The tropics are the region of Earth surrounding the Equator. They are delimited in latitude by the Tropic of Cancer in the Northern Hemisphere at 23°26′11.5″ (or 23.43652°) N and the Tropic of Capricorn in the Southern Hemisphere at 23°26′11.5″ (or 23.43652°) S; these latitudes correspond to the axial tilt of the Earth. The tropics are also referred to as the tropical zone and the torrid zone. The tropics include all zones on Earth where the Sun contacts a point directly overhead at least once during the solar year. Thus the maximum latitudes of the tropics have the same value positive and negative. Likewise, they approximate, due to the earth not being a perfect sphere, the "angle" of the Earth's axial tilt. The "angle" itself is not perfectly fixed due chiefly to the influence of the moon, but the limits of tropics are a geographic convention, being an averaged form, and the variance is very small.
