1. 200 300 400 500 100 200 300 400 500 100 200 300 400 500 100 200 300 400 500 100 200 300 400 500 100 A BCDE

2. The inner planets have this in common

3. What is a small rocky surface?

4. These are the names of the gas giants.

5. What are Jupiter, Saturn, Uranus and Neptune?

6. The largest and most massive planet

7. What is Jupiter?

8. Neptune is very similar in size and color to this planet.

9. What is Uranus?

10. This inner planet once had liquid water on its surface.

11. What is Mars?

12. The gas giants cant let this escape into space because the planets have very strong gravitational pulls.

13. What is their atmosphere?

14. This is the direction Uranus rotates.

15. What is on its side?

16. This force tends to pull together the matter in stars.

17. What is gravity?

18. This is likely to happen to the universe in the future.

19. What is, it will expand forever?

20. A loose grouping of a few thousand stars.

21. What is an open cluster?

22. Saturns rings are made up mostly of these types of chunks.

23. What are chunks of ice and rock?

24. This may indicate that a planet may exist near a distant star.

25. What is a wobble or slight forward and backward motion?

26. This supports the hypothesis that Mars may once have had the conditions needed to support life.

27. What is evidence that liquid water was once present?

28. The four outer planets have this in common.

29. What is they are larger than Earth and are made mainly of hydrogen and helium?

30. This explains why many large optical telescopes are located on mountains.

31. What is so they can be above the atmosphere?

32. A meteoroid that enters Earths atmosphere produces this streak of light.

33. What is a meteor?

34. The mysterious force that may be causing the expansion of the universe to accelerate.

35. What is Dark Energy?

36. Astronomers predicted the existence and orbit of Neptune based on this.

37. What is Neptunes gravitational effect on the orbit of Uranus?

38. Meteroids usually come from these.

39. What are comets or asteroids?

40. One of the conditions required for life on Earth is this liquid.

41. What is water?

42. For this reason, Europa is considered a good place to look for life.

43. What is there may be liquid water under its icy crust?

44. This is the shape of the orbits of most comets.

45. What are long narrow ellipses?

46. The smallest terrestrial planet.

47. What is Mercury?

48. These are two ways Venus and Earth are much alike.

49. What is their size and density?

50. The asteroid belt is located here.

51. Where is between Mars and Jupiter?