A BIG BLUE WORLD
The planet's density, 1.3 times that of water, groups Uranus with the other gas giants, such as Jupiter. Its atmosphere is mostly hydrogen and helium, with some methane.
It is believed that Uranus consists of two, or possibly three, layers. At the surface, the mix is gaseous, but increasing temperature and pressure make it behave as a liquid about a third of the way to the center. The remainder ofthe planet is a hot, slushy mixture of water, methane, and ammonia, together with rocky components. It may also have a nickel-iron core. Unlike the other gas-giant planets, Uranus does not seem to have any internal heat source.
In a telescope, Uranus looks pale blue-green because of the methane gas in its atmosphere. Its disk almost always appears featureless, although past observers have noted faint dark bands paralleling its equator.