This graphic illustrates the interior of Saturn's moon Enceladus. It shows warm, low-density material rising to the surface from within, in its icy shell (yellow) and/or its rocky core (red). A NASA-funded study says Enceladus might have rolled or rotated itself to place this area of low density at the south pole. This finding is in the June 1, 2006, issue of the journal Nature.
This graphic uses parts of visible-light images taken by the Cassini spacecraft camera that have been modified for the purpose of showing the interior structure. Cassini's cameras captured a giant plume blasting icy particles into space.