equator definition
An equator is the intersection of a sphere 's surface with the plane perpendicular to the sphere's axis of rotation and midway between the poles.he latitude of the Earth's Equator is by definition 0Â° (zero degrees). The Equator is one of the five notable circles of latitude on Earth, with the others being the two Polar Circles: the Arctic Circle and the Antarctic Circle, and the two Tropical Circles: the Tropic of Cancer and the Tropic of Capricorn.