+The Polar Circle defines the boundaries of Earth's [polar regions](/wiki/polar_regions), marking where the sun remains visible for 24 hours (midnight sun) or not at all (polar night) at least once a year. These significant lines of [latitude](/wiki/latitude) are the [Arctic Circle](/wiki/arctic_circle) in the north and the [Antarctic Circle](/wiki/antarctic_circle) in the south. Their exact positions shift slightly with Earth's axial tilt.
+## See also
+- [Arctic](/wiki/arctic)
+- [Antarctica](/wiki/antarctica)
+- [Tropic](/wiki/tropic)
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