Why is Uranus called the topsy-turvy planet?

Planets spin around their axis while orbiting the sun. In other planets the axis is almost upright but in Uranus, the axis is at right angles to normal which makes it seem as if Uranus is lying on its side. So, at times, Uranus’ poles will be pointing directly at the sun. This makes them hotter than the rest of the planet instead of being colder as is the case of earth.