New map reveals secrets of Io, the solar system’s most volcanic moon

Scientific American interviewed Tracy Gregg about a new map of Jupiter’s moon Io, which is the most volcanic moon in the solar system. The map, which examines 266 volcanic hotspots, suggests that tidal heating on Io is concentrated in its shallower depths, closer to the crust, challenging previous models suggesting deeper heating. The study found that lower latitudes emitted 60% more volcanic heat, indicating that tidal heating may occur within a putty-like upper mantle or a partly/fully molten ocean below the crust. Gregg notes researchers cannot even be sure that the pattern of Io’s volcanic thermal emissions is a reliable proxy for the moon’s heat flow. “Magma will come to the surface where it can, even if that isn’t directly over the melting source,” says Gregg.