Astronomers have located a distant, Earth-sized planet that could be covered with more volcanoes than any body in our solar system. The exoplanet, described for the first time Tuesday in the journal Nature, may also have water on its surface, signaling that it might support life.
Called LP 791-18 d, the newly discovered world is roughly 90 light-years away from Earth in the Crater constellation in the Milky Way galaxy. It’s orbiting a dim red dwarf star—which is cooler and smaller than the sun—along with at least two other planets, named LP 791-18 b and c.
Though astronomers haven’t directly observed any eruptions, they say the exoplanet is a “particularly likely candidate” for volcanic activity due to the gravity of its more massive neighbor, LP 791-18 c, says study co-author Ian Crossfield, an astronomer at the University of Kansas, to Reuters’ Will Dunham. This force squeezes and deforms the distant world, producing friction and heat beneath its surface, which could lead to volcanic eruptions. The same phenomenon occurs between Jupiter and its moon Io, the most volcanically active body in our solar system.
Scientists used an array of telescopes and observatories to study the far-off planet, including the now-decommissioned Spitzer Space Telescope and the Transiting Exoplanet Survey Satellite (TESS). Based on their analysis, they suspect LP 791-18 d may be a bit larger than Earth in mass and size—and perhaps even more volcanically active than Io.
We found a planet! It's small enough and passes close enough to another planet in its system that, like Io in our solar system, it could have tidally induced volcanic activity. TIME WILL TELL. Well, mostly #JWST. But ALSO TIME.https://t.co/lPF51lC1sQ— Dr. Jessie Christiansen (@aussiastronomer) May 17, 2023
As LP 791-18 d orbits its red dwarf, the same side always faces the star, a state astronomers describe as being “tidally locked.” As a result, the planet’s star-facing side is likely a desert, where it’s too hot and dry for water to persist. But the amount of suspected volcanic activity suggests the world might have an atmosphere, and if so, water could condense on the cooler side that faces away from the star. Astronomers say a large glacier might exist on the planet’s dark side, per Reuters.
But it’s the in-between areas on the planet’s surface, where the dark and light sides meet, that could really intrigue scientists. In these milder regions, ice from the dark-side glacier may be melting into liquid water. These places could be “a bit like Iceland,” says Björn Benneke, an astronomer at the University of Montreal, to the Toronto Star’s Kevin Jiang. “You [might] have lots of ice, but also volcanic activity underneath.”
Some astrobiologists believe that volcanic or tectonic activity is necessary to support life on planets. That’s because these natural occurrences stir up elements that are important for life, such as carbon, and may also emit gases that help create an atmosphere. This theory is still up for debate, however.
Even so, the evidence of volcanic activity on LP 791-18 d gives astronomers hope that they might “one day find signs of life on another planet,” says study co-author Karen Collins, an astronomer at the Center for Astrophysics, Harvard & Smithsonian, in a statement.
The team believes life is possible on this supposedly volcanic world, because it sits within the so-called habitable zone around its star, also known as the Goldilocks zone. In this region, conditions are just right for liquid water to exist on a planet’s surface.
Researchers have already gotten the green light to study the neighboring planet LP 791-18 c with the James Webb Space Telescope, and they’re hopeful they could use also the high-tech observatory to glean further insights into the newly discovered world.
And, even if it turns out LP 791-18 d does not have any volcanoes or evidence of habitability, astronomers will still be happy to have simply examined a new planet.
“People study Jupiter still, but they don’t do it because they think there are aliens living there,” says Crossfield in a statement. “People study asteroids, just because we can and because we learn new things. Lots of exoplanet science is just about learning interesting things about the universe.”