The Tropic of Cancer is the line of latitude at about 23.5 degrees north.
It marks the northernmost latitude at which the Sun can appear directly overhead at noon. This occurs around the June solstice, when Earth’s northern hemisphere is tilted toward the Sun. The line is one of the two tropical circles; the Tropic of Capricorn lies at a corresponding latitude south of the Equator.
The Tropic of Cancer is not fixed at exactly 23.5 degrees because Earth’s axial tilt changes slowly over time. It currently lies near 23 degrees 26 minutes north and gradually shifts because of variations in Earth’s obliquity. Its name comes from the zodiac constellation Cancer, although the Sun’s June-solstice position is now associated with Gemini because of the precession of Earth’s axis.