Jupiter and Saturn are the two largest and fastest spinning planets in the Solar System. They are both made mostly of the gases hydrogen and helium. Jupiter is the largest. It weighs two and a half times as much as all the other planets put together. Its outer layer of gas clouds is about 1,000 km thick. Fierce winds blow these clouds and huge streaks of lightning flash between them. Below the cloud layer the gases get denser and denser until they become liquid.
Saturn is made of less dense gases. It could even float on water! The planet looks beautiful as it is surrounded by rings. The rings aren’t solid. They are probably made of pieces of rock and ice which orbit the planet.
Here we see Jupiter with two of its moons. It has at least 39 moons in total.
This picture is made up of photographs of Saturn and several of its moons.