4. How do Astronomers measure distances
7. What are satellites and space probes
9. How do humans survive in space
10. What are the Earth_s motions
13. How does the earth orbit the sun
15. What is known about Earth_s moon
16. Why can we see only one side of the moon
17. What are the phases of the moon
22. What are the features of the sun
23. What are the inner planets
24. What are the outer planets