Astronomers have found evidence for a volcanic moon orbiting an exoplanet 635 light-years from Earth. No moons have been confirmed to orbit planets outside our solar system, but a sodium cloud hints at the existence of one around exoplanet WASP-49 b.
Moons orbiting planets outside our solar system — also known as exomoons — are hard to detect, as they are too small and too dim to be picked up by telescopes. Astronomers have found multiple candidates for exoplanets with moons, but none have been confirmed.
However, volcanically active exomoons could be detected through the material they spew into space. A similar phenomenon occurs in our solar system, as volcanic activity on Jupiter’s moon Io creates gigantic clouds of volcanic gasses around the planet. These clouds are many times the size of Jupiter, up to 1,000 times the planet’s radius. A similar cloud has now been detected around WASP-49 b.