1. Give a brief overview of the Aristotles's model of the solar system and the mechanisms used by Ptolemy to keep that model consistent with the observation of retrograde motion.

2. What would the circumference of the Earth have to be if Eratosthenes has measured a shadow length of 10 degrees instead of 7 degrees?

3. What are the principle differences between Galileo and Aristotle's concept of motion and the origin of motion?

4. How did Einstein's new theory help to resolve the dilemma posed by discovering that the orbit of Mercury did not conform to Newton's Laws.

5. Summarize the Shapley-Curtis debate and its implications on the overall size of our Galaxy and the size of the Universe.