Education Prize Logo
Science SPORE Prize
November 2011

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

Computer Program Detail Page

Item Picture
written by Todd Timberlake
The Eratosthenes model displays the shadows cast by two gnomons (sticks) at different locations on Earth. For one gnomon, Sun is directly overhead (as would be the case if the gnomon was on the Tropic of Cancer at the summer solstice). The other gnomon is due north of the first gnomon. The sizes of the gnomons are greatly exaggerated for visibility. This simulation can be used to help illustrate how Eratosthenes was able to measure the diameter of Earth using the shadows cast by two gnomons, one situated due north of the other, on a day when the southerly gnomon cast no shadow at all. The distance between the two gnomons (along Earth's surface) can be adjusted. The length of the shadow is given, and this length can be used to determine the angle between the gnomon lines and from that the circumference (and diameter, radius, etc) of Earth. Earth can be hidden to give a better view of the relevant geometry.

The Eratosthenes 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_Eratosthenes.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.

Please note that this resource requires at least version 1.5 of Java (JRE).
View the source code document attached to this resource
Subjects Levels Resource Types
Astronomy
- Astronomy Education
= Curricula
- Historical Astronomy
= History of Astronomy
General Physics
- History
- Measurement/Units
- High School
- Lower Undergraduate
- Middle School
- Instructional Material
= Curriculum support
= Interactive Simulation
Intended Users Formats Ratings
- Educators
- Learners
- General Publics
- application/java
  • Currently 5.0/5

Rated 5.0 stars by 1 person

Want to rate this material?
Login here!


Access Rights:
Free access
License:
This material is released under a Creative Commons Attribution 3.0 license.
Rights Holder:
Todd Timberlake
Keywords:
EJS, Earth, Easy Java Simulations, Eratosthenes, OSP, Open Source Physics, Sun, circumference, gnomon, measure, shadow, similar triangles, triangles, trigonometry
Record Cloner:
Metadata instance created January 2, 2010 by Mario Belloni
Record Updated:
June 6, 2014 by Andreu Glasmann
Last Update
when Cataloged:
January 2, 2010
Other Collections:

ComPADRE is beta testing Citation Styles!

Record Link
AIP Format
T. Timberlake, Computer Program ERATOSTHENES MODEL, Version 1.0 (2010), WWW Document, (http://www.compadre.org/Repository/document/ServeFile.cfm?ID=9756&DocID=1449).
AJP/PRST-PER
T. Timberlake, Computer Program ERATOSTHENES MODEL, Version 1.0 (2010), <http://www.compadre.org/Repository/document/ServeFile.cfm?ID=9756&DocID=1449>.
APA Format
Timberlake, T. (2010). Eratosthenes Model (Version 1.0) [Computer software]. Retrieved October 20, 2014, from http://www.compadre.org/Repository/document/ServeFile.cfm?ID=9756&DocID=1449
Chicago Format
Timberlake, Todd. "Eratosthenes Model." Version 1.0. http://www.compadre.org/Repository/document/ServeFile.cfm?ID=9756&DocID=1449 (accessed 20 October 2014).
MLA Format
Timberlake, Todd. Eratosthenes Model. Vers. 1.0. Computer software. 2010. Java (JRE) 1.5. 20 Oct. 2014 <http://www.compadre.org/Repository/document/ServeFile.cfm?ID=9756&DocID=1449>.
BibTeX Export Format
@misc{ Author = "Todd Timberlake", Title = {Eratosthenes Model}, Month = {January}, Year = {2010} }
Refer Export Format

%A Todd Timberlake
%T Eratosthenes Model
%D January 2, 2010
%U http://www.compadre.org/Repository/document/ServeFile.cfm?ID=9756&DocID=1449
%O 1.0
%O application/java

EndNote Export Format

%0 Computer Program
%A Timberlake, Todd
%D January 2, 2010
%T Eratosthenes Model
%7 1.0
%8 January 2, 2010
%U http://www.compadre.org/Repository/document/ServeFile.cfm?ID=9756&DocID=1449


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 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.

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.

This resource is stored in 3 shared folders.

You must login to access shared folders.

Eratosthenes 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 Eratosthenes Model.

relation by Mario Belloni
Covers the Same Topic As Gnomon Model

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.

relation by Mario Belloni
Is the Basis For Ejs Open Source Eratosthenes Measures Earth Java Applet

changes

tilted by 23.5 degree to simulate topic of cancer
color code the checkbox
add distance = arc length drawing
add text as hints
add top Gnomon checkbox
add shadow checkbox
22June 2012
add Google earth picture
add assessment for learning input fields with feedback for Radius of Earth and Circumference of Earth

credits to Todd Timberlake!
i didn't make this, just remixing to customize it to suit the Wikipedia entry http://en.wikipedia.org/wiki/Eratosthenes
enjoy!

relation by wee lookang

Know of another related resource? Login to relate this resource to it.
Save to my folders

Supplements

Contribute

Related Materials

Similar Materials

The OSP Network:
Open Source Physics - Tracker - EJS Modeling
Physlet Physics
Physlet Quantum Physics