Why you can trust us

Engadget has been testing and reviewing consumer tech since 2004. Our stories may include affiliate links; if you buy something through a link, we may earn a commission. Read more about how we evaluate products.

Astronomers identify volcano-covered planet that could have water on its surface

LP 791-18 d is located about 90 light-years away from Earth.

NASA Goddard Space Flight Center / Chris Smith

Astronomers have found a planet they believe is blanketed by active volcanoes. In a study published Tuesday in the journal Nature, a multi-national team of scientists said they discovered an Earth-sized exoplanet they believe may have water on part of its surface. The boringly named LP 791-18 d (sadly, no one thought to call it Mustafar) is located about 90 light-years from Earth in the Crater constellation. LP 791-18 d orbits a red dwarf it is tidally locked to, meaning the planet doesn’t have a day and night cycle like Earth. Instead, one part of LP 791-18 d is constantly scorched by sunlight, while the other is always in darkness.

“The day side would probably be too hot for liquid water to exist on the surface. But the amount of volcanic activity we suspect occurs all over the planet could sustain an atmosphere, which may allow water to condense on the night side,” Björn Benneke, one of the astronomers who studied the planet, told NASA’s Jet Propulsion Laboratory.

The LP 791-18 system contains at least two other planets, called LP 791-18 b and c. The latter is two-and-a-half times larger than Earth and more than seven times its mass. It also affects the orbit of LP 791-18 d, making it travel along an elliptical path around the system’s sun. That path means LP 791-18 d is deformed every time it completes an orbit. “These deformations can create enough internal friction to substantially heat the planet’s interior and produce volcanic activity at its surface,” according to NASA.

“A big question in astrobiology, the field that broadly studies the origins of life on Earth and beyond, is if tectonic or volcanic activity is necessary for life,” study co-author Jessie Christiansen said. “In addition to potentially providing an atmosphere, these processes could churn up materials that would otherwise sink down and get trapped in the crust, including those we think are important for life, like carbon.”

NASA, ESA and CSA already plan to turn the James Webb Space Telescope’s infrared imaging instruments on LP 791-18 c. The team that discovered LP 791-18 d thinks the exoplanet would make for an “exceptional candidate for atmospheric studies by the mission.” Notably, the retired Spitzer Space Telescope helped spot LP 791-18 d before NASA decommissioned it in 2020. This week, the US Space Force awarded a $250,000 grant to explore the feasibility of bringing the telescope out of retirement.