1. The study of the positions and the movements of the stars, planets, and other heavenly bodies in the belief that these affect people's lives.
2. A nonscientific system that attempts to explain or predict human actions and events by the position of celestial objects.
3. The study of the relative positions of the sun, moon, and planets in order to estimate their supposed influences on human events.
4. A pseudoscience that claims to be able to predict one's destiny according to the position of celestial bodies when one was born and which has been widely discredited by science.

Despite modern science's lack of regard for astrology, the work of the early astrologers was of great value in the development of astronomy, principally because of their accurate obsersvations and records of star positions.

The problem is that the conclusions that those astrologers drew from their observations depended far more on supernatural beliefs than on scientific principles; for example, from calculations known only to themselves, they plotted charts called horoscopes, from which they attempted to predict and influence future events.

Purposes of astrology

Astrologers cast a horoscope by first determining for the given moment and locality the boundaries of the twelve places and the longitudes and latitudes of the seven planets.

They read this horoscope by examining the intricate geometric interrelationships of the signs and their parts and of the planets of varying computed strengths with the places and each other and by associating with each element in the horoscope its list of sublunary correspondences.

Any horoscopic diagram, of course, will yield a vast number of predictions, including many that are contradictory or extravagant.

So astrologers must rely on their knowledge of the client’s social, ethnic, and economic background and on their own experiences to guide them in avoiding errors and attaining credibility.

Despite criticisms, astrology continues to attract people from all walks of life; from the casual followers who read their horoscopes in the daily newspaper to those who have their star charts drafted by professional astrologers.

In short, even though it is regarded by many as devoid of intellectual value, astrology in its modern and historical forms remains of great interest to scholars and a wide spectrum of the general public.

The supposed "science" of the stars, anciently equivalent to astronomy, which was known as natural astrology, and used to predict such natural events as eclipses, the date of Easter, and meteorological phenomena unit.