Tropic of Cancer is also the name of a novel by Henry Miller, first published in 1934.

The Tropic of Cancer (cancer (♋) is Latin for crab) is one of the five major circles of latitude that mark maps of the Earth. This is the parallel of latitude that runs 23° 26' 22" north of the Equator, and is the farthest northern latitude at which the sun can appear directly overhead. North of this line is the Northern Temperate Zone. South of this line are the Tropics. This line is called the Tropic of Cancer because, when the sun appears directly overhead, at this latitude, during the summer solstice in June, it used to be in the Zodiac sign of Cancer. However, due to precession of the equinoxes, the June solstice is now in the constellation Taurus. The Tropic of Capricorn is at the opposite latitude south of the Equator.

According to FAI's rules, to qualify as a circumnavigation a flight must be not less than the length of of Tropic of Cancer (36,787.559 km), as well as cross all meridians and end on the same airfield where it started.