Winter on Uranus lasts 21 years!

Because it takes Uranus 84 Earth-years to orbit the Sun, each of its seasons lasts for a quarter of this time, or 21 years. A two-decade winter sounds bad to begin with, but if you could live on Uranus I guarantee it would be even more brutal than you realize! This is because, unlike Earth’s axis, which is slightly tilted off vertical (relative to the Sun), the axial tilt of Uranus is nearly perpendicular to the Sun. This means that for two of those four 21-year seasons, one of the poles will NEVER see the Sun! This sort of thing happens on Earth too, but winter near our poles means they get very little sunlight for a few weeks, not none at all for 21 years!
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