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How did the geocentric model of the universe shape ancient astrological theories?
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astrology
Zodiac wheel showing the 12 astrological constellations or signs from an illumination of the poem Breviari d'Amour, Catalan (Spain), late 14th century; in the collection of the British Library.
The geocentric model, which posits that a stationary Earth sits at the center of the universe, was foundational to the development of ancient astrology. By establishing Earth as the central reference point, this cosmology provided the framework for the "macrocosm-microcosm" correspondence—the belief that the movements of celestial bodies directly reflect or influence terrestrial life.123
This model shaped astrological theory in several key ways:
- The Zodiac and Houses: Astrologers viewed the ecliptic as a circle divided into 12 signs. Because the zodiac appeared to rotate daily around the Earth, observers defined the "ascendant" sign at the eastern horizon as the first of 12 "places" or houses, which were used to determine specific aspects of an individual's life.1
- Planetary Motion: To account for observed irregularities like retrograde motion from a geocentric perspective, ancient theorists utilized complex systems of epicycles and eccentric orbits. These motions were interpreted as indicators of a planet's strength or influence.31
- Physical Correspondence: Influenced by Aristotelian physics, astrologers integrated the geocentric view with the four elements (fire, air, water, earth). They believed celestial bodies exerted physical effects on the sublunar world, creating a system where planetary positions and configurations dictated trends in human character and events.42