Astrology is the study of celestial bodies interpreted as affecting personality, human affairs, and natural events. The primary astrological bodies are the Sun, Moon, and planets, which are analyzed by their aspects (relative positions to one another), by their placement in 'houses' (spatial divisions of the sky), and their movement through signs of the zodiac (spatial divisions of the ecliptic).
Ancient civilizations developed it as a calendrical system to predict seasonal shifts and to interpret celestial cycles as ‘signs’ of ‘divine communications’.
Historically it was a learned tradition, sustained in courts, cultural centers and universities, and was closely related to the studies of astronomy, alchemy, meteorology, and medicine. Yet despite their closely connected histories, astrology and astronomy separated at the end of the 17th century, when astronomy redefined many of the theoretical concepts that the two disciplines had previously shared.
Subsequently, astrology suffered a decline in academic and theoretical credibility. The 20th century brought renewed attention, partly through the popularizing effect of newspaper horoscopes and New Age philosophies, and through re-kindled intellectual interest in statistically testing astrology's claims. Astrologers have long debated the degree of determinism in astrology. Some believe that celestial movements control fate, others that they determine only disposition and potential.
While most astrologers contend there is no direct influence from the stars (only a synchronistic correlation between the celestial and terrestrial) astrology has been criticized for not offering a clear account of its physical mechanism and failing to develop new theories in line with modern scientific principles. It has thus been called a pseudoscientific subject by members of the modern scientific community.