Most planets spin roughly upright as they orbit the Sun - Earth, for example, tilts only 23.5° from vertical, which is what gives us our seasons. Uranus, the ice giant out past Saturn, didn’t get the memo. It’s tipped 98° on its side. Basically, it lies down and rolls around the Sun like a ball.
The sideways rotation does very strange things to its weather and its seasons. Each Uranus pole gets one continuous “day” lasting about 42 Earth years, followed by 42 years of total darkness. When one pole is pointing at the Sun, the other is freezing in a multi-decade night.
Astronomers think Uranus wasn’t always this way. The most likely explanation is that, billions of years ago, it got smashed by another planet-sized object. The impact would have knocked the entire planet on its side. It’s been rolling that way ever since.
