equator

The equator is the part of the world which, at sea level, is farthest from the axis of the Earth's spin. Since the speed of a point travelling in a circle is proportional to the distance from the centre of the circle, this means there's more centrifugal force (or centrifugal effect) than elsewhere on the planet. Launch points for rockets to space are usually near the equator to take advantage of this effect.

The equator is to the spin of the Earth's day as the ecliptic is to the orbit of the Earth's year.

E*qua"tor (?), n. [L. aequator one who equalizes: cf. F. 'equateur equator. See Equate.]

1. Geog.

The imaginary great circle on the earth's surface, everywhere equally distant from the two poles, and dividing the earth's surface into two hemispheres.

2. Astron.

The great circle of the celestial sphere, coincident with the plane of the earth's equator; -- so called because when the sun is in it, the days and nights are of equal length; hence called also the equinoctial, and on maps, globes, etc., the equinoctial line.

Equator of the sun ∨ of a planet Astron., the great circle whose plane passes through through the center of the body, and is perpendicular to its axis of revolution. -- Magnetic equator. See Aclinic.

© Webster 1913.