The term Sidereal astrology refers to the practise by some western and all Indian astrologers of basing their study of the sky on the actual position of the planets in relation to the starry back ground. Most modern western astrologers adopt the tropical zodiac approach and base their study on a notional view of the heavens which does not match the actual present positions of the stars.

The two approaches coincided approximately 2000 years ago but due to the precession of the equinoxes are now almost a whole zodiacal sign out of step.

See also: sidereal time