Jupiter’s moons could keep each other warm by raising tidal waves
Gravitational kneading from the mammoth planet is not the satellites’ only source of heat

Gravitational forces from Jupiter’s four largest moons (from left: Io, Europa, Ganymede and Callisto) push and pull on each other’s insides, helping to keep the interiors sloshy, a study suggests.
JPL-Caltech/NASA, DLR