Earth-sized planet found orbiting Alpha Centauri

Well, this is pretty damn exciting: astronomers have confirmed the detection of a planet just 1.13 times the size of Earth orbiting around Alpha Centauri B, which is part of the closest star system to Earth. At just 4.3 light-years away, it's potentially reachable in just a few decades with near-term technology, and now we've got a place to land. Er, sort of.

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.

It's simply a matter of time now until we manage to find a little planet with the ideal combination of size and location and water and everything, that might either be the perfect new home for our species or already home to an alien one.


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