Eruption on Io. Coloured Hubble Space Telescope image of Io, a moon of Jupiter, with a volcanic plume (fuzzy patch at Io's lower left edge). The plume of material is coming from the Pele volcano. The plume is 400 kilometres high; the gas and dust in it left Pele at a speed of 3200 kilometres per hour. Pele is one of Io's most powerful volcanoes, but this was the first time that a volcanic plume from it had been seen by a telescope from Earth. Part of Jupiter's surface forms the background. This contrast-enhanced image was taken by combining light at violet and ultraviolet wavelengths on 2 July 1996.