Uranus orbits almost "on its side" at a tilt of 98 degrees, possibly as a result of a collision with an Earth-size object early in its history. Its moons and rings may be leftover fragments from this impacting body. The tilt gives the planet peculiar seasons, with one pole or the other pointing to
ward the Sun for several decades. Such long cycles of sunlight and darkness heat the polar regions more than the equator. The resulting energy imbalance would explain the 450 mile per hour (720 km/h) winds detected during the Voyager 2 flyby.