New Horizons continues to send back remarkable images from the Jupiter neighborhood. Here you can see the eruption of the volcano Tvashtar: that pinpoint of light near the north pole of Io. Note the slash of shadow across the plume of gas and vaporized rock. The brightly lit portion is illuminated by the sun; the fainter portion is revealed by reflected light from nearby Jupiter.
Io’s lighter-than-Earth gravity has less of a hold on things at the surface. That plume is about 200 miles high.