Composition 

Of all the planets in the solar system, Saturn holds first place in having the lowest density. Its specific gravity of 0.7 is less than water (by 30%), meaning that it would float on the surface of a large enough ocean!

Saturn's atmosphere is mainly hydrogen (75%) with much smaller amounts of helium (25%), with traces of methane, ammonia and rock. The solid material is probably very similar to the material found in the nebula which that formed our solar system.

The interior of Saturn is made up of several distinct layers. The innermost area has a rocky core, much like in Jupiter's, and a layer consisting of metallic liquid hydrogen. The hydrogen enters a liquid-metallic state because at great depths in the planet, massive pressure exerted on the gas strips electrons off the hydrogen atoms and leaves the hydrogen only with protons. In addition to the planet's rocky core and layer of compressed hydrogen, small amounts of various ices can also be found.

The interior temperature of Saturn is hot, with a reading of 12,000 Kelvin at the core. Much like other gas planets, Saturn radiates more energy into space than it receives from solar input. As on Jupiter, it is important to realize that the internal heat is NOT the result of a nuclear reaction taking place at the core (like a star), but rather, the effect of the Kelvin-Helmholtz mechanism.

The surface of Saturn has a yellowish luminous surface, an effect not yet completely understood, but possibly the result of some kind of mechanism involving helium.