By Ronni Dee | Updated Mar 24, 2022
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The five major circles of latitude—commonly called the Equator, the Tropics of Cancer and Capricorn, and the Arctic and Antarctic Circles—define key climatic and geographic zones on Earth. Each circle is a specific latitude that intersects every line of longitude, pinpointing distinct regions on the globe.
The major latitude lines are the Equator, the Tropics of Cancer and Capricorn, and the Arctic and Antarctic Circles.
Situated at approximately 66.5° N, the Arctic Circle marks the boundary beyond which the sun does not rise during the winter solstice and does not set during the summer solstice. It traverses eight countries—Canada, Greenland, Iceland, Norway, Sweden, Finland, Russia, and the United States—highlighting the extreme northern environment.
Located at roughly 66.5° S, the Antarctic Circle delineates the southernmost latitude where the sun experiences the same prolonged daylight and darkness extremes. This circle encircles the continent of Antarctica, the only landmass within its bounds and home to no permanent human residents.
The Equator, at 0° latitude, is the most familiar circle of latitude. It divides the planet into the Northern and Southern Hemispheres and spans about 25,000 miles in circumference. All other latitude measurements are expressed relative to this central line.
At approximately 23.5° N lies the Tropic of Cancer, the northern limit of the tropics. During the northern hemisphere’s summer solstice, the sun is directly overhead at noon along this line—marking the farthest point north where the sun can appear zenith.
Conversely, the Tropic of Capricorn sits at about 23.5° S, defining the southern boundary of the tropics. In the Southern Hemisphere’s summer solstice, the sun reaches its zenith over this latitude, making it the farthest south point of direct overhead sunlight.
