Voyager: The Interstellar Mission Selected Images From the Planetary Tour Jupiter - 1979 The greatest surprise revealed by the mission at Jupiter was probably the discovery of active volcanism on the moon Io. Top image: View of Jupiter and the moons Io (left) and Europa. The planet's great red spot can be seen behind Io. Bottom images: Volcanic eruption on Io, the moon Europa and a view from Jupiter's dark side. The two yellow lines are part of the planet's faint ring system. Go to next slide>> 1 2 3 4 5 6   Jet Propulsion Laboratory    California Institute of Technology   + Image index