What I liked most about this presentation is that it was centered around astronomy from the bit I could here when I was there. I thought the discussion of Copernicus’ model of the universe was very interesting. I did know previously that people used to think that everything was centered around the Earth. I also thought the Epicycles was a very interesting thing because I had no idea that the Earth moves slightly backwards when it would revolve.
The epicycle idea is outdated and involved planets appearing to move backward, if indeed the solar system was earth-centered. Copernicus model no longer requires epicycles so it fits much better with what we know today.