uranus88Uranus’s Unique Atmosphere. When we talk about Uranus, one of the first things that comes to mind is its unusual atmosphere. This distant ice giant boasts a composition quite different from the more familiar planets like Earth or Mars.Uranus is the seventh planet from the sun, and it is the third-largest planet in the solar system. It has a diameter of 50,724 kilometers and a mass of 8.68 x 10^25 kilograms, making it about