3. The Illusion of changing Lunar Size Sequence of photos over Seattle, with the final one a longer exposure

4. Synodic vs Sidereal for the Moon

5. View of the Moon’s Orbit

6. Attributes of the Earth-Moon System

7. Making Eclipse s

8. Anatomy of Solar Eclipses

9. Eclipse Tracks

10. Bailey’s Beads

11. Lunar Eclipses

12. A Lunar Eclipse

13. Share Question In order for a solar eclipse to occur, the Moon must be: a) high in the sky b) near first or last quarter c) near new moon d) near full moon e) over another country

14. Sequence of Lunar Phases

15. Orbital View of Lunar Phases

16. Geometry of Lunar Phases: Earth Perspective

17. Snapshots of Lunar Phases: What doesn’t change?

18. Lunar Rotation

19. Share Question As seen from the Moon, how often does the Sun rise? a) Never. b) About every 24 hours. c) About once per week. d) About once per month. e) About once per year. As seen from the Moon, how often does the Earth set? a) Never. b) About every 24 hours. c) About once per week. d) About once per month. e) About once per year.

20. Prominent Lunar Missions Luna 3: 1959, Soviet 1 st pictures of Moon’s far side Apollo 11: July 20, 1969 Astronauts Armstrong, Aldrin, and Collins first on Moon Apollos 11-17: 1969-1972 Returned ~400 kg of Lunar samples Moon exploration continues to search for water and to study its structure

21. Soviet Commemorative Stamps

22. Dark Side of the Moon

24. Apollo 11

25. Buzz Aldrin

26. Flag on the Moon

27. Lunar FootprintMare Basalt Highland BrecciaHighland Anorthosite

28. Water Ice on the Moon Lunar probes Clementine and Lunar Prospector have provided suggestive evidence for the existence of water ice in permanent shadows near the lunar poles.

29. Water Found on the Moon Four spacecraft recently reported small amounts of H 2 O and/or OH at the Moon: India’s Chandrayaan mission NASA’s Cassini mission NASA’s EPOXI mission NASA’s LCROSS mission The first three measured the top few mm of the lunar surface. LCROSS measured plumes of lunar gas and soil ejected when a part of the spacecraft was crashed into a crater. How much water? Approximately 1 ton of lunar regolith will yield 1 liter of water This false-color map created from data taken by NASA’s Moon Mineralogy Mapper (M3) on Chandrayaan is shaded blue where trace amounts of water (H 2 O) and hydroxyl (OH) lie in the top few mm of the surface.

30. Intensity How was Water Detected? Lunar soil emits infrared thermal radiation. The amount of emitted light at each wavelength varies smoothly according to the Moon’s temperature. H 2 O or OH molecules in the soil absorb some of the radiation, but only at specific wavelengths All four infrared spectrographs measure absorption by water. An infrared spectrum measured by LCROSS (black data points) compared to models (red line) Intensity Wavelengths where water absorbs light model with thermal radiation only model with thermal radiation and absorption by molecules

31. The Big Picture Lunar water may come from ‘solar wind’ hydrogen striking the surface, combining with oxygen in the soil. It may also arrive via meteorite and comet impacts. Both processes are likely. Lunar water may be ‘bounced’ by small impacts to polar regions, forming ice in permanently shadowed craters Similar processes may occur on other airless bodies (e.g., Mercury, asteroids) Water-laden lunar regolith may be a valuable resource, possibly supporting future lunar exploration activities Discovery of water on the moon may support future activities on the lunar surface and beyond. Artwork from NASA / Pat Rawlings.

32. Tidal Forces Tidal forces are a consequence of how gravity from one body acting on a second body varies across that second body. Gravity is a) A vector b) Changes with distance Both Moon and Sun contribute to tides at the Earth (Sun’s tidal force about half of Moon’s) Spring tide - when they add up (Sun, Earth, and Moon aligned at New and Full phases) Neap tide - when tides are at odds (1st qtr. and 3rd qtr. Lunar phases)

33. The Tidal Force

35. Lunar Deformation This is a false-color plot of the Moon’s deviation from spherical shape. Blue is “squashedness” (near the poles) and red is “stretchedness” (mostly at front and rear faces). Based on data from Clementine.

36. Roche Limit Gravity scales like, F G ~ 1/r 2 Tidal forces scale like, F T ~ 1/r 3 Different dependence on distance suggests that tidal forces (although weak) could overcome surface gravity at some close distance, which is called the “Roche Limit” One kind of Roche Limit is to ask how close a moon must come to a planet before the tidal force of the planet lifts a rock off the surface of the moon.

37. The Roche Limit

38. Tidal Evolution of Lunar Orbit

39. Lunar Surface Regolith – layer of rock and dust debris built up from meteoritic impacts Mare – few craters Terrae – many craters Galileo discovered Lunar craters in 1609 Craters: –Reveals properties of sub-surface –Amount of cratering related to surface age

40. Stretch of Lunar Terrain

41. Lunar “Climate” The escape speed from the Moon is 2.3 km/sec, and so it has essentially no permanent atmosphere Moon does keep a transient atmosphere from capture of solar wind and radioactive decay in rocks (composition mainly He, Ne, Ar, and H) Without an atm., the sky is always “black”, and there are large day-night temperature swings, from 400 K (260 F) to 100 K (-280 F) –Earth has a 20 K (36 F) temperature swing on average

42. Crater Formation FEATURES: Impact produces a crater Sprays ejecta Often leaves a rim Sometimes with associated bright rays (radial “spokes”, possibly a consequence of color contrast)

43. Crater Formation

44. Share Question Why are some large crater walls sharp and steep, while others are more rounded? a) different volcanos make different craters b) age differences c) size differences among the impact bodies d) composition differences among the impact bodies e) seismic activity on the Moon

45. The Copernicus Crater

46. Rays

47. Crater Dating Count number of craters, divide by cratering rate, get an age! CAUTIONS: a)Erosion b)Cratering rate can vary over time c)Crater saturation – overcrowding (craters upon craters) NOTE – Erosion can also bias relative numbers of different sized craters, since smaller craters tend to get “erased” faster.

48. Moon’s Interior

49. Origin of the Moon 1)[The Moon is old.] 2)The chemical composition of the Moon and Earth is similar but not identical. 3)Near absence of the iron core in Moon. 4)The Moon’s orbit is inclined to the Earth’s equator, somewhat inclined to the ecliptic, and is prograde.

50. Models Fission Theory: Moon “spun off” from rapidly rotating Earth after iron core formed Binary Accretion Theory: formed as a pair Capture Theory: having formed elsewhere, the Moon was “captured” in a close encounter Giant Impact Theory: collision between Mars-sized body and Earth – debris collects to form our Moon

51. Model Schematics

52. Challenges Fission: –Moon’s orbit inclined to Earth equator –Needed rotation at once per 4 hrs – why was Earth so fast? Binary: –why no iron in Moon? Capture: –Capture difficult (how to slow down?) –Are Earth and Moon compositions too similar? Giant Impact: – favored

53. Artistic Impression of Giant Impact

54. Giant Impact Theory a.Similar composition to Earth because debris contains mantle material b.Different composition owing to the impacting body c.Moon’s orbit being inclined is not surprising d.Body was iron-poor and Earth’s iron core was already formed