If you want to find neighbors, you probably start by looking next door, not blocks away. And that’s the strategy astronomers used in looking for neighboring planets. They started by looking around neighboring stars that were close by. In fact, they’ve been looking at the closest star system, Alpha Centauri, for decades.

Alpha Centauri is a bit more than four light-years away. It consists of three stars. Two of them — Alpha Centauri A and B — are close together, and both are fairly similar to the Sun. The third star is far away from the others, but it’s quite small and faint.

That star is known as Proxima Centauri, because it’s closer to Earth than the other two. And there’s pretty clear evidence that it has at least one planet. It’s a rocky world a little heavier than Earth, and it’s in the star’s habitable zone — the region that’s most comfortable for life.

Astronomers thought they’d found a planet around star B, but it turned out to be a glitch in the data.

But they haven’t given up. They’ve increased their efforts this year, in fact, because stars A and B are at their farthest apart as seen from Earth. That makes it a little bit easier to find planets.

Alpha Centauri is the third-brightest star system in the night sky. But it’s so far south that it’s not visible from most of the U.S. From far-southern Texas and Florida, and from Hawaii, it’s low in the south as night falls — a system where we’re still looking for neighbors.

Script by Damond Benningfield

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