celestial equator

noun

Astronomy, Navigation.

1. the great circle of the celestial sphere, lying in the same plane as the earth's equator.

celestial equator

noun

1. Also called: equinoctial.  equinoctial circle. the great circle lying on the celestial sphere the plane of which is perpendicular to the line joining the north and south celestial poles

celestial equator

1. A great circle separating the northern and southern hemispheres of the celestial sphere and lying in the same plane as the Earth's equator. The celestial equator is a projection of the Earth's equator outward onto the celestial sphere and is used as the reference point in determining a celestial body's declination.

Word History and Origins

Origin of celestial equator¹

First recorded in 1870–75