Grab A Surfboard, Our Nearest Exoplanet Proxima B Could Be A Waterworld

Earlier this year, the European Southern Observatory discovered Proxima b, an exoplanet orbiting red dwarf star Proxima Centauri, our closest neighbor 4.2 light years away. The planet is orbiting its star at a distance that could sustain liquid water on its surface, and a new study suggests the planet could be entirely covered by a single ocean. Dibs. We call dibs. Hopefully the high stellar wind pressure there doesn’t make it like the water-covered planet in Interstellar (pictured above) with constant tidal waves. Even so, we still called dibs, and we’re going to Ono Ozaki those sick waves on our boards, brah.

Anyway, a team led by researchers at the Marseille Astrophysics Laboratory estimated [.pdf] different possible compositions for the exoplanet based on what we know so far. We don’t know the radius of the planet, which is where the researchers’ estimates come in. We do know that Proxima b’s mass is 1.3 times that of Earth and it orbits extremely close to its star (one tenth the distance between the Sun and Mercury), with an 11.3 day orbit. This is normal for a possibly-habitable planet orbiting a red dwarf, due to the much lower luminosity of the red dwarf.

The researchers estimated the radius of Proxima b to be between 0.94 and 1.4 times the Earth’s radius. The smaller radius would likely mean a dense metal-cored planet similar to Mercury which may have no water (boooooo). The larger radius would be a planet that could be up to 50% water, meaning a surface covered in a single liquid ocean up to 124 miles (200 km) deep, as well as the possibility of a thin gas atmosphere.

NASA released an artist’s rendering of what the sky might look like there, with a red-tinted star that appears three times larger than our Sun:

It should be noted Proxima b does not have a sunset. It’s tidally locked, meaning one side always faces its star. This also means the planet may be at a habitable temperature in only one ring of land near the edge of its sunny side, although more research will need to be done to estimate surface temperature, exact radius, actual amount of water present, and core composition.

I realize the headline told you to grab a surfboard, but full disclosure: Don’t plan the trip yet. Host star Proxima Centauri is 4.2 light years away. Based on similar estimates for neighboring star Alpha Centauri, our current technologies would require about 39,000 years to travel the 4.2 light years to Proxima b, so we’re not going yet. Oh well, we still get to see Game Of Thrones 4.2 years sooner than they do. Oh man, they’re going to hate Ramsay Bolton so much.

(Via arXiv [.pdf], Next Big Future, NASA, and Ars Technica)