Richmond Times-Dispatch Weekend
ORBIT, ROTATION AND TILT
Uranus orbits the sun once every 84 Earth years. One day lasts 17 hours and 14 minutes. Like Venus, Uranus rotates east to west, which is the opposite of all the other planets.
THE ‘SIDEWAYS PLANET’
Uranus also has a dramatic orientation. It is the only planet whose equator is nearly at a right angle to its orbit, with a tilt of 97.77°. Its polar regions point toward and away from the sun rather than upward and downward.
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, causing the other half of the planet to have a 21-year-long dark winter.
Since Uranus’ orbit is approximately the length of a human’s entire life, theoretically, a human living on Uranus would experience the four seasons only once, but each for about 21 years.
This tilt also affects the planet’s rings and moons, which orbit in a vertical orientation along the planet’s equator, like a Ferris wheel.