Like Earth, Jupiter has auroras that gleam at its poles—a result of the planet’s magnetic field interacting with energetic particles streaming from the Sun. In recent years astronomers have noticed that Ganymede and Io, two of Jupiter’s moons, each add their own personal stamp to the planet’s auroras.
In this ultraviolet image from HST, Jupiter's aurora is visible. Jupiter's larger moons produce electric currents which interact with Jupiter's magnetic field, resulting in emissions that flow through the aurorae as the moons revolve around the planet.