An Etymological Dictionary of Astronomy and Astrophysics

A parallel of latitude on the Earth, 23°26’ north of the equator, where the Sun is directly overhead on the northern → summer solstice (around the 21st June each year), because the Sun reaches its most northerly declination. Some 3,000 years ago, this occurred when the Sun was in the → Zodiac constellation → Cancer, hence the name. However, → precession has resulted in a shift of the position of the Sun so that it is now in the constellation → Gemini on the summer solstice.

See also: → tropic; → Cancer.