We know that the distant planet Uranus spins sideways, but it still has secrets Discovered less than 300 years ago, and so far away that only one spacecraft has made the trip, humans have lots of questions about the blue-green planet. Learn about Uranus' discovery, what it would be like to visit, and what scientists still want to know. Vivid photos and illustrations, scientist spotlights, and sidebars help unlock the secrets of the ice giant Uranus."