Uranus appears to have been knocked over on its side! It rotates at almost a right angle to the plane of its orbit. And it spins very fast for such a big ball—once every 17 hours. The unusual tilt is very likely the aftermath of a collision with another large body billions of years ago.

So today, as Uranus careens around the sun, one pole will point inward, then the equator, then the other pole, then the equator again. Under these circumstances, trying to figure out what the words "day" and "year" mean on Uranus isn't at all easy!

All this wacky motion gives Uranus highly exaggerated seasons. Planetary geoscientists using the Hubble telescope have detected seasonal storms in the planet's atmosphere.