Like its big brothers Saturn and Jupiter, Uranus is a gas giant: 84% hydrogen, 14% helium, and 2% other lightweight stuff.

Even to the Voyager spacecraft, Neptune looked like a featureless disk, because the compounds (ammonia, ammonium hydrosulfide, water) that form colorful clouds (and, therefore, surface features) on Jupiter and Saturn are all frozen solid on Uranus.

But Uranus does have clouds of its own; they're made of methane. And it's that trace amount of methane that gives the planet its blue-green color. A smoggy haze covers the whole globe and may be a little like what we see on Saturn's moon Titan.

Uranus is also surrounded by a system of thin, dark rings made up of carbon compounds. These rings are much less reflective than Saturn's rings.