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Copernican System Model
written by Todd Timberlake
The Ejs Copernican System model 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. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item.

Ejs Copernican System model was created using the Easy Java Simulations  (Ejs) modeling tool.  It is distributed as a ready-to-run (compiled) Java archive.   Double clicking the ejs_astronomy_CopernicanSystem.jar file will run the program if  Java is installed.  Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models.  Additional Ejs models for astronomy are available.  They can be found by searching ComPADRE for  Open Source Physics, OSP, or Ejs.

Please note that this resource requires at least version 1.5 of Java (JRE).
1 supplemental document is available
1 source code document is available
Subjects Levels Resource Types
- Astronomy Education
= Curricula
- Solar System
= Earth
= Jupiter
= Mars
= Saturn
- Lower Undergraduate
- Middle School
- High School
- Instructional Material
= Interactive Simulation
Intended Users Formats Ratings
- Educators
- Learners
- General Publics
- application/java
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Access Rights:
Free access
This material is released under a Creative Commons Attribution 3.0 license.
Rights Holder:
Todd Timberlake
Copernican, Copernicus, EJS, Easy Java Simulations, OSP, Open Source Physics
Record Cloner:
Metadata instance created August 18, 2009 by Mario Belloni
Record Updated:
June 3, 2014 by Andreu Glasmann
Last Update
when Cataloged:
August 18, 2009
Other Collections:

ComPADRE is beta testing Citation Styles!

Record Link
AIP Format
T. Timberlake, Computer Program COPERNICAN SYSTEM MODEL, Version 1.0 (2009), WWW Document, (https://www.compadre.org/Repository/document/ServeFile.cfm?ID=9382&DocID=1284).
T. Timberlake, Computer Program COPERNICAN SYSTEM MODEL, Version 1.0 (2009), <https://www.compadre.org/Repository/document/ServeFile.cfm?ID=9382&DocID=1284>.
APA Format
Timberlake, T. (2009). Copernican System Model (Version 1.0) [Computer software]. Retrieved October 16, 2017, from https://www.compadre.org/Repository/document/ServeFile.cfm?ID=9382&DocID=1284
Chicago Format
Timberlake, Todd. "Copernican System Model." Version 1.0. https://www.compadre.org/Repository/document/ServeFile.cfm?ID=9382&DocID=1284 (accessed 16 October 2017).
MLA Format
Timberlake, Todd. Copernican System Model. Vers. 1.0. Computer software. 2009. Java (JRE) 1.5. 16 Oct. 2017 <https://www.compadre.org/Repository/document/ServeFile.cfm?ID=9382&DocID=1284>.
BibTeX Export Format
@misc{ Author = "Todd Timberlake", Title = {Copernican System Model}, Month = {August}, Year = {2009} }
Refer Export Format

%A Todd Timberlake
%T Copernican System Model
%D August 18, 2009
%U https://www.compadre.org/Repository/document/ServeFile.cfm?ID=9382&DocID=1284
%O 1.0
%O application/java

EndNote Export Format

%0 Computer Program
%A Timberlake, Todd
%D August 18, 2009
%T Copernican System Model
%7 1.0
%8 August 18, 2009
%U https://www.compadre.org/Repository/document/ServeFile.cfm?ID=9382&DocID=1284

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Citation Source Information

The AIP Style presented is based on information from the AIP Style Manual.

The APA Style presented is based on information from APA Style.org: Electronic References.

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Copernican System Model:

Is Based On Easy Java Simulations Modeling and Authoring Tool

The Easy Java Simulations Modeling and Authoring Tool is needed to explore the computational model used in the EJS Copernican System Model.

relation by Mario Belloni

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