Astronomy for Astrologers
direction - the Vernal Equinox - to the object's hour
circle). In Figure C, the darker lines express the position
of a star (S) in both ecliptic and equatorial coordinates.
Equatorial Sphere - Also called the Celestial Sphere,
this is the sphere resulting from projecting the Earth
infinitely into space; it is defined by the celestial equator,
and the north and south celestial poles.
Celestial Poles - These are directly overhead the Earth's
geographic poles and are the poles of rotation of the
celestial sphere of right ascension and declination.
NCP - North Celestial Pole
SCP - South Celestial Pole
Celestial Equator - A great circle projected from the
Earth's equator into the heavens—an infinite projection.
The celestial equator has, as its poles, the celestial
poles, and all points on the celestial equator are
equidistant from these two poles. As the Earth's equator
rotates each day, it exposes each city on the equator to
every degree of the celestial equator.
Equinoctial - Another term for the celestial equator.
Celestial Sphere - An infinite extension of the sphere of
the Earth in space.
Hour Circles - Hour circles are great circles passing
through any celestial object and through the celestial
poles. All hour circles are at right angles to the celestial
equator.
R.A. - (See Right Ascension)
Right Ascension (R.A.) - The angle between an hour
circle passing through an object and the meridian
plane—in the case of equatorial coordinates, zero
degrees of Aries. R.A. is measured eastward on the
celestial equator from what is called the True Equinox,