vertical circleA great circle of the celestial sphere, through the zenith and nadir. Vertical circles are perpendicular to the horizon. The prime vertical circle or prime vertical passes through the east and west points of the horizon. The principal vertical circle passes through the north and south points of the horizon and coincides with the celestial meridian. Related category• CELESTIAL MECHANICSAlso on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History |