3. Planet
Oblate spheroid
Equator

4. Earth’s shadow is curved
Ships disappear as if they are sinking
Tops of mountains are lit before valleys
All appear round

6. Objects weigh more at sealevel at Poles than at equator
We can see horizon is curved in boats and from air and we can travel in one direction and return to beginning
Spaceships and satellites have circled the Earth and mapped it.

10. Lithosphere (crust)
Mass
Oxygen and silicon
Hydrosphere, 70%, hydrogen, oxygen
Atmosphere (troposphere)
Gravity, nitrogen, oxygen

12. High elevation, distorted/deformed bedrock, large relief (big difference from high point to low point), steep
Mid to high elevation, flat sedimentary bedrock, low relief
Low elevation, flat sedimentary bedrock, low relief

13. Earth’s Interior
Inferred properties

14. Interior layers based on:
Believe it is solid iron and nickel
Meteorites from space have far more iron and nickel in them than does earth’s crust.
Core must have a lot more iron and nickel than the surface does
Indicates different chemical composition than surface.

15. Our planet is ‘heavier’ in its orbit than expected.
Earthquake waves tell us earth changes with depth. There are internal layers.
Our planet is ‘heavier’ in its orbit than expected.

16. Magma shows that its hot inside
Uranium, etc. add to interior heat
Inner core is solid and iron and nickel
Outer core is mostly iron and nickel and is liquid
Mantle is mostly solid and the source of minerals
Lithosphere is lightest and solid

18. How did it happen?

19. Solar System
Massive star
Milky Way Galaxy
4.6bya

20. Early ‘proto-earth’
Loose accumulation of material rotates and tightens
Continuously ‘smashed’ by meteors, space debris, comets: accretion
Internal heat flow allowed liquid, dense metals (iron and nickel) to sink to the center
Silicates actually ‘fell’ as rock from sky, creating crust
A ‘planet’ hit early earth, superheating it and creating the moon.

22. Use page 10 Esrt For aspects of interior earth, look at page 10 ESRT.
How do we know? We don’t…..we infer from earthquake behaviors.