The EJS Venus Phases model illustrates the phases of Venus as predicted by either the Copernican system of the Ptolemaic system (the Copernican system is the default). One window shows Earth, Sun, and Venus on its Copernican orbit. Venus is shown as a disk with the side facing the sun colored yellow (since it reflects the sun's light) and the other side colored dark gray (since that side is dark). Playing the simulation puts all moving objects (Venus and Earth/Sun) in motion. Another window shows what Venus would look at this position, when viewed from Earth through a telescope. A menu option displays another window showing Galileo's drawings of his telescope observations of Venus.  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 Phases of Venus 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_VenusPhases.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).