CopernicanSystem


General Description

This simulation illustrates Copernicus' system of planetary motions. The entire system is centered on the center of Earth's uniform, circular orbit. Sun is placed near, but not at, this center point. The orbit of each planet (other than Earth) consists of a deferent circle, centered on a point some distance from the center (at the eccentric point). Attached to this deferent is the center of a much smaller circle, the epicycle (or epicyclet). The radius of the epicycle is 1/3 the eccentricity of the deferent. The planet moves along the epicycle at a constant angular speed equal to twice the angular speed along the deferent. This model produces retrograde motion and changes in brightness that are always properly correlated with the location of Sun. In this simulation the planet is assumed to move in the plane of the ecliptic, so its latitude is always zero.

The parameters are initially set to model the orbit of Mars. The user can select orbits for Mercury, Venus, Mars, Jupiter, Saturn, or a user-defined orbit. Parameters for the Mercury, Venus, Mars, Jupiter, and Saturn orbits are taken from Copernicus' De Revolutionibus Orbium Coelestium. The simulation can also display simplified orbits that do not use the eccentric and epicycle.

The top window shows the elements of the model. The bottom window shows the view from Earth.


Orbit Frame


Sky View Window


Orbit Parameters (for User Defined orbit)


Todd K. Timberlake (ttimberlake@berry.edu)