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The closest exoplanet to Earth might have a vast ocean, and even life

Published Sep 17th, 2018 4:01PM EDT
proxima centauri b
Image: Carnegie

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Peering at distant planets is a tricky business for astronomers. There’s plenty that they can assume about planets based on what they look like from afar, but it’s still largely a guessing game. If a planet is the right distance from its star, and has the right size, scientists can dream of life on its surface, but we really can’t say for sure unless we were to visit.

Proxima Centauri b, thought to be the closest exoplanet to Earth, is one such planet, and new computer models are telling scientists that not only is the planet habitable, but it might host a vast ocean that could be perfect for life to take root. As Live Science reports, a new paper published in the journal Astrobiology is a tantalizing glimpse at the far-off world.

Proxima Centauri b, which orbits the nearby star Proxima Centauri, has been the subject of many investigations and observations in the past. It’s a little over four light years away, which is a mere stone’s throw in galactic terms. The planet’s host star is small and much cooler than our Sun, and as a result the habitable zone is quite close to the star itself. Proxima Centauri b is right in that zone, orbiting its star once every every 11 days.

Astronomers have long thought that Proxima Centauri b might be a great candidate for the search for extraterrestrial life, but some past studies have shown that the planet’s proximity to its star might cause problems. Earlier this year, researchers discovered that the planet is getting blasted by stellar flares coming from the small star, and the worry is that those events are too intense for life to endure.

This newest round of research suggests that the planet, which is likely tidally locked and always faces its star with the same side rather than rotating as it orbits, could host a “dynamic ocean” which actually circulates vast amounts of water between its dark and light sides. This would of course be the best case scenario for life, and the climate models show that it’s possible, but it’s far from a sure thing.

The biggest worry for scientists who dream of Proxima Centauri b hosting life is that the tidal lock has resulted in a frozen ocean on the dark side and a boiling hot one on the day side. If this is indeed the case, only a thin ribbon of temperate ocean might be present around the edges of the transition zone. However, if the ocean can regulate its own temperature with currents that circulate water from one side to the other, it might be a life-rich water world.