Ecliptic

Ecliptic, in Astronomy, is the path in the celestial sphere apparently taken by the sun during each year. It is a great circle, cutting the celestial equator at two points 180° apart, and making with it an angle of about 23J. It defines the plane in which the earth is moving round the sun. The name was given to it by early astronomers, who observed that eclipses only occurred when the moon was crossing it. [Eclipses.]