1. The Earth, the Moon, and the Sun

2. astronomer What do we call a scientist who studies the planets and stars?

3. 365 1/4 days How long does it take for the Earth to revolve around the sun?

4. 24 hours How long does it take for the Earth to rotate on its axis?

5. the seasons What does the tilt of the earth on its axis cause?

6. More direct rays from the sun cause ________. Slanted rays from the sun cause _______. summer winter

7. Earth is the _______ planet from the sun. third

8. Earth’s surface is constantly _________. Earth’s surface is three-fourths _______. changing water

9. What 2 things make it possible for there to be life on Earth?

10. What is at the center of our solar system? SUN

11. How much bigger is the sun’s diameter than the Earth’s? 110 times

12. 92 - 95 million miles How far away is the sun from the Earth?

13. What is the sun made of? Hot, glowing gases

14. What are the dark patches visible on the sun’s surface?

15. What is the Earth’s only natural satellite? the moon

16. 250,000 miles How far away is the moon from the Earth?

17. How big is the moon compared to the Earth? One-fourth the size of the Earth

18. The moon has extreme temperatures. This means it is very ______ in the daytime and very ______ at night. hot cold

19. Why is it not possible for there to be life on the moon? No air & no water

20. What is the moon’s surface covered with? Craters, mountains, and flat plains

21. We learned about the moon when: Astronauts collected rocks and soil from the moon Astronauts set up experiments on the moon

22. full What is the moon phase when we see all of the lighted side of the moon?

23. What is the moon phase when all of the lighted side of the moon is turned away from us? new

24. When the moon is ________ we see more of the lighted side each night. When the moon is _______ we see less of the lighted side each night. waxing waning

25. During which moon phase do we see only a very small part of the lighted side? Crescent

26. During which phase do we see almost all of the lighted side of the moon? Gibbous

27. During which moon phase is the moon between the Earth and the sun? New Moon

28. Who believed in an earth-centered solar system? Aristotle and Ptolemy

29. Who believed in a sun-centered solar system? Galileo and Copernicus

30. Who built the first telescope? Galileo