Saturn is 120,000 kilometers across and is the second largest planet in the solar system. This 3-D view was constructed from two Voyager 2 images taken several weeks apart in 1981. It allows us to view the planet and rings as three-dimensional objects, but was obtained too far from Saturn to reveal details of its outer cloud deck and ring system. The low density of Saturn indicates that it is primarily composed of gaseous and liquid hydrogen and helium, and is similar in composition to our Sun. The density of Saturn is low enough that it would float in water. Most of the clouds we see are probably composed of ammonia-ice crystals. Saturn's famous ring system is actually comprised of billions of icy particles ranging in size from dust particles to house-sized boulders. The main rings form a flat gravitationally controlled annular disk only a few kilometers thick and extending roughly 140,000 kilometers from the cloud tops.
Voyager 2 images.