written by Todd Timberlake

The 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.

This model can be used to illustrate the essential geometric equivalence between these three system.  In particular, it shows that the Earth's orbit (in the Copernican system) becomes the orbit of the sun in the Ptolemaic and Tychonic systems, and also appears as the deferent of Venus and epicycle of Mars in the Ptolemaic system.  The orbit of Venus about the sun (in the Copernican and Tychonic systems) becomes
the epicycle of Venus in the Ptolemaic system.  The orbit of Mars about the sun (in the Copernican and Tychonic systems) becomes the deferent of Mars in the Ptolemaic system.

• Download ejs_astronomy_PtolemyCopernicusTycho.jar - 1699kb Java Archive File

Last Modified June 11, 2014

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This zip archive contains LaTeX and PDF versions of a handout for an activity that allows students to explore the Ptolemy Copernicus Tycho Model.  The activity focuses on the general geometrical equivalence of the three models, as well as the specific connections between the different models.

• Download TychonicActivities.zip - 86kb Compressed File

Published January 4, 2013
Last Modified January 4, 2013

The source code zip archive contains an XML representation of the EJS Ptolemy/Copernicus/Tycho Model.   Unzip this archive in your EJS workspace to compile and run this model using EJS.

• Download ejs_PtolemyCopernicusTycho.zip - 155kb Compressed File

Released under a This material is released under the GNU General Public License Version 3.

Published May 12, 2011
Last Modified June 11, 2014

This file has previous versions.