Earth

Models

• Model is a representation of an object or event.

Shape of Earth• Earth is “fat” at the center!• It is not a circle or sphere!

Oblate Spheroid

How do we know the Earth is round“ish” ?

• When I look at the sky the sun rises and sets!• Stars appear to rise and set!• When I look in the distance it is flat!

Prove it how do we know it’s shape.

Proof

• Sinking Ship Theory – • Back in the day (a Tuesday-btw) when ships would

leave port the families would watch the ship sink in the distance, only to find out that they were fine!

Proof• Gravity – • Because Earth is not perfectly round the

amount of pull the Earth has (gravity) varies.

• At the poles you weight more

• At the Equator you weight less

Proof

• Pictures – • Our best evidence is pictures from space!

Proof

• Shadows on the moon (eclipse) – • As the Earth blocks the sun a shadow appears

on the moon.

Structure of Earth• Lithosphere– Crust and rigid mantle ends at the MOHO.

• Hydrosphere– All liquid layer on the surface of the earth.

• Atmosphere– Shell of gas around the surface.

Layers of Earth

• Lithosphere: Crust and rigid mantle ends at the MOHO. 2.7-3.0g/mL 5-60km deep.

• Mantle: Asthenosphere or plastic mantle 60-2900km deep.

• Outer Core: 2900-5100km deep made of liquid iron and nickel.

• Inner Core: 5100-6300+km made of solid iron and nickel.

Layers of the Earth

ESRT ChartEarth’s Layer Temperature

Range (oC)

Pressure Range

(million ATM)

Density Range(g/mL)

Depth Range(km)

Crust (lithosphere)(Solid)

Mantle(Solid”ish”)

Outer Core(liquid)

Inner Core(Solid)