e
pi
cy
cle
Plural
epicycles
1
(astronomy) a secondary circular orbit embedded within a primary circular orbit
- In his astronomical work the Almagest, Ptolemy used a system of deferents and epicycles to explain the observed motions of planets across the night sky.
- Copernicus disagreed with the Ptolemaic model adding unnecessary epicycles, believing instead that planets revolve in simpler circular orbits around the Sun.
2
a small circle whose center moves around the circumference of a larger circle
- The concept of an epicycle allows for the modeling of complex periodic movements in geometry and astronomy.
- The motion of a point on an epicycle can be described mathematically by combining the rotations of the smaller circle and the larger circle.
- The geometric properties of an epicycle can be explored by examining the resulting curves and paths generated by its motion.
- An epicycle can be visualized by imagining a small wheel rolling around the edge of a larger wheel.
- When the center of the epicycle moves along the circumference of the deferent, the resulting path of a point on the epicycle is known as an epicycloid.