1. Which of the following was the most important reason why scientists like Copernicus, Tycho, and Kepler sought a new model to replace the Earth-centered model of the ancient Greeks?

2. Which of the following proved most important to Kepler’s success in creating a more accurate model of the solar system?

3. Which of the following are units that astronomers use to describe the sizes of objects as we view them in the sky?

4. The shapes of planetary orbits around the Sun are called:

5. What was the primary significance of Galileo’s observation of moons orbiting Jupiter?

6. In what way was Kepler’s model similar to Copernicus’s model for the solar system?