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Last updated on April 19, 2014 at 8:45 EDT

Tropic of Capricorn

The Tropic of Capricorn, alternately called the Southern Tropic, is a marker of the most southerly latitude on the Earth at which the Sun can be directly overhead. This occurs at the December solstice, when the southern hemisphere is tilted towards the sun at its maximum degree.

It is one of the five major circles of latitude that mark maps of the Earth. It presently lies 23 degrees 26’ 16’’ south of the Equator.

Currently, the Tropic of Capricorn is drifting towards the north at the rate of almost half a second of latitude, which is roughly 15 meters per year.

The Tropic of Capricorn is the separating line between the Southern Temperate Zone towards the south and the tropics towards the north. The position isn’t fixed, but rather it varies in a complicated manner over time.

Much like the Tropic of Cancer, most places that lie along the Tropic of Capricorn have arid or semi-arid climates, though with the Tropic of Capricorn this unfavorable environmental state is aggravated by the fact that in Australia and Southern Africa, glaciation and tectonic activity have been largely absent since the Carboniferous period 300 million years ago, so that the aridity is compounded by tremendously infertile soils.

This Tropic of Capricorn is so named due to when the Sun reaches the zenith at this latitude, it’s entering the tropical sign of Capricorn. When it was named, roughly 2 thousand years ago, the sun was also in the direction of the constellation Capricornus at the December solstice.

Image Caption: World map with tropic of capricorn in SVG format. Credit: Thesevenseas/Wikipedia (CC BY-SA 3.0)

Tropic of Capricorn