A world map. The Antarctic Circle is shown as the red line.

The Antarctic Circle is one of the five major circles of latitude that mark maps of the Earth. It is the parallel of latitude at 66° 33′ 39″ south of the Equator, crossing mostly the Southern Ocean.

In the Antarctic Circle, all places have twenty-four hours of daylight on the Summer Solstice in December. In June on the Winter Solstice all places have twenty-four hours of night. There is a minimum of one whole day that the sun does not set and one whole day that the sun does not rise.