Some experts believe that Uranus was once like all the other planets. That is, its axis was perpendicular to the plane of the solar system. If so, something had to shift the large planet. A giant asteroid might have passed close to Uranus. Its gravity could have tipped Uranus on its side. The asteroid could have slammed into the planet, flipping it over.
Another theory also explains how Uranus got its many moons. Early in its history Uranus may have had only one large moon. The moon orbited Uranus in the direction
