Equator

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Equator, great circle around the Earth that is everywhere equidistant from the geographic poles and lies in a plane perpendicular to the Earth’s axis. This geographic, or terrestrial, Equator divides the Earth into the Northern and Southern hemispheres and forms the imaginary reference line on the Earth’s surface from which latitude is reckoned; in other words, it is the line with 0° latitude.

In astronomy, thecelestial equator is the great circle in which the plane of the terrestrial Equator intersects the
celestial sphere ; it consequently is equidistant from the celestial poles. When the Sun lies in its plane, day ... (100 of 126 words)