Look up into the skies of the Southern Hemisphere. One of the brightest stars you’ll see is Alpha Centauri. But it’s actually a triple star, with two very sun-like stars – called “A” and “B” – orbiting quite close to one another… …plus a more distant red dwarf named Proxima Centauri. At 4.3 light-years, they are the closest stars to us. And for more than a century, astronomers have tried to determine if any planets might call this system home. Now, a team of European researchers has detected what they believe is a planet – just slightly more massive than Earth – orbiting very close to Alpha Centauri B, which is a bit smaller and dimmer than our Sun, though quite a lot like it many other ways Observations conducted over four years by the HARPS instrument, attached to a mountaintop telescope in Chile, indicate a tiny wobble in the star that corresponds to a small rocky world – much closer in than our planet Mercury – looping around the star once every 3.2 days. The newly proposed planet orbits only 6 million kilometers from its parent star. And that star’s companion, Alpha Centauri A, would be very, very bright in the planet’s skies – if there were anyone there to see it. It’s impossible imagine how anything we’d recognize as life could exist that close to the thermonuclear fires of a star. But this detection is another step towards the discovery of a truly Earth-like planet in orbit around a truly Sun-like star. And the longer astronomers can study any star, the more likely it becomes that Earth-sized planets in Earth-sized orbits will be revealed. For SPACE.com, I’m Dave Brody