At first glance, LP 791-18 d seems like a lively place. If new findings from NASA researchers hold up, the Earth-sized exoplanet orbiting a star 90 light-years away from us is teeming with active volcanoes all over its surface. Interesting, sure—but clearly no place for life to thrive, right?
Don’t be so sure. LP 791-18 d, whose discovery was announced in a new study published Wednesday in Nature, might not be a cozy place most for most of us, but the exoplanet, which orbits a small red dwarf star in the southern constellation Crater, may be more habitable than we think. And much of that may actually be due to the fact that it’s covered in hundreds of volcanoes.
LP 791-18 d was found by NASA’s TESS (Transiting Exoplanet Survey Satellite) and the recently retired Spitzer Space Telescope, in combination with data acquired by ground-based observatories around the world. The new paper shows that the planet is probably undergoing the same kind of volcanic outbursts that dot Jupiter’s moon Io, the most volcanically active body in the solar system.
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The planet is tidally locked, which means the same side is constantly facing the star it’s orbiting. One side of the planet is in perpetual daytime, while the other only knows the night. The day side is probably blisteringly hot—and liquid water probably can’t condense on the surface.
But crucially, the volcanic activity that dots the planet means that LP 791-18 d could help build an atmosphere for the entire planet. An atmosphere could help water condense on the night side of the planet. And that means that life of some kind—probably microbial—could perhaps evolve and sustain itself. LP 791-18 d sits precisely in a distance from the star where liquid water could theoretically pool up on a planet.
To be clear, the volcanoes on the planet have not been confirmed, but there is some pretty good reason to believe they exist. LP 791-18 d actually has two sibling planets that also orbit the same star. One of these planets in particular passes close to LP 791-18 d and gravitationally tugs on it, causing slight geological deformations each time. Those deformations are enough to generate internal friction that heat up the planet’s interior and for volcanic activity to burst out of the surface. It’s the same dynamic that explains why Io’s active volcanoes exist.
More work will be needed to confirm what LP 791-18 d really looks like (and hopefully it also gets a name that’s easier to say out loud), but if the findings hold true, it could jump up as one of the most compelling exoplanet discoveries in recent memory.
