CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Io Rotation Movie

During its 1979 flyby, Voyager 2 observed Io only from a distance. However, the volcanic activity discovered by Voyager 1 months earlier was readily visible. This sequence of nine color images was collected using the Blue, Green and Orange filters from about 1.2 million kilometers. A 2.5 hour period is covered during which Io rotates 7 degrees.

Rotating into view over the limb of Io are the plumes of the volcanoes Amirani (top) and Maui (lower). These plumes are very distinct against the black sky because they are being illuminated from behind. Notice that as Io rotates, the proportion of Io which is sunlit decreases greatly. This changing phase angle is because Io is moving between the spacecraft and the Sun.

This time-lapse movie was produced at JPL by the Image Processing Laboratory in 1985.

The Voyager Project is managed for NASA by the Jet Propulsion Laboratory, Pasadena, Calif.

Acquired: July 1979
  Io Rotation Movie
PIA 02857

Full Size 220x460:
GIF 157 KB
MP4 movie 74 KB