1. Bell Ringer
Which two outer planets have the most moons in the Solar System?
Why are Saturn’s rings so bright to us?
How many of the outer planets have rings?

2. OUR MOON

3. Goals for today: Understand the origin of our Moon
What is the Moon made of
Understand what causes the phases of the Moon

4. Nearest Neighbor
Earth-Moon distance 385,000 km
30 Earth diameters

5. Exploration of the Moon
1959
|-- Luna 1 - Jan 2, Flyby
|-- Pioneer 4 - Mar 3, Flyby
|-- Luna 2 - Sep 12, Impact
|-- Luna 3 - Oct 4, Probe
| 1962
|-- Ranger 4 - Apr 23, Impact
| 1963
|-- Luna 4 - Apr 2, Flyby
| 1964
|-- Ranger 6 - Jan 30, Impact
|-- Ranger 7 - Jul 28, Impact
| 1965
|-- Ranger 8 - Feb 17, Impact
|-- Ranger 9 - Mar 21, Impact
|-- Luna 5 - May 9, Impact
|-- Zond 3 - Jul 18, Flyby
|-- Luna 7 - Oct 4, Impact
|-- Luna 8 - Dec 3, Impact
| 1966
|-- Luna 9 - Jan 31, Lander
|-- Luna 10 - Mar 31, Orbiter
|-- Surveyor 1 - May 30, Lander
|-- Lunar Orbiter 1 - Aug 10, Orbiter
|-- Luna 11 - Aug 24, Orbiter
|-- Luna 12 - Oct 22, Orbiter
|-- Lunar Orbiter 2 - Nov 6, Orbiter
|-- Luna 13 - Dec 21, 1966 – Lander
1967
|-- Lunar Orbiter 3 - Feb 4, Orbiter
|-- Surveyor 3 - Apr 17, Lander
|-- Lunar Orbiter 4 - May 8, Orbiter
|-- Lunar Orbiter 5 - Aug 1, Orbiter
|-- Surveyor 5 - Sep 8, Lander
|-- Surveyor 6 - Nov 7, Lander
| 1968
|-- Surveyor 7 - Jan 7, Lander
|-- Luna 14 - Apr 7, Orbiter
|-- Zond 5 - Sep 15, Return Probe
|-- Zond 6 - Nov 10, Return Probe
|-- Apollo 8 - Dec 21, Crewed Orbiter
| 1969
|-- Apollo 10 - May 18, Orbiter
|-- Luna 15 - Jul 13, Orbiter
|-- Apollo 11 - Jul 16, Crewed Landing
|-- Zond 7 - Aug 7, Return Probe
|-- Apollo 12 - Nov 14, Crewed Landing
| 1970
|-- Apollo 13 - Apr 11, Crewed Landing (aborted)
|-- Luna 16 - Sep 12, Sample Return
|-- Zond 8 - Oct 20, Return Probe
|-- Luna 17 - Nov 10, Rover
| 1971
|-- Apollo 14 - Jan 31, Crewed Landing
|-- Apollo 15 - Jul 26, Crewed Landing
|-- Luna 18 - Sep 2, Impact
|-- Luna 19 - Sep 28, Orbiter
| 1972
|-- Luna 20 - Feb 14, Sample Return
|-- Apollo 16 - Apr 16, Crewed Landing
|-- Apollo 17 - Dec 7, Crewed Landing
| 1973
|-- Luna 21 - Jan 8, Rover
| 1974
|-- Luna 22 - Jun 2, Orbiter
|-- Luna 23 - Oct 28, 1974 – Lander
|-- Luna 24 - Aug 14, Sample Return
|-- Hiten - Jan 24, Flyby and Orbiter
|-- Clementine - Jan 25, Orber
|-- AsiaSat 3/HGS-1 - Dec 24, Lunar Flyby
|-- Lunar Prospector - Jan 7, Orbiter
| 2003
|-- SMART 1 - Sep, Lunar Orbiter
| 2007
|-- Chandrayaan-1 - Sep, Lunar Orbiter
|-- Chang'e 1 - Sep, Lunar Orbiter
|-- Kaguya (Selene - ) Lunar Orbiter
| 2008
|-- Lunar Reconnaissance Orbiter - Oct, Lunar Orbiter
| 2011
|--GRAIL – Gravity Recovery and Interior Laboratory – Dec 2011 – Lunar Orbiter
Luna Program (space is hard)

6. By the numbers 3500 km diameter 0.01 Mass of Earth 1/6 Gravity
3.3 g/cm3

7. Moon versus Asteroids In what way is the Moon like a planet?
In what ways is it more like an asteroid?

8. Two terrain types
Highlands
Lowlands-Maria

9. Lunar Highlands Geochemically different
Crust is thicker about 100 km thick vs 40 km below near side.
Lots of craters

11. Maria
Dark
Lowlands
Nearside
Thin crust
Lava plains

12. Moon’s Topography

13. Moon’s Internal Structure

14. Asthenosphere

15. Moon’s Origin

16. Moon’s Origin Hypothetical Models
Fission (Just decided to break off one day)
Co-Accretion (Both formed in same area)
Capture (A captured asteroid)
Giant Impact (Blasted off of Earth)

17. Observations (Not inferences)
Moon is Earth’s companion
Moon’s composition is similar to Earth’s

18. No water. No atmosphere. Why?
Moon’s bulk chemical composition is not exactly like Earth:
Moon poor in volatiles (water, gasses, etc).

19. Small Lunar Core: Why?
Moon rich in rocky material but iron poor.

20. Origin of the Moon Hypothetical Models Fission Co-Accretion Capture
Giant Impact
Observations
Moon’s average composition is like Earth’s and unlike meteorites
It is water and volatile poor
Moon is rich in most rocky elements
But Moon is iron poor

21. Giant Impact Proposed by Hartmann and Davis, 1975
Cameron and Ward, Thompson and Stevenson
Debated in Kona, “most successful meeting in planetary science” - Drake
Modeled (Melosh, etc.) and published 1986

23. Giant Impact A good example of science in action

24. Earth, Sun, and Moon model

25. Lunar Eclipses

26. Solar Eclpises

27. Annular Vs. Total

28. Moon = Only other body in Solar System besides Earth that Humans have been on.

29. OTHER MOONS IN THE SOLAR SYSTEM

31. MARS’ MOONS Mars has two moons.
We think both were asteroids captured by Mars.
Very small, very insignificant.
Phobos will one day be ripped apart by Mars’ gravity, giving Mars a small ring.
Deimos will eventually escape Mars’ hold on it and fly away.

32. Jupiter’s Moons Callisto Ganymede Mercury Europa Io
NASA: Galileo images of Jupiter’s Moons

33. Ganymede

34. Ganymede
. Biggest Natural Satellite in the Solar System
. Cratered

35. Light and dark terrain

36. tectonism

38. Europa

39. False color
What do you notice?

40. Upwellings? – Water seeping up through cracks.

43. Next NASA flagship mission: Europa Clipper Orbiter (maybe lander too…) launch 2022 At Europa 2026!

44. Europa has a liquid ocean under an icy shell

45. Io

47. Io is covered in volcanoes
Why?

49. Layer of magma, globally, under crust.

50. Comparison of Jupiter’s Moons

51. Moons of Jupiter Satellite Size Density Composition Craters
(km) (g/cm3) (Ice%) ____________________________________________
Io % 0
Europa % Few tens
Ganymede % Many
Callisto % Saturated
________________________________________________

52. Why are they so different?
What are the two main differences?
Composition
Density
Color
Internal energy – Affects surface features
Surface age
Number of craters
Active geologic processes

53. Composition

54. Gasses and water couldn’t condense until Jupiter
Ancient Frost Lines
Gasses and water couldn’t condense until Jupiter

55. Ancient Frost Lines Mini nebula at Jupiter??
Inner gas/water-poor, outer gas/water-rich
Jupiter like a protosun? Io
Europa
Ganymede
Callisto
1000°K
400°K
300°K
200°K
100°K
Jupiter

56. Internal Energy – Surface Features

57. Tides Mass pulls on other mass
Think of Earth’s tides – from the Moon pulling on water
Ivaschenko

58. Tides
If satellites are close enough, planets can even pull on the rocks and interiors
If the distance changes, rocks slide past each other, causing friction and heating

59. Tidal Heating of Galileans
JUPITER PULLS ON ORBITS – KEEPS THEM OVAL SHAPED
Bodies sometimes close to Jupiter, sometimes far away
Causes heating and melting

60. SATURN’S MOONS

61. 20 Rs
60 Rs
216 Rs

62. Ring Shepherd Satellites
Epimetheus
116 km Epimetheus, 200 km Janus
Janus

63. Ring Shepherd Satellites
Pandora
141 km Pandora, 3 km Methone (is between Mimas and Enceladus)
Methone

64. Ring Shepherd Satellites
Pan-!
141 km Pandora, 3 km Methone (is between Mimas and Enceladus)

65. Iapetus

66. Mimas

68. Tiny Enceladus
Plasma Flow

69. Bright Enceladus
In Greek mythology Enceladus was a Titan who was defeated in battle and buried under Mount Etna by Athena.

70. Enceladus

71. Enceladus Water is gushing out of south polar fractures!
Tiny body should have a cold interior

72. Water in contact with rocky core

73. TITAN – most like Earth?

75. What did we know?
Nitrogen-rich atmosphere!
Also lots of methane

78. Rounded cobbles in river bed!
Karkoschka zoom in:
Erosion
Rounded cobbles in river bed!

79. Mountains In long belts and isolated blocks Heavily eroded
SIR-C/X-SAR of Tibetan plateau.

80. Like linear dunes on Earth

81. Methane Seas of Titan

82. Seas of Titan
Glint off sea surface