Claim: Uranus's uppermost layer of clouds contains methane.

Uranus is the seventh planet from the Sun . It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System . Uranus is similar in composition to Neptune , and both have different bulk chemical composition from that of the larger gas giants Jupiter and Saturn . For this reason , scientists often classify Uranus and Neptune as `` ice giants '' to distinguish them from the gas giants . Uranus 's atmosphere is similar to Jupiter 's and Saturn 's in its primary composition of hydrogen and helium , but it contains more `` ices '' such as water , ammonia , and methane , along with traces of other hydrocarbons . It is the coldest planetary atmosphere in the Solar System , with a minimum temperature of 49 K , and has a complex , layered cloud structure with water thought to make up the lowest clouds and methane the uppermost layer of clouds . The interior of Uranus is mainly composed of ices and rock .   Uranus is the only planet whose name is derived from a figure from Greek mythology , from the Latinised version of the Greek god of the sky Ouranos . Like the other giant planets , Uranus has a ring system , a magnetosphere , and numerous moons . The Uranian system has a unique configuration among those of the planets because its axis of rotation is tilted sideways , nearly into the plane of its solar orbit . Its north and south poles , therefore , lie where most other planets have their equators . In 1986 , images from Voyager 2 showed Uranus as an almost featureless planet in visible light , without the cloud bands or storms associated with the other giant planets . Observations from Earth have shown seasonal change and increased weather activity as Uranus approached its equinox in 2007 . Wind speeds can reach 250 m/s .