1. Have you thoroughly read chapter 3?

2. What was Copernicus' major contribution to astronomy?

3. Modern popular astrology runs directly back to whom?

4. What were the six known planets in Kepler's time?

5. Why did Tycho recommend Kepler concentrate his efforts on Mars?

6. If two objects are moved so the distance separating them is twice as far, how strong is the gravity pulling them together compared to in their previous position?

7. How many perfect or "platonic" solids are there?

8. What did Kepler figure out the shape of planets orbits around the sun to be?

9. What is Kepler's third law of planetary motion?

10. Which great scientist a generation later explained Kepler's laws in terms of fundamental physical principles?