But when Voyager 2 got an up-close look at Uranus in 1986, scientists were able to glean some insights that, while confounding, at least shed some light on a crucial characteristic that seemed to set the planet apart from other giants like Jupiter.

Much of what we understand about Uranus comes from data gathered by NASA's Voyager 2 spacecraft. Thirty-eight years ago, this probe flew by the ice giant, providing humanity with its first close-up glimpse of the seventh planet from the sun.