equator Name given to two imaginary circles. The terrestrial Equator lies midway between the North Pole and South Pole and is the zero line from which latitude is measured. It divides the Earth into the Southern and Northern Hemispheres. The celestial equator lies directly above the Earth's Equator, and is used as a reference to determine the position of a star using the astronomical co-ordinate system of right ascension and declination.

e·qua·tor / iˈkwātər/ • n. an imaginary line drawn around the earth equally distant from both poles, dividing the earth into northern and southern hemispheres and constituting the parallel of latitude 0°. ∎  a corresponding line on a planet or other body.

equator great circle of the celestial sphere XIV; great circle of the earth XVII. — (O)F. équateur or medL. æquātor, in full circulus æquator diei et noctis circle equalizing day and night. f. æquāre (see prec.).

143. Equator

See also 133. EARTH ; 178. GEOGRAPHY

antipodes

two points on the surface of the earth diametrically opposite each other. —antipodean , n. , adj.

Antiscians, Antiscii

persons living on opposite sides of the equator but in the same longitude whose shadows at noon fall in opposite directions.

equator a line notionally drawn on the earth equidistant from the poles, dividing the earth into northern and southern hemispheres and constituting the parallel of latitude 0°. The term is recorded from late Middle English, and comes from medieval Latin aequator, in the phrase circulus aequator diei et noctis ‘circle equalizing day and night’.