Definition:Epicycle (Ptolemaic Astronomy)
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This page is about Epicycle in the context of Ptolemaic Astronomy. For other uses, see Epicycle.
Definition
An epicycle is the orbit described by a body moving in a uniform circular motion around a point which is itself moving in a uniform circular motion around another point.
That point may itself also be moving in a uniform circular motion around yet another point.
Also see
Historical Note
Claudius Ptolemy's Almagest modelled the orbits of the planets of the solar system as a system of epicycles.
They modelled the actual behaviour of the planets to a high degree of accuracy.
However, when the heliocentric model of the solar system was proposed, it was realised that the latter model was considerably simpler.
Sources
- 1989: Ephraim J. Borowski and Jonathan M. Borwein: Dictionary of Mathematics ... (previous) ... (next): epicycle: 2. (Ptolemaic astronomy)
- 1992: George F. Simmons: Calculus Gems ... (previous) ... (next): Chapter $\text {B}.25$: Kepler's Laws and Newton's Law of Gravitation
- 2008: Ian Stewart: Taming the Infinite ... (previous) ... (next): Chapter $5$: Eternal Triangles: Base ten logarithms