Tropic of Cancer

2008/9 Schools Wikipedia Selection. Related subjects: Geography

World map showing the Tropic of Cancer

The Tropic of Cancer, or Northern tropic, is one of five major circles of latitude that mark maps of the Earth. It is the northernmost latitude at which the Sun can appear directly overhead at noon. This event occurs at the June solstice, when the northern hemisphere is tilted towards the sun to its maximum extent.

The Tropic of Cancer currently lies 23° 26′ 22″ north of the Equator. North of this latitude are the subtropics and Northern Temperate Zone. The equivalent line of latitude south of the Equator is called the Tropic of Capricorn, and the region between the two, centered on the Equator, is known as the Tropics.

The line is called Tropic of Cancer because when it was named the sun was in the location of the constellation of Cancer (Latin for crab) in the sky at the June solstice. However, due to the precession of the equinoxes, the sun is now in the location of the constellation of Taurus at the June solstice. The word "tropic" itself comes from the Greek tropos, meaning turn, referring to the fact that the sun appears to "turn back" at the solstices.

The position of the Tropic of Cancer is not fixed, but varies in a complex manner over time; see under circles of latitude for information.

Geography

Vandalized monument marking the Tropic of Cancer northeast of Villa de Cos, Zacatecas, Mexico.

Starting at the Prime Meridian and heading eastwards, the Tropic of Cancer passes through:

Country, territory or sea	Notes
Algeria
Niger
Libya	The Tropic touches on the northernmost point of  Chad
Egypt
Red Sea
Saudi Arabia
United Arab Emirates	Abu Dhabi emirate only
Oman
Indian Ocean	Arabian Sea
India
Bangladesh
India
Bangladesh
India
Myanmar (Burma)
China
Taiwan Strait
Republic of China	Taiwan, claimed by  China
Pacific Ocean
United States	Hawaii — sea area only, misses every island, passing between Nihoa and Necker Island
Mexico	Baja California peninsula
Gulf of California
Mexico
Gulf of Mexico
Straits of Florida
Bahamas	Exuma Islands and Long Island
Atlantic Ocean
Western Sahara	Claimed by  Morocco
Mauritania
Mali
Algeria

Circumnavigation

According to the Fédération Aéronautique Internationale's rules, for a flight to compete for a round-the-world speed record, it must cover a distance no less than the length of the Tropic of Cancer as well as cross all meridians and end on the same airfield where it started. This length is set to be 36787.559 kilometres - a number implying a precision which does not exist, considering the variations of the tropic described above.

For an ordinary circumnavigation the rules are somewhat relaxed and the distance is set to a rounded value of 37000 kilometres.