Tropic of Cancer is an imaginary line that traces the northern boundary of the earth’s Tropical Zone. It marks the farthest limit north of the equator where the sun can appear directly overhead. The line lies 23 degrees 27 minutes north of the equator. The vertical rays of the sun shine down on the Tropic of Cancer at noon on the day of the summer solstice, which is June 20, 21, or 22.
The Tropic of Cancer passes through many lands with a variety of climates. It crosses Mexico, passes between Florida and Cuba, and crosses the Sahara, Arabia, north-central India, and southern China. It crosses the Pacific Ocean immediately north of the main islands of Hawaii. The word Cancer means crab in Latin, and refers to a constellation of the zodiac. The position of the Tropic of Cancer on the map was first marked by its location directly beneath the constellation of Cancer. The inclination of the earth to the plane of its orbit determines the constellation’s position. To an observer on the Tropic of Cancer, the North Star appears at an angle of 23 degrees 27 minutes above the horizon.
