Proxima Centauri: Our Closest Cosmic Neighbor May Have an Entire Solar System We Never Knew About

A sketch of what the solar system around Proxima Centauri might look like. ESO/M. Kornmesser

Just last year, scientists announced they had spotted a planet orbiting the star nearest our sun, Proxima Centauri. Today, they're fleshing out the neighborhood with the announcement that they've found a ring of cold dust circling the star. That may not sound particularly impressive, but it's actually a big deal, because it suggests there might be other planets waiting to be found—perhaps even a whole solar system.

The discovery is described in a new paper accepted for publication in The Astrophysical Journal Letters. "It's the first indication of the presence of an elaborate planetary system, and not just a single planet, around the star closest to our sun," lead author Guillem Anglada, an astronomer at the Institute of Astrophysics of Andalusia in Spain, said in a press release. "This result suggests that Proxima Centauri may have a multiple planet system with a rich history of interactions that resulted in the formation of a dust belt."

That's because all planets, including Earth, are formed from clumps of dust sticking together, meaning modern dust is simply leftover material that didn't quite attach to a promising clump or the result of one of those clumps being destroyed. (When astronomers say dust, they mean rock and ice that's anywhere from a tiny fraction of an inch to miles across.)

That would make it similar to our solar system's Kuiper Belt, which circles past Neptune and Pluto. Astronomers are still cracking this ring's secrets as well, and New Horizons, an unmanned spacecraft, will be visiting an object in it for the first time on January 1, 2019.

The scientists think the Proxima Centauri dust surrounds the star at between one and four times Earth's distance from the sun. But the star is much smaller and fainter than our sun, so they estimate the dust is almost minus-400 degrees Fahrenheit. There's likely about one hundredth the amount of material in that ring as there is in Earth. A second possible ring may echo it ten times further out, although the scientists are less confident about that formation because the signal is much fainter.

Astronomers believe Proxima b is about 1.3 times as large as Earth, tucked in the belt around Proxima Centauri that would allow liquid water to remain on its surface and with one side permanently turned to the star.

NASA doesn't currently have any plans to visit the Proxima Centauri neighborhood, which is a little more than four light-years away from our solar system. (Though Breakthrough Starshot, research funded by venture capitalist Yuri Milner, is dedicated to creating a galactic sailboat to fly there.) Fortunately, with an army of telescopes here on Earth, we don't necessarily need to send a spacecraft—especially not now that we know there's dust it might need to avoid for safety's sake.