Uranus is a planet in the Solar System that was named after the Greek god of the sky. This beautiful blue planet is the coldest in our system with a minimum temperature of −224 °C or −371 °F. Many people know that Saturn has rings, but not many have heard of the rings of Uranus! The inner rings of the amazing planet are gray, while the outer rings are blue, as they are composed of particles of ice and dark matter. The Materials Uranus cursor for a mouse!