Introduction to Planet Earth
Let’s dig a hole to China!
Earth Stats
• The Earth's mass is about 5.98 x 1024 kg.
• Earth is the densest planet in our Solar
System (mass/volume).
• Earth is made of several layers with
different compositions and physical
properties, like temperature, density, and
the ability to flow.
The Composition of
the Earth
The Composition of
the Earth
Crust
•Thinnest layer (5-100 km)
•Two types of crust
•Continental
•Like granite
•Average 30 km
•Oceanic
•Like basalt
(Basalt is denser than granite!)
•Average 5-8 km
The Composition of
the Earth
Mantle
•Extremely Thick! (2,900 km)
•It is too far down to drill
•How do we know what it is
made of?
•Scientists infer based on:
•Pushed up rock
•Ocean floor/molten rock
•What is it like?
•Like the mineral olivine
•Large amounts of iron
and magnesium
www.soc.soton.ac.uk
The Composition of
the Earth
N
Core
•Pretty darn big. (6,856 km)
•(Slightly bigger than Mars!)
•33% mass of the Earth
•Scientists think….
•Made mostly of iron
•Some nickel, sulfur, oxygen
•What is the evidence?
•The particular way seismic
waves travel
•Earth’s Magnetic field
S
The
Structure
of the
Earth
Lithosphere
Solid
Asthenosphere
Viscous Liquid
Outer Core
Liquid
Mesosphere
Solid
Inner Core
Solid
Lithosphere = ‘rock sphere’
Crust and upper rigid part of Mantle
Asthenosphere = ‘weak sphere’
Lower part of Mantle
How HOT is it?
Convection
• Convection (heat) currents
– carry heat from the hot inner mantle to the
cooler outer mantle.
• The mantle gets warmer with depth
• top of the mantle is ~ 1,600° F (870° C)
• bottom of the mantle is ~4,000-6,700° F
(2,200-3,700° C)
• The mantle contains most of the mass of
the Earth
Let’s Make Models of the Earth!
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Inner Core (yellow) diameter 2 cm (4)
Outer core (orange) diameter 6 cm (4)
Mesosphere (red) diameter 11cm (4)
Asthenosphere (brown) diameter 12cm (2)
Lithosphere (sand)
– -after assembly roll edges of asthenosphere
in glue and then sand (1.5mM thick)