"Adding epicycles" has come to be used as a derogatory comment in modern scientific discussion. The term might be used, for example, to describe continuing to try to adjust a theory to make its …

In the Ptolemaic system each planet revolves uniformly along a circular path (epicycle), the centre of which revolves around Earth along a larger circular path (deferent). Because one half of an epicycle …

The meaning of EPICYCLE is a circle in which a planet moves and which has a center that is itself carried around at the same time on the circumference of a larger circle.

What it shows: Long before the time of Copernicus, the Greek astronomer Claudius Ptolemy created a model of all the planets' observed celestial motions. The model involved combinations of perfect …

Ptolemy used epicycles to try to explain the apparent change in motion of the planets within their orbits. Planets appear to slow down, go in reverse, and then continue along their orbital paths...

Epicycles were used to explain the retrograde motion of the planets, where they appear to temporarily move backwards in the sky. The Ptolemaic system, which dominated Western astronomy for over a …

The small circle centered around Point A at the top of the figure is an example of an epicycle. The idea was, the center of the epicycle (Point A) would rotate uniformly around the Earth (Object E), while the …

Mar 18, 2025 · What is an epicycle? An epicycle is a small circle whose center moves around the circumference of a larger one. This concept, rooted in ancient astronomy, was used to explain the …

May 5, 2001 · As a planet moves around on its epicycle, the center of the epicycle (called the ``deferent'') moves around the Earth. When its motion brings it inside the deferent circle, the planet …

Learn how epicycles work and the different relationships the superior and inferior planets share.