Tropic of Capricorn

Tropic of Capricorn, the parallel of latitude, or imaginary line around the earth, that marks the southern limit of the tropics or Torrid Zone, a region of consistently warm climate. The Tropic of Capricorn lies 23°27’ south of the equator and is the southern solstice—that is, it is the southernmost point where the Sun appears directly overhead at least one day a year. The Sun reaches this apparent position at noon on or about December 21 of each year; at this time it appears at its highest point in the sky as seen from the Southern Hemisphere, and its lowest point as seen from the Northern Hemisphere. This date marks the start of summer for the Southern Hemisphere and is therefore called the “summer solstice.” In the Northern Hemisphere, however, the seasons are reversed; this date marks the start of winter in the Northern Hemisphere, so people there call it the winter solstice. For the next six months the Sun at noon appears lower each day in the Southern Hemisphere and higher in the Northern Hemisphere.

The name Capricorn comes from Latin words meaning “goat horn,” and is the name of one of the 12 sectors that ancient astronomers marked off in the zodiac, the band of sky from 8° north to 8° south of the equator. In the 2nd century bc Greek astronomer Hipparchus observed that the Sun appeared to be within the boundaries of the Capricorn sector at the time of the winter solstice.

The Tropic of Capricorn divides the tropics from the Southern Temperate Zone. It crosses south central South America, southern Africa, the island of Madagascar, the Indian Ocean, central Australia, and the Pacific Ocean just south of Tonga.