The models come in two versions. One set runs in a web browser. Some people reported problems running in Netscape, so a slightly modified version is provided for each model that appears to work correctly in Netscape. In order to run the models in a browser you must have the latest Macromedia Flash plugin installed. In most cases your browser will either already have it, or will offer to fetch it for you from Macromedia. If not, go to www.macromedia.com yourself and download it. It is completely free.
The second set includes stand-alone executables for each animation. These come in versions for Windows and Macintosh operating systems. For the executable versions, you can also run in true full-screen mode by choosing View…Full Screen (or simply ctrl-F) on the menu bar of the application. You can exit full-screen mode by hitting Esc.
You should be able to rescale the window size for all of the animations to whatever size you like. Most of the models appear to run as movies in a VCR or DVD player, and so can be run forward, backward, and paused using the buttons in the top left corner of the screen. Many of the models have features that can be controlled by adjusting the sliders at the bottom of the screens. Adjusting the speed, dimming out various model components, and zooming in/out are the most common features. Just move the slider button by clicking and dragging with your mouse pointer. A couple of the animations (Season Lengths and Ptolemy’s Cosmology, for now) need somewhat finer control, and are therefore adjusted by using the arrow keys of your keyboard.
Several of the models have buttons that allow you to toggle on/off visible trail markers for planets. If you leave trails on for a long time you will in effect be drawing thousands of objects on the screen in every frame, and the animation may well get sluggish. You can click ‘clear trail’ to erase all the previous trail markers and restore the performance of the animation. As far as I know, except for the issue of thousands of trail markers, there is no way for a user to ‘break’ the animations, so feel free to change the adjustments in any way you choose.
Any questions about the animations, and especially any errors or bugs, should be sent to me by . Ideas for additional animations are equally welcome.