Which planet spins on its side?
Uranus spins on its side, with its axis tilted about 98 degrees. It essentially rolls around the Sun like a ball, so each pole gets about 42 years of continuous sunlight followed by 42 years of darkness.
Most planets spin roughly upright compared to their orbits, though Earth tilts about 23.5 degrees, which causes our seasons. Uranus's extreme tilt means that during its 84-year orbit, one pole points almost directly at the Sun for a long time, then the other.
Scientists think Uranus was knocked over by one or more giant collisions with Earth-sized objects early in the solar system's history. Its rings and moons also orbit around its tilted equator. Uranus also spins in the opposite direction from most planets, technically making its rotation retrograde.
An ice giant
Uranus is a blue-green ice giant, made mostly of water, methane and ammonia over a small rocky core. The methane in its atmosphere absorbs red light, giving it its color. Only one spacecraft, Voyager 2 in 1986, has visited it. NASA has proposed a future mission to orbit Uranus.
Did You Know?
Uranus was the first planet discovered with a telescope, by astronomer William Herschel in 1781.