Uranus has a solstitial polar-light period lasting roughly 42 Earth years, making it the planet associated with a summer solstice that extends beyond 40 Earth years in popular descriptions. More precisely, the solstice itself is a moment; the long-lasting phenomenon is continuous daylight at one pole during the surrounding season.
Uranus takes about 84 Earth years to orbit the Sun and rotates with an axial tilt of approximately 98 degrees. The planet is therefore almost rolling around the Sun on its side. Around a solstice, one pole points broadly toward the Sun, so that hemisphere experiences continuous sunlight while the opposite pole remains in darkness.
The result is an extreme seasonal cycle: each pole receives about 42 years of daylight followed by about 42 years of darkness. Around the equinoxes, sunlight reaches the equatorial regions and Uranus has a more familiar alternation of day and night across its latitudes.
Jupiter, Saturn and Neptune also have seasons, but none combines such a dramatic axial tilt with an orbital period that produces decades-long polar day. Uranus’s faint rings and unusual orientation are part of the same distinctive planetary story.