Earth sized planet discovered in the Alpha Centauri system, right in our astronomical back yard

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Earth sized planet discovered in the Alpha Centauri system, right in our astronomical back yard

While astronomers have discovered the existence of many, many exoplanets in star systems far, far away, it turns out there’s at least one Earth sized planet in Alpha Centauri, the closest star system to our own. At only 4.5 light years away, it’s close enough that we could reach the planet in just a few short four or five decades.

The Alpha Centauri system actually consists of three separate stars: two big ones (similar in size to our sun) called Alpha Centauri A and B, and a much smaller, redder star called Proxima Centauri.

Using the HARPS instrument on the 3.6-meter telescope at the European Space Agency’s La Silla Observatory in Chile, astronomers were able to measure a minuscule wobble in Alpha Centauri B indicating that a planet was orbiting around it. And by a minuscule wobble, we mean that HARPS was able to detect an entire star changing its movement by about 50 centimeters per second, which is “about the speed of a baby crawling.” Whoa.

This planet, which is just slightly larger than Earth, is unfortunately rather close in to Alpha Centauri B. Like, it orbits in just 3.2 days, meaning that it’s closer to its sun than Mercury is to ours. By a lot. This likely makes it too toasty for any sort of life, but even so, it’s the first planet with a mass similar to Earth ever found around a star like the sun, which is incredibly awesome.

Really, the bigger piece of news here is that exoplanets seem to be just about everywhere. A decade ago, the discovery of any exoplanet at all was pretty big news. Nowadays, they’re so common that we’re only really interested in ones that are either especially weird or especially like Earth. And Alpha Centauri was pretty much the first place anyone ever looked for exoplanets and it took us this long to find one there, suggesting that there are piles more Earth-sized ones that we just haven’t quite had the technology to find yet.

Via