"Voyager 2" passed Io on 9 July 1979 at a distance of . Though it did not approach nearly as close as "Voyager 1", comparisons between images taken by the two spacecraft showed several surface changes that had occurred in the four months between the encounters. In addition, observations of Io as a crescent as "Voyager 2" departed the Jovian system revealed that seven of the nine plumes observed in March were still active in July 1979, with only the volcano Pele shutting down between flybys.