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Moon

Moon. Lecture 19. The Moon as Seen from Earth. The key features of the lunar surface can be seen with binoculars, a small telescope, or even the naked eye. Craters Maria Highlands. We can see about 59% of Moon’s surface : Libration.

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Moon

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  1. Moon Lecture 19

  2. The Moon as Seen from Earth • The key features of the lunar surface can be seen with binoculars, a small telescope, or even the naked eye. Craters Maria Highlands

  3. We can see about 59% of Moon’s surface : Libration Notice that the Moon appears to nod up and down and wobble back and forth. This apparent motion, called libration, has two causes. First, because its orbit around the Earth is slightly elliptical, the Moon appears to rock back and forth around its north-south axis. Second, because its rotation axis is not exactly perpendicular to the plane of its orbit, the Moon appears to nod up and down in a north-south direction

  4. Lots of Craters • The largest crater on the Moon. • Clavius Crater • 144 miles wide • 16,000 ft deep • about 3000 craters larger than 1km • several millions total • Impact craters on Earth: ~200

  5. Mare Imbrium

  6. Footprint on the regolith

  7. Anorthosite Basalt Breccias

  8. No tectonics Seismometers were set up by Apollo  about 3000 moonquakes per year. These quakes are weak (Richter scale 0.5 to 1.5) and deep (600-800km). Moon is an one-plate world. Thick crust. A small (2-3% of total mass), partially liquid iron-core. No magnetic field.

  9. Sample Returns Six Apollo missions : 382 kg. Three Luna missions : < 0.5kg. • Apollo Mission

  10. Moon Rocks

  11. Late Heavy Bombardment Late Heavy Bombardment = lunar cataclysm = terminal cataclysm Proposed in 1973 by Teraet al. who noted a peak in radiometric ages of lunar samples ~4.0 - 3.8 Ga Sharply declining basin-formation rate between Imbrium (3.85 Ga) and final basin, Orientale (3.82 Ga) Few rock ages, and no impact melt ages prior to 3.9 Ga (Nectaris age)

  12. Clearing of Remnants  Late Heavy Bombardment Gomes et al. (2005, Nature)

  13. Rate of Crater Formation on the Moon

  14. Origin of the Moon

  15. Collisional Ejection Theory

  16. In summary… Important Concepts Important Terms Libration LHB, Lunar cataclysm, terminal cataclysm Mare/Maria • Surface structure of the Moon • Maria • Impact craters • Highlands • Lunar Cataclysm or Late-heavy bombardment • Formation of the Moon • Origin of the Moon • Changing lunar orbit due to tidal friction • Chapter/sections covered in this lecture : sections 10-1 through 10-5

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