Astronomy for Astrologers
Equatorial Coordinates
Equatorial Coordinates - In this system, the Earth's
Equator is the plane of reference. The poles are at the
intersection of the Earth's pole and the pole of the
celestial sphere, an imaginary surface, at an infinite
distance, with the Earth as its center. This is true for all
points on the Earth—latitude and longitude both. The
poles are the North Celestial Pole (NCP) and South
Celestial Pole (SCP). The circle at the intersection of the
plane of the Earth's equator and the celestial sphere is
the Celestial Equator.
The great circle through the celestial poles and an
object (such as a star) is the object's Hour Circle and
the great circle which passes through the celestial poles
and the zenith is the Meridian Circle. The coordinates in
this system are given by Declination (angle between the
celestial equator and the object) and the Right
Ascension (angle measured from an arbitrary reference