Volcano Euboea Fluctus On Io . ... Credit Copyright: The Galileo Project , JPL , NASA Explanation: Jupiter 's moon Io is turning out to be our Solar System 's geologic powerhouse. ... The black and white photograph on the upper left was taken by the Voyager 1 spacecraft when it flew by in 1979, the upper right and lower left photographs were taken in 1996 by the Galileo spacecraft , while the lower right photograph is a color image taken by Voyager 2, also in 1979. ... NASA Official: Jay Norris. ...