1. THE VIEW FROM EARTH

2. EARTH IN MOTION

3. 1.Rotation: Period = 24 Hours 2. Revolution: Period = 365.2564 Days 3. Precession: Period  26, 000 years 4. Motion of Solar System relative to nearby stars 5. Solar System orbits center of Milky Way: Period  230 million years 6. Milky Way Moves within Local Group ‘Swarm’ 7. Local Group partakes of Expansion of Universe

4. North Pole Rotation 750 mi/hr at State College!

5. To Sun Night Day Twilight Zone Night & Day

6. One way to get rotation period...

7. Revolution 1 AU View from above Earth’s north pole. 67,000 mi/hr!

8. Orientation of Earth in Space Orbit Plane (‘Ecliptic Plane’) Equatorial Plane North I I = 23.5 o

9. Gravity Top Precession

10. Gravity of sun & moon try to change direction of Earth’s rotation axis – Earth Precesses.

11. Rotation axis fixed in space – over short intervals. p. 20

12. Motion relative to nearby stars p. 22

13. Orbit about center of Milky Way 500,000 mi/hr p. 23

14. M31 Milky Way 180,000 mi/hr Motion within Local Group 3,000,000 ly

15. Collision of Milky Way & Andromeda Spiral (M31)

16. Expansion of the Universe

17. p. 24 ‘Raisin Cake’ Model Before Baking After Baking

18. LATITUDE, LONGITUDE & ALL THAT

19. The Meaning of Latitude Earth N L L  Latitude

20. 66.5 o N 23.5 o N 90 o N 0 o N Terminator p. 33

21. Longitude p. 33

22. Earth’s Grid State College, PA Latitude = Longitude = p. 33

23. CELESTIAL SPHERE: A MODEL OF THE SKY

24. RISING & SETTING

25. Earth seen from above north pole 4 hours later

26. Meridian A locale in the northern hemisphere.

27. Rising or setting? (Looking west or looking east?)

28. Anglo-Australian Observatory South Celestial Pole Circumpolar Stars

29. 35 o N Lat Circumpolar p. 33

30. THE SKY & YOUR LATITUDE

31. Z A A = latitude of observer

33. At a Mid-Northern Latitude

34. At the North Pole

35. At the Equator

36. Position of NCP relative to stars shifts due to precession.

37. DIFFERENT STARS IN DIFFERENT SEASONS

38. November September July

39. CONSTELLATIONS

40. “Traditional”: Person, animal, object depicted by pattern of stars. e.g., Cygnus – Swan Ursa Major – Big Bear Scorpius – Scorpion Boötes – Herdsman Greco-Roman Tradition Antlia – Air Pump 18 th Century p. 28

42. Orion - Hunter “Modern” (from 1928): Well-defined region of celestial sphere. * 88 modern constellations.

43. Winter Triangle

44. Orion

45. Milky Way p. 30