Ganymede?s magnetosphere makes a big impression on Jupiter?s auroral lightshows

Studies of features in Jupiter?s spectacular and rapidly changing aurora have given new insights into the complex electromagnetic interactions between the giant planet and two of its innermost moons.
As Ganymede and Io orbit Jupiter, they interact with regions of plasma and generate electromagnetic waves that are projected along Jupiter?s magnetic field lines towards Jupiter?s poles [...]

Full story at http://spacefellowship.com/2009/09/17/ganymedes-magnetosphere-makes-a-big-impression-on-jupiters-auroral-lightshows/