Equator 赤道
An equator is the intersection of the surface of a rotating sphere with the plane that is perpendicular to the sphere's axis of rotation and midway between its poles. The equator usually refers to the Earth's equator: an imaginary line on the Earth's surface equidistant from the North Pole and South Pole, dividing the Earth into the Northern Hemisphere and Southern Hemisphere. The Equator is about 40,075 kilometres (24,901 mi) long; some 78.7% lies across water and 21.3% over land. Other planets and astronomical bodies have equators similarly defined.