Composite image showing the interiors of Jupiter, Saturn, Uranus and
Neptune as well as their atmospheres as seen by the Voyager
spacecraft. Information on the internal structure is obtained through
measurements of the departure of the planetary gravitational sphere
from sphericity due to the rapid rotation of the planet. 
Regions in yellow are essentially made of molecular hydrogen. At high
pressures, hydrogen becomes metallic, which is indicated in red. Ices
are shown in blue, rocks are in black. The internal structures are
indicative.