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The Open Source Physics Project is supported by NSF DUE-0442581.

Gnomon Model Documents

This material has 4 associated documents. Select a document title to view a document's information.

Main Document

Gnomon Model 

written by Todd Timberlake

The EJS Gnomon model simulates the shadow cast by a gnomon (the part of a sundial that casts the shadow) over the course of a day for any day of the year and any latitude on Earth. The program gives you the option to use mean Sun (which moves relative to the stars at a constant rate throughout the year) or true Sun (which varies its apparent speed relative to the background stars). The default is to use true Sun. The program also shows the observer's horizon plane on the spherical Earth, as well as the ecliptic and the apparent path of Sun. The Earth View can be set to let Earth rotate or remain fixed

EJS Gnomon 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_Gnomon.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.

Last Modified June 6, 2014

This file has previous versions.

Supplemental Documents (2)

Gnomon for Teachers 

A customizable Gnomon Model that allows teachers to set the display parameters.  The customized simulation is automatically saved with associated curricular in a new jar file that can be redistributed.

Published July 28, 2012
Last Modified July 28, 2012

Gnomon Model: Student Version 

EJS Gnomon Model: Student Version is a simulation for college students. It is distributed as a ready-to-run (compiled) Java archive and has the Shadows and Gnomons activity worksheet pdf built-in.  Double clicking the ejs_Gnomon_ShadowsAndGnomons.jar file will run the program if Java is installed.

Published July 28, 2012
Last Modified July 28, 2012

Source Code Documents

Gnomon Model Source Code 

The source code zip archive contains an XML representation of the Ejs Gnomon Model.   Unzip this archive in your Ejs workspace to compile and run this model using Ejs.

Published August 18, 2009
Last Modified June 6, 2014

This file has previous versions.

OSP Projects:
Open Source Physics - EJS Modeling
Physlet Physics
Physlet Quantum Physics
STP Book