Polar Night

Polar night is the phenomenon, confined to the areas within the polar circles, in which the Sun stays below the horizon for more than twenty four hours at a stretch. It is the seasonal inverse of the midnight sun. Because sunlight is bent by atmospheric refraction, periods of polar day run slightly longer than periods of polar night, so the regions that experience true polar night are somewhat smaller than those that experience continuous polar day. The polar circles sit at about 66.5 degrees latitude, and because the Arctic and Antarctic tilt toward and away from the Sun in opposite halves of the year, daytime in the Arctic Circle corresponds to nighttime in the Antarctic Circle. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/