Ptolemaic animations

The animations I've used in class can all be found here. (If you're using Firefox as your browser, you may need to use the "Netscape" versions on that page). There are a lot of animations to look through, as well as some lecture notes etc. on Ptolemaic and Copernican astronomy. I do recommend that you spend some time exploring it.

If I had been able to get my computer to work on the projector today, I would have asked you to look at the animation of the sun, in particular: you can switch between the equivalent eccentric and epicyclic models. This is important for the issue of "saving the phenomena": if two hypotheses produce identical results, it would seem to be impossible to assert that either was "true."

Also take a close look at the animations of "transformation between a geocentric model and a heliocentric model" for both inner and outer planets. With these animations, you can switch between an epicyclic (Ptolemaic) model, eccentre model (used by some of Copernicus's successors, trying to "re-geocentrize" his astronomy), Tychonic and heliocentric models.

Finally, here there is a quite sophisticated Flash app that allows you to play with all the parameters of a planetary model, and see how it effects the planet's motion in longitude.

Enjoy!