1. The Earth as a Terrestrial Planet
Mass x 1027 gm (6 x 1024 kg)
Size diameter 12,756 km (eq.)
Density – mean 5.5 gm/cm3
Surface % water

2. Why ? – differentiation of elements
Interior
Crust
Mantle
Core
Densities – crust < 3 gm/cm3
-- mantle 3.5 gm/cm3  ?
Very dense core ~ 15 gm/cm3  Fe/Ni
Outer core – molten ( K)
Inner core – solid ~ 7000K
Why ? – differentiation of elements
Rotating molten core produces magnetic field

3. Age Dating of Earth
Radioactive decay -- uranium, plutonium, thorium
U238  Pb206
Th232  Pb208 using known half-life
Rocks on Earth -- newly formed to ~ x 109 yrs
Oldest Moon rocks – 4.5 – 4.6 x 109 yrs

4. Our Active Earth – Plate Tectonics or Continental Drift

6. Consequences– earthquakes, volcanoes, mountain building

7. San Andreas Fault

9. Caused by convective currents in mantle transfers heat to crust

10. The Earth at Night

11. The Earth and Moon as a Double Planet
Mmoon/Mearth = (1/80th)
Rmoon/Rearth = 0.27 (1/4th)
Largest in Solar System

12. Surface Features
Craters
Mare
Highlands

13. Origin of the Moon Sister planet – by fission
Co-accretion – at same distance, same material
Capture – not dynamically feasible
Current theory – massive collision – computer modeling

14. Lunar rocks and soil samples

15. Age Dating Lunar rocks and soil samples
Mare – 3.8 x 109 yrs
Highlands – 4.3 – 4.6 x 109 yrs