Planet Oblate spheroid Equator

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

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.

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

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

Earth’s Interior Inferred properties

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.

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.

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

How did it happen?

Solar System Massive star Milky Way Galaxy 4.6bya

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.

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.