What is the polar night?
Polar Night concerns more than 24 hours that occur seasonally in the polar regions of the Earth. Since the Earth's axis is tilted 26 degrees with regard to the elliptics level, there are parts of poles whose rotary path will never be exposed to light. The North and South poles are the darkest regions of all, each of which receives six months of continuous night and six months of continuous day. The depth of the polar night in the polar regions is, when the lowest temperatures on the ground were recorded, 89 degrees Celsius below zero or negative 128 degrees Fahrenheit, measured at Vostok in Antarctica. Without heavy fur, this can lead to death in less than two minutes.
The formal definition of the Arctic and Antarctic Circle is related to the polar night. There is at least one 24 hours of total darkness in the circle, while the darkness lasts less than 24 hours. Some in the north and south are very experienced nights, with a few hours of the sun throughout the day during the winter. Examples include Hammerfest, Norway and Research Stationse in most Antarctica. Being deprived of light to this extent can be a risk factor for depression.
Inverse polar night is called midnight sun or polar day where it is a longer day in the summer. This can do the environment (relatively) warm and permission for long treks above the ice, such as those achieved by Roald Amundsen, the Norwegian polar explorer to the first to achieve the South Pole in 1911.
In some areas, instead of the polar night, the polar twilight, where the sun immerses under the horizon, but less than 10 degrees of bathing the whole landscape in an unbelievable and prolonged and prolonged. This light is enough for people to walk on the streets and work, and some cities in the north live with this twilight of the moon.
Some other planets like Pluto have so huge axIal tilt that a large percentage of their surface is experiencing polar and day. In the case of Pluto, this can lead to a temperature of up to 33 degrees Celsius above absolute zero.