The Tropic of Cancer, also referred to as the Northern tropic, is the circle of latitude on the Earth that marks the most northerly position at which the Sun may appear directly overhead at its zenith. This event occurs once per year, at the time of the June solstice, when theNorthern Hemisphere is tilted toward the Sun to its maximum extent. It currently (Year 2013) lies at 23° 26′ 15.143″ north of the Equator.
Its Southern Hemisphere counterpart, marking the most southerly position at which the Sun may appear directly overhead, is the Tropic of Capricorn. These tropics are two of the five major degree measuresor major circles of latitude that mark maps of the Earth, besides theArctic and Antarctic Circles and the Equator. The positions of these circles of latitude (other than the Equator) are dictated by the tilt of the Earth's axis of rotation relative to the plane of its orbit.