Computer Program Detail Page
This record is currently in the approval process for inclusion into the Nucleus collection. If you feel this record should be given priority you may contact the editor using our feedback form.
Spheres of Eudoxus
written by Todd Timberlake
This Spheres of Eudoxus model simulates the system devised by the Ancient Greek astronomer Eudoxus to model the motion of the planets. The model consists of four nested concentric spheres. The axis of each sphere is attached to the surface of the next sphere out. The planet itself is located on the surface of the innermost sphere. The outermost sphere rotates with the daily (apparent) rotation of the stars.
The Spheres Frame shows the four spheres of the model. The axis of the inner (red) sphere can be tilted relative to that of the middle (blue) sphere using a slider to adjust the angle. The red sphere automatically rotates with angular velocity +1.0 (in arbitrary units). The angular velocities of the blue and green spheres can be adjusted using sliders. Note that the axis of the blue sphere is attached to the equator of the green sphere. This is a crucial part of Eudoxus' model. The equator of the green sphere is in the plane of the ecliptic. The outermost (white) sphere is essentially the Celestial Sphere containing the fixed stars (or at least it rotates about the same axis and at the same rate as the Celestial Sphere).
The Sky View Frame shows the motion of the planet (relative to the stars) as seen from the earth, which sits at the center of the concentric spheres in the model.
By tilting the red sphere relative to the blue sphere, setting the angular velocity of the blue sphere opposite that of the red sphere, and giving the green sphere a sufficiently small angular speed, Eudoxus was able to qualitatively reproduce the observed retrograde motion of the planets using this model.
Please note that this resource requires at least version 1.5 of Java (JRE).
1 source code document is available
The source code zip archive contains an XML representation of the EJS Spheres of Eudoxus Model. Unzip this archive in your EJS workspace to compile and run this model using EJS.
download 61kb .zip
Published: May 12, 2011
Rights: This material is released under the GNU General Public License Version 3.
ComPADRE is beta testing Citation Styles!
Disclaimer: ComPADRE offers citation styles as a guide only. We cannot offer interpretations about citations as this is an automated procedure. Please refer to the style manuals in the Citation Source Information area for clarifications.
Citation Source Information
The APA Style presented is based on information from APA Style.org: Electronic References.
The Chicago Style presented is based on information from Examples of Chicago-Style Documentation.
The MLA Style presented is based on information from the MLA FAQ.
Spheres of Eudoxus:
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 Spheres of Eudoxus.relation by Wolfgang Christian
Know of another related resource? Login to relate this resource to it.