Saturn's interior. Computer artwork showing the interior structure of the planet Saturn. Usually,Saturn and Jupiter are known as gas giants,but they are not made entirely of gas. Saturn is composed of 96% hydrogen,3% helium and 1% other elements,but these are just gaseous in the atmosphere (beige),which is about 1000 km thick. Below the atmosphere is a layer of liquid hydrogen and helium about 30,000 km thick (light blue),located above another layer of metallic hydrogen (dark blue) about 15,000 km thick. There is thought to be a rocky core (sphere,centre),with a radius of about 12,000 km,at the centre of the planet |