Liberal Dictionary English Dictionary
noun
- the great circle on a sphere or heavenly body whose plane is perpendicular to the axis, equidistant everywhere from the two poles of the sphere or heavenly body.
- the great circle of the earth that is equidistant from the North Pole and South Pole.
- a circle separating a surface into two congruent parts.
- celestial equator.
noun
- the great circle of the earth with a latitude of 0°, lying equidistant from the poles; dividing the N and S hemispheres
- a circle dividing a sphere or other surface into two equal symmetrical parts
- See magnetic equator
- astronomy See celestial equator
late 14c., from Medieval Latin aequator diei et noctis “equalizer of day and night” (when the sun is on the celestial equator, twice annually, day and night are of equal length), agent noun from Latin aequare “make equal” (see equate). Sense of “celestial equator” is earliest, extension to “terrestrial line midway between the poles” first recorded in English 1610s.
- An imaginary line forming a great circle around the Earth’s surface, equidistant from the poles and in a plane perpendicular to the Earth’s axis of rotation. It divides the Earth into the Northern and Southern hemispheres and is the basis from which latitude is measured.
- A similar circle on the surface of any celestial body.
- The celestial equator.
An imaginary circle around the Earth, equidistant from the North Pole and South Pole.