This Voyager 2 picture of Io was taken in ultraviolet light and shows one of the volcanic eruption plumes first photographed.

This Voyager 2 picture of Io was taken in ultraviolet light and shows one of the volcanic eruption plumes first photographed by Voyager 1. (the bright spot on the right limb) The plume is more than 200 kilometers (124 miles) high. The volcano apparently has been erupting since it was observed by Voyager 1 in March, 1979. This suggests that the volcanoes on Io probably are in continuous eruption.