This is a schematic of the interior of Jupiter. Click on image for full size version (144K GIF) Image from: NASA

The Giant planets do not have the same layered structure that the terrestrial planets do. Their evolution was quite different than that of the terrestrial planets, and they have less solid material.

Jupiter's interior composition is primarily that of simple molecules such as hydrogen and helium, which are liquids under the high pressure environments found in the interiors of the outer planets, and not solids.

Motions in the interior of Jupiter contribute in a very special way to the development of the powerful and extensive magnetosphere of Jupiter. Heat generated within Jupiter contributes to the unusual motions of the atmosphere.