Uranus, computer artwork. Uranus is the seventh planet from the Sun. It has a diameter of four times that of Earth and a volume of 64 Earths. It is a gas giant with an atmosphere of mostly hydrogen and helium, but much of the planet is solid rock and ice below the atmosphere. It has a ring system, and is shown tipped on its side. This is probably due to a big impact event in its early history. The temperature observed in its upper atmosphere is a freezing minus 193 degrees Celsius.