Zal Patera on Jupiter's Moon Io . ... Credit Copyright: Galileo Project , SSI , University of Arizona , JPL , NASA . Explanation: The Galileo orbiter 's flyby of Io last November captured an unusual part of Jupiter's volcanic moon. From 26,000 kilometers away, Zal Patera was found to be a cauldron of flowing lava , gaseous vents , and tremendous peaks . ... Shadow lengths indicate that the top of Zal Patera towers nearly 5 kilometers over Io 's molten surface. ... NASA Official: Jay Norris. ...