Figure 36.25 Surface changes on Io.

These images show dramatic changes on Io's surface during a five-month period. Galileo captured the left frame during its seventh orbit of Jupiter, the right frame during its tenth orbit. A new dark spot, 400 km in diameter (roughly the size of Arizona), surrounds a volcanic center named Pillan Patera. Galileo imaged a 120-km-high plume erupting from this location during its ninth orbit. Pele, which produced the larger plume deposit southwest of Pillan, also appears different than it did during the seventh orbit, perhaps as a result of interaction between the two large plumes. (NASA/JPL)

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