Epicycle

Definition

An epicycle is a small circular path whose center travels around a larger circle, traditionally called the deferent. Ancient and medieval astronomers used combinations of these circles to model planetary motion in a geocentric cosmos. The system helped account for observed changes in speed, direction, and distance, especially the apparent backward movement known as retrograde motion.

Astrological Meaning

In classical astrology, an epicycle is primarily an astronomical and computational concept rather than a standalone symbol with a natal interpretation. Epicyclic models allowed astrologers to estimate planetary positions, which were then used to cast horoscopes and assess signs, houses, aspects, dignities, and planetary phases. Understanding the term can clarify how traditional practitioners worked before heliocentric models and modern orbital calculations became standard.

Why It Matters

Epicycles matter because accurate planetary placement has always been fundamental to chart interpretation. The concept also shows how astrology developed alongside historical astronomy and adapted to changing models of the heavens. A modern astrologer does not usually interpret an epicycle directly, but recognizing its role provides useful context for traditional texts, old planetary tables, and the history of retrograde motion.

Related Encyclopedia Entries

• Traditional Astrology
• Astrological Terminology
• Natal Chart