Io's Volcanoes: Not Fueled by a Massive Magma Ocean After All

For over 40 years, scientists have been puzzled by Io's extreme volcanic activity. This tiny moon, discovered by Galileo in 1610, is the most volcanically active body in our solar system. But what fuels its 400 active volcanoes? New data from NASA's Juno mission has revealed that Io's volcanoes aren't fed by a single, massive magma ocean. Instead, they're likely fueled by individual chambers of hot magma. This finding, published in Nature, came from Juno's close flybys of Io in 2023 and 2024. During these maneuvers, Juno measured Io's gravity to understand its interior better.The moon's extreme tidal flexing, caused by Jupiter's gravitational pull, generates intense heat. This heat melts parts of Io's interior. If there was a global magma ocean, Io's tidal deformation would be much larger. But Juno's data showed something different. It points to individual magma chambers, not a global magma ocean. This discovery isn't just about Io. It could change how we understand other moons and even exoplanets. It's a reminder that there's still much to learn about our solar system and beyond.