Io in Jupiter's magnetic field

Simplified view of the magnetic environment around Jupiter and its moon Io. Io, the innermost of the four large moons, is illustrated with vertical magnetic field lines connecting to Jupiter. Io is a volcanic moon, and its thin sulphur dioxide atmosphere generates an ionized plasma torus around Jupiter, seen as the hazy yellow ring. Io's volcanoes release around one tonne of sulphur dioxide every second. These become ionised and picked up by Jupiter’s fast-rotating magnetic field.