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.

Epicycle.png

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