Alpha Centauri: How Habitable Is Our Nearest Solar System?

There are lots of reasons why an alien planet may not be quite as nice, at least in the eyes of us spoiled Earthlings. Perhaps its surface temperature is hundreds of degrees and covered in molten rock. Perhaps its atmosphere is entirely poisonous carbon monoxide. Or perhaps it's bombarded by a steady stream of X-rays.

X-rays have their uses, but without a planetary version of the lead apron that protects the rest of your body during a dental exam, these stellar emissions could prove deadly for any form of life as we know it trying to make its way in the world.

And that's been a bit of a concern for scientists with their eye on the solar system nearest ours, Alpha Centauri.

But according to new research presented at the annual conference of the American Astronomical Society this week, planets orbiting the two main stars in that solar system should receive a reasonably tolerable amount of X-ray radiation.

"This is very good news for Alpha Cen AB in terms of the ability of possible life on any of their planets to survive radiation bouts from the stars," Tom Ayres, an astrophysicist at the University of Colorado Boulder, said in a press release. "Chandra [telescope observations] shows us that life should have a fighting chance on planets around either of these stars."

That solar system contains three stars and at least one planet, and if humans are going to send probes to any neighboring region, Alpha Centauri is definitely the place to start. There's talk of a NASA mission to do just that launching in 2069, and it's the destination for the privately funded Breakthrough Starshot probe as well.

An artist's depiction of what it might look like to stand on the surface of Proxima b, around our solar system's nearest neighboring star. M. Kornmesser/ESO/AFP/Getty Images

But there are some questions we can answer without needing to send robots all the way out there, and the X-ray question is one of them. The team used data gathered by the Chandra Observatory, a space telescope tuned to X-rays, to estimate the amount of radiation a planet around these stars might receive.

Their calculations confirmed worries that Proxima Centauri produces far too many X-rays to be comfortable—a planet here might get a radiation dose 500 times stronger than on Earth, and 100 times that during a serious flare.

But any planets that exist around Alpha Centauri A and Alpha Centauri B should be much better off, receiving at most about five times the radiation as Earth and its neighbors. So that's one more worry off the list—now if only we could find planets in the first place.