1. Have you thoroughly read chapter 4?

2. How often does Halley's comet return?

3. When was the last close approach of Halley's comet?

4. What was the Tunguska event?

5. Which planet did Velikovsky say came from the Jovian (Jupiterian) system?

6. Why is the surface of Venus so hot?

7. Why does the Earth have fewer craters than the moon?

8. Which planet is most similar to Earth in terms of diameter, mass, and density?

9. Where are most of the comets in our solar system?

10. How do we know Venus is closer to the sun than the earth is?