A circle or belt, which anciently was said to extend some 8 degrees on either side of the ecliptic (q.v.). Modern astronomers have widened it to 9 degrees either side, because of the extreme latitudes to which Venus and Mars attain. The position of any planet within, or of any star within or outside of the zodiax, is measured by a perpendicular to the ecliptic. The point where this perpendicular meets the ecliptic is the geocentric longitude of the star or planet. In a sense, the zodiac is identical with the ecliptic, for both are measured from a point of beginning at the Vernal Equinox. v. Celestial Sphere.
ASTROLABE ENCYCLOPEDIA
