Chp. 5 - Earth & Moon



Earth studies lead to models about other planets and visa versa
 

  1. The Earth’s Interior
    1. Seismology - the study of shock waves - seismic waves
    2. they bounce and bend ( reflect & refract)
    3. they change speed

      4.  
  2. Layers of the Earth
    1. How did the Earth become layered?
      1. Gravitational collapse - releases some energy
      2. Natural radioactivity - isotopes
        1. give off E & He atoms (alpha particles)
      3. Rocks are poor conductors of heat, so interior heated and iron melted and sunk to the core.
        1. liquid outer core, solid inner core + rotation -> magnetic field
      4. Differentiation - different densities and melting points (MP)
        1. Refractory series
          1. volatiles - low MP
          2. refractory - high MP
          3. we see this in the moon fewer volatiles more refractories
  3. Plate Tectonics
    1. Alfred Wegener - example of theory change

      2.  
  4. Tides
    1. caused by gravitational attraction between Earth, Sun and Moon (most impt.)
    2. differential forces - two high tides per day
    3. Neap - highest low tides, lowest high tides
    4. Spring - highest high tides, lowest low tides

      5.  
  5. The Atmosphere
    1. Layers
    2. Green House Effect
    3. The Ozone layer problem

      4.  
  6. Van Allen Belts
    1. two regions of charged particles (hi E) trapped by the Earth’s magnetic field
    2. (OH)

      3.  
The Moon

                                (NASA)

I. General Facts

A. average distance - 380,000 km from Earth
B. mass - 1/81 -> 1/6 gravity
C. diameter - 1/4 - big for a moon (6,400 vs 1,700)
D. synchronous rotation (rot = rev)
E. librations - apparent slight turning of the lunar surface ( we see ~63%)
1.changing speed of orbit
2. elliptical orbit
3. 5% tilt
II. Major Features
A. Craters (Lunar Meteorites and the Lunar Cataclysim by B. Cohen)
1. impact features
2. raised rim
3. central peak
4. Copernicus
5. Tycho - rays
B. Highlands 
                        (NASA)
1. light
2. heavily cratered
C. Maria (seas)
1. dark
2. smooth
D. Mts & Valleys
1. mts formed by debris
E. Rilles
1. clefts in the lunar surface
2. collapsed lava tunnels
III. Period
A.synodic - with respect to the earth and Sun - 29.5 days
B. sidereal - with respect to the stars - 27.5 days
IV. Moon Rocks
A. Igneous - formed by cooling magma
1. most common type
B. Sedimentary - formed from weathered rocks
1.ejection material
a) compacted and cemented by ejected materials
2. Breccia
3. very few
C. Mare
1. basalt - igneous
2. vesicular
D. Highlands
1. anorthosites - igneous
2. rare on Earth


V. Craters

A. Impact - most
1. rays
2. raised rims and center
3. superposition
B. Volcanic - not much evidence for crater formation, however there is evidence for volcanism
1. rilles - collapsed tunnels
2. dome
3. vesicular basalt
VI. Formation of Maria
A. large impacts on moon surfaces - ~4 bya
B. interior warm enough to cause flow and fills the impact basin - ~3.8 bya
C. Moon cools - no more flow ~3 bya


VII. Origin of Moon

A. Early theories
1. fission
2. capture
3. co-accretion
B. Current theory - collision-ejection
1. Giant impact of the protoearth threw material into space
a) as a gas
b) as clumps

Chp.5 -Earth & Moon # of 5