Comparison between three famous planetary models. Ptolemy/Copernicus/Tycho EJS Model illustrates the relationships between the systems of planetary astronomy developed by Claudius Ptolemy, Nicholas Copernicus, and Tycho Brahe. The model presents a simplified version of all three systems, showing the motions of the Sun/Earth and two planets (one inferior, one superior). The model is initially set to model the planets Venus and Mars. In addition, the apparent motion of the sun and two planets across the sky is displayed in another window.

Visual Elements:
1. Orange point/circle/lines: the Sun, its orbit (Ptolemaic and Tychonic), and the Earth-Sun line.
2. Blue point/circle: the Earth and its orbit (Copernican).
3. Yellow point/circle/lines: the inferior planet,its orbit (Copernican and Tychonic) or epicycle (Ptolemaic), and the lines connecting it to Sun and Earth.
4. Red point/circle/lines: the superior planet, its orbit (Copernican and Tychonic) or deferent (Ptolemaic), and the lines connecting it to Sun and Earth.
5. Magenta circle: Ptolemaic epicycle for the superior planet. This is really a mirror image of the Earth/Sun orbit.

Requirements:
* Java

The license of this software is Free, you can free download and free use this calculator software.