1. The Moon

2. What We See

3. Where We’ve Been

4. The Big Features Oceanus (ocean) Maria (Mare) (sea) Craters
Highlands – bright, cratered regions
Lowlands/Maria – dark, flat regions

5. Other Features
Mountains
Valleys

7. Librations The result of
wobbling of the Moon’s axis toward/away from earth
Relative motion of the observer as Earth rotates
Non-circularity of moon’s orbit (change in size)

8. What’s it made of? I…am…IRON MOON Ti abundance
(blue = lots, orange/purple = less)
But…no dipolar magnetic field. The moon’s weak B field comes from magnetic minerals.

9. The Real Dark Side of the Moon
Note which side the maria are on.
Why only that side?
Anorthosite: igneous rock rich in Ti, Fe
Basalt: fine-grained igneous rock caused by cooling magma

10. Mascons

11. Lunar Prospector measures neutrons from H
Water?
Lunar Prospector measures neutrons from H
1996: Clementine indicates ice in deep craters
1998: Lunar Prospector indicates ice
1998: LP crashed into surface; no water seen
2009: Moon Mineral Mapper aboard Chandrayaan-1 detects water
Chandrayaan-1
(water in blue)

12. LCROSS Launched with LRO in 2008
Atlas-Centaur rocket impactor targeted Cabeus crater
Impactor (2305 kg/10,000mph) produced ejecta plume
LCROSS probe flew through the plume and crashed, relaying data
Data indicate 5% of plume mass was water

13. Where did the moon come from?
4 theories
Fission (moon broke off from earth)
Sisterhood/Co-accretion (formed at the same time)
Capture (moon formed somewhere else but drifted by and ended up in the Earth’s gravitational field)
Giant Impactor (something hit the earth and the resulting material formed the moon)

14. Which one is right? Fission 2. Sisterhood/Co-accretion
Composition of E and M are similar, but not that similar.
Not enough mass in the Pacific Basin to account for the moon.
2. Sisterhood/Co-accretion
See #1 about composition.
E and M should be the same age; M is younger.

15. Which one is right? 3. Capture
E and M are too similar for the moon to have formed elsewhere
Angular momentum of the E/M system isn’t right for the moon having flown in and stopped
4. Giant Impactor
Given a Mars-sized impactor, mass is right
Volatile metals and lack of water on the moon indicate high temperatures in the past.
Simulations show it’s viable (angular momentum OK)
Lower density of moon, lack of iron are consistent with violent impact

16. Whack-a-Moon t=0 Eventually, the cloud becomes a disk and then a moon.
The impactor core becomes the moon’s core
Intense heat is consistent with lack of volatiles and lack of similarity to the earth.
t=24h