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 Earth-Sun-Moon Seasons Solar System Stars Laws and Theory

2. This is when the Moon blocks out the Sun.

3. Solar Eclipse

4. This is the property whereby the Moon rotates on its axis at the same rate as it revolves around the Earth.

5. Synchronous Rotation

6. This is when the Moon is at its farthest point from Earth.

7. Apogee

8. This is when the Earth passes between the Moon and the Sun and blocks the light of the full Moon.

9. Lunar Eclipse

10. This is when the Moon is at its closest point to the Earth.

11. Perigee

12. This is when the northern hemisphere has its minimum daylight hours; at or near Dec. 21.

13. Winter Solstice

14. This is when the lengths of day and night are equal.

15. Vernal or Autumnal Equinox

16. This is Earth’s position around June 21 st, when daylight is maximum in the northern hemishpere.

17. Summer Solstice

18. Earth’s 23.5 degree tilt causes this.

19. Seasons

20. This is when there is continual darkness above the arctic circle.

21. Winter (December 21 st )

22. This is the only planet with liquid water.

23. Earth

24. This solar system object was demoted from its planetary status and is now classified as a dwarf planet.

25. Pluto

26. These are bodies of interplanetary debris that orbit the Sun mostly between the orbits of Mars and Jupiter.

27. Asteroids

28. These are icy bodies with highly eccentric orbits that mostly orbit in the outer reaches of the solar system.

29. Comets

30. This is the planet right next door that has a thick carbon dioxide atmosphere and sulfuric acid precipitation.

31. Venus

32. The Hertzsprung-Russel (H-R) diagram classifies stars using their properties of brightness and this.

33. Temperature (Color)

34. This is the cloud of gas and dust in space from which stars are made.

35. Nebula

36. This is the combining of lightweight nuclei into heavier nuclei. This process takes place in the interior of stars.

37. Fusion

38. This is the number of stars in our solar system.

39. One

40. Most of the light emitted by the Sun comes from this region.

41. Photosphere

42. This happens when an object is moving away from the observer.

43. Red Shift

44. This is the change in position of distant objects due to a change in the position of the observer.

45. Parallax

46. This is the movement of a planet in an opposing direction across the sky.

47. Retrograde Motion

48. This is the name of the Moon formation theory that is most widely accepted.

49. Impact Theory

50. This is the theory that states the universe began as a point and has been expanding ever since.

51. Big Bang Theory