Uranus is the only planet whose equator is nearly at a right angle to its orbit, with a tilt of 97.77 degrees – possibly the result of a collision with an Earth

Uranus is the only planet whose equator is nearly at a right angle to its orbit, with a tilt of 97.77 degrees – possibly the result of a collision with an Earth-sized object long ago. This unique tilt causes the most extreme seasons in the solar system. For nearly a quarter of each Uranian year, the Sun shines directly over each pole, plunging the other half of the planet into a 21-year-long, dark winter. Uranus is also one of just two planets that rotate in the opposite direction than most of the planets (Venus is the other one), from east to west. https://solarsystem.nasa.gov/planets/uranus/in-depth/ https://solarsystem.nasa.gov/planets/uranus/in-depth/