What is the significance of the Arctic and Antarctic circles?
The Arctic Circle marks the southern extremity of the polar day (24 hour sunlit day, often referred to as the “midnight sun”) and polar night (24 hour sunless night). North of the Arctic Circle, the sun is above the horizon for 24 continuous hours at least once per year, and below the horizon for 24 continuous hours at least once per year. On the Arctic Circle these events occur, in principle, exactly once per year, at the June and December solstices respectively. It is called the Arctic because it corresponds to the southernmost point of the Constellation Ursa Major (the Great Bear or Megale Arktos in Greek). The Antarctic Circle is one of the five major circles (or parallels) of latitude that mark maps of the Earth. As of 2000, it lies at latitude 66° 33′ 39″ south of the equator. The area south of the Antarctic Circle is known as the Antarctic, and the zone immediately to the north is called the Southern Temperate Zone. The equivalent line of latitude in the northern hemisphere is t
The first poster is quite correct but I think more detail is needed. Because of the inclination, the Arctic Circle marks the start of the area where, for at least one day each year, the sun does not completely set (June 21) or rise (December 22). This is also true for the Antarctic Circle. It marks the start of the area where, for at least one day each year, the sun does not completely set (December 22) or rise (June 21). There are area within the both circles that will receive continuous daylight for 6 months of the year and continuous darkness for the other 6 months. Most places however receive some daylight and some darkness. When the areas in the Arctic are experiencing their light periods the areas in the Antarctic are in their darkness and vice versa. That is why there is the phrase ‘Land of the Midnight Sun’. If you lived north of the Arctic Circle, Dec 22 would be important. It is the winter solstice day, the day that the sun starts coming back. Here is an excellent site that e
