Referring to the time when the sun passes the celestial equator.
The celestial equator, like the terrestrial, is 90° from the pole.
The angle of elevation of the celestial equator to the horizon varies according to the position of the observer.
Then the zenith would be on the celestial equator and the north and south poles of the heavens would be on the horizon.
When the sun is south of the celestial equator its apparent daily path is the same as it would be for a star so situated.
The line of intersection will be a great circle of the celestial sphere, called the celestial equator.
The Celestial Equator is a great circle of the sky distant 90 from the poles.
We may remark that the main part of the zodiacal light shifts to the south side of the celestial equator as we cross the line.
Its plane is inclined about 63 to the celestial equator and its poles lie in the constellations of Coma Berenicis and Cetus.
The celestial equator is the great circle in which the plane of the earth's equator intersects the celestial sphere.