet completes an orbit of Alpha Centauri B, a star only slightly smaller and less bright than our sun, once every 3.2 days. So its years pass by at lightning speed. It is also orbiting just 6 million kilometers away from its star, which is much closer than Mercury is to our sun.


In other words, the new planet is probably a scorching hot, barren wasteland, not suitable for life. The good news, though, is that the planet is not likely to be alone. The finding raises the probability that other rocky siblings, perhaps one orbiting at an Earth-like distance, could soon be detected as well.


"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 lead researcher Xavier Dumusque.


The planet was detected using HARPS (High Accuracy Radial velocity Planet Searcher) on the telescope at the La Silla Observatory in Chile. The HARPS tool, which measures the minute wobble of stars as they are tugged to-and-fro by the gravitational force of orbiting planets, has proven an invaluable tool for detecting worlds outside our solar system. The new discovery, though, is the first planet with a mass similar to Earth ever found around a star like the sun. It's a testament to the advancing precision of the method.


Finding a twin Earth at a suitable distance from Alpha Centauri B would require another leap in sensitivity, since the smaller and more distant a planet is from its star, the more difficult it is to detect. But it's only a matter of time before the technology gets there.


Alpha Centauri would certainly be a thrilling place to live. The Centauri system is actually a spectacular three-star system. Two of the stars, Alpha Centauri A and B, are similar to our sun in size and luminosity. The third star, known as Proxima Centauri, is a red dwarf that is at a greater distance from the other two but actually closer in proximity to our solar system, making it the nearest known star to the sun.


Watch this video to get an idea of what it would be like to travel from Earth to Alpha Centauri:



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Bryan Nelson ( @@brynelson ) writes about everything from environmental problems here on Earth to big questions in space.

Earth-like planet discovered just 4 light years away
A new planet roughly the same size as Earth has been discovered in the nearest solar system to our own.