Uranus Rolls on Its Side, Trading 42-Year Daylight for Darkness

Uranus sits on its side with a 97.8-degree tilt, rolling around the Sun so each pole endures about 42 years of daylight followed by 42 years of darkness, creating extreme seasons and unusual atmospheric responses that lag behind the sunlight. Voyager 2 remains the only spacecraft to have visited, and while a giant early collision is the leading explanation for the tilt, some theories involve a spin-orbit resonance with a hypothetical Planet Nine; the full story is still debated.