On the map shown, and for that matter on all other maps, the Arctic Circle, Antarctic Circle, Equator, Prime Meridian, Tropic of Cancer and Tropic of Capricorn are imaginary lines.
It is one of the five major circles of latitude that mark maps of the Earth. Its exact location varies slightly each year, and currently it's positioned at 66° 33′ 44″ (or 66.5622°) north of the Equator.
Antarctic Circle: This parallel of latitude is currently at 66° 33′ 44″ ( or 66.5622°) south of the Equator.
NOTE: The position of the Arctic and Antarctic Circles are not fixed, as their exact location depends on the Earth's axial tilt, which fluctuates within a margin of 2° over a 40,000 year period, mainly due to tidal forces resulting from the orbit of the Moon.
Located at zero degrees latitude (North or South,) it is 24,901.55 miles long and divides the Planet Earth into the Northern and Southern Hemispheres.
Tropics of Cancer and Capricorn
Located at 23.5 degrees North and 23.5 degrees South of the Equator, this area of Planet Earth (between those two lines) is known as the "Tropics," and is colored with a lighter blue color on the globe. This area experiences no dramatic change in season because the sun is consistently high in the sky throughout the year.
People living North of the Tropic of Cancer and South of the Tropic of Capricorn experience dramatic seasonal climate changes, based on the earth's tilt, and the subsequent angle of the sun. When it's summer North of the Tropic of Cancer, it's winter South of the Tropic of Capricorn. (The reverse is also true).
Located at zero degrees longitude (East or West), it divides the Planet Earth into the Eastern and Western Hemispheres, and is the line from which all other lines of longitude are measured.