Like Jupiter, Saturn is about 75% hydrogen and 25% helium
with traces of water, methane, ammonia and "rock", similar to the composition of the primordial Solar Nebula from which
the solar system was formed. Saturn's interior is similar to Jupiter's consisting of a rocky core, a liquid metallic hydrogen
layer and a molecular hydrogen layer. Traces of various ices are also present. Saturn's interior is hot it is 12000 K at the
core and Saturn radiates more energy into space than it receives from the Sun. Most of the extra energy is generated by the
kevin-helmholtz mechanicism as in Jupiter. But this may not be sufficient to explain Saturn's luminosity; some additional
mechanism may be at work, perhaps the "raining out" of helium deep in Saturn's interior.