1. Our Place in the Universe

2. Our Place in the Universe
Cosmology -- the study of the origin, evolution, and eventual fate of the Universe.
Universe -- All matter and energy, including the Earth, the galaxies, and the contents of intergalactic space, regarded as a whole.

3. Where are we right now?

4. Where are we right now?

5. Where are we right now?

6. Where are we right now?

7. Where are we right now?

8. Where are we right now?

9. Where are we right now?

10. Where are we right now?

11. Where are we right now?

12. Where are we right now?

13. Where are we right now?
Solar System – the Sun and all the objects that orbit it.
Star System – consists of a star (sometimes more than one star) and all the objects that orbit it.

14. Where are we right now?

15. Where are we right now?
Alpha Centauri – the Sun’s closest neighboring stars.

16. Where are we right now?

17. Where are we right now?

18. Where are we right now?
Galaxy – A huge collection of anywhere from a few hundred million to more than a trillion stars, all bound together by gravity and orbiting a common center.

19. Where are we right now?

20. Where are we right now?
Local Group -- the group of about 40 galaxies to which the Milky Way Galaxy belongs.

21. Where are we right now?
Nearly every spot of light in this photograph is a galaxy containing billions of stars.

22. TWrT Where are we right now?
Nearly every spot of light in this photograph is a galaxy containing billions of stars.
TWrT

23. Where are we right now? TWrT
Nearly every spot of light in this photograph is a galaxy containing billions of stars.
TWrT
1) How many stars do you think are in the Universe?

24. Where are we right now? TWrT
Nearly every spot of light in this photograph is a galaxy containing billions of stars.
TWrT
1) How many stars do you think are in the Universe?
2) How many Earth-like planets do you think exist in the Universe?

25. Where are we right now? TWrT
Nearly every spot of light in this photograph is a galaxy containing billions of stars.
TWrT
1) How many stars do you think are in the Universe?
2) How many Earth-like planets do you think exist in the Universe?
3) What do you think the probability is that there might be another planet in the Universe that has life on it?

26. Length Scales in the Cosmos

27. Length Scales in the Cosmos

28. Length Scales in the Cosmos

29. Length Scales in the Cosmos
384,000 km

30. Length Scales in the Cosmos
5,906,000,000 km

31. Length Scales in the Cosmos

32. Length Scales in the Cosmos
950,000,000,000,000,000 km

33. Length Scales in the Cosmos
Speed of light – 2.98 x 108 m/s

34. Length Scales in the Cosmos
Speed of light – 2.98 x 108 m/s
Light second – the distance light travels in 1 second (2.98 x 105 km)

35. Length Scales in the Cosmos
Speed of light – 2.98 x 108 m/s
Light second – the distance light travels in 1 second (2.98 x 105 km)
Light year – the distance light travels in 1 year (9.46 x 109 km)

36. Length Scales in the Cosmos
Speed of light – 2.98 x 108 m/s
Light second – the distance light travels in 1 second (2.98 x 105 km)
Light year – the distance light travels in 1 year (9.46 x 109 km)
Note: Light seconds & light years are not time scales. They are distances!

37. Length Scales in the Cosmos
1.25 light seconds

38. Length Scales in the Cosmos
100,000 light years

39. Length Scales in the Cosmos
28,000 light years
100,000 light years

40. Length Scales in the Cosmos
2.5 million light years

41. Length Scales in the Cosmos
TWrT

42. Length Scales in the Cosmos
TWrT
1) Why did astronomers decide to invent the light year?

43. Length Scales in the Cosmos
TWrT
1) Why did astronomers decide to invent the light year?
2) In light years, how large do you think the Universe is?

44. Size in the Cosmos

45. Size in the Cosmos

46. Size in the Cosmos

47. Size in the Cosmos
Planet -- A moderately large object that orbits a star and shines primarily by reflecting light from its star.

48. Size in the Cosmos

49. Size in the Cosmos Moon -- An object that orbits a planet.
Satellite -- Any object that orbits another object.

50. Size in the Cosmos

51. Size in the Cosmos

52. Size in the Cosmos

53. Size in the Cosmos
Star -- A large, glowing ball of gas that generates heat and light through nuclear fusion in its core.

54. Size in the Cosmos

55. Size in the Cosmos

56. Size in the Cosmos
TWrT

57. Size in the Cosmos
TWrT
1) Come up with an analogy to make your younger brother (sister, cousin, etc.) understand how small we are compared to super-massive stars.

58. Size in the Cosmos
TWrT
1) Come up with an analogy to make your younger brother (sister, cousin, etc.) understand how small we are compared to super-massive stars.
2) Come up with an analogy to describe how small we are compared to the whole Universe.

59. Size in the Cosmos Bibliography for photos: