Cutaway view of the possible internal structure of Callisto. The surface of the satellite is a mosaic of images obtained in 1979 by NASA's Voyager spacecraft. The interior characteristics are inferred from gravity field and magnetic field measurements by NASA's Galileo spacecraft. Callisto's radius is 2403 km, larger than our Moon's radius. Callisto's interior is shown as a relatively uniform mixture of comparable amounts of ice and rock. The surface layer of Callisto is shown as white to indicate that it may differ from the underlying ice/rock layer in a variety of ways including, for example, the percentage of rock it contains.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/galileo/sepo.