2. Earth Facts:
• circumference around the poles is 40,007 km
• circumference around the equator is
40,074 km
• Earth is NOT a perfect sphere… it is a oblate
spheroid, a slightly flattened sphere
• Earth’s mass is approximately 6.0 x 10 24 kg
• Earth’s average diameter is 12,735 km
• Difference between the height of the tallest
mountains and the depth of the deepest
ocean trenches is only 20 km
3. Layers above the Earth
• Hydrosphere: all of the water that covers the
Earth
• Atmosphere: blanket of gases that surround the
Earth; 78% Nitrogen; 21% Oxygen; The rest (1%)
combination of argon, carbon dioxide heliu
and water
• Atmosphere is
divided up into
5 regions
5. Layers inside the Earth
Crust: The thin, solid outermost zone
of the Earth
• Makes up only 1% of Earth’s mass
• Oceanic Crust: crust under the oceans
• Only 5km to 10km thick
• Continental Crust: crust that makes up the
continents
• 15km to 80km thick
• Thickest beneath high mountain ranges
6. Layers inside the Earth
Mantle: Zone of rock nearly 2,900km thick
Makes up almost 67% of Earth’s mass
Layers of the Mantle:
Lithosphere: uppermost part of the mantle and
the crust above it; cool and brittle. The
boundary between the crust and mantle is
referred to as the MOHO
Asthenosphere: solid rock with the ability to flow
due to heat and pressure (plasticity)
Mesosphere: increasingly dense and solid rock
layer (aka “Lower Mantle”)
7. Layers inside the Earth
Core: Center of the earth made up mostly
of iron
Outer core: dense liquid layer about
2,250km thick
Inner core: dense solid layer about 1,228km
thick
Together the inner and outer core make
up about 33.3 % of Earth’s mass
8.
9. How Do We Know?
Seismic Wave Studies
P and S
Waves
Liquids and
Solids
We will talk more about
seismic waves when we
study Earthquakes!
12. The Earth’s Gravity
Sir Isaac Newton’s Law of
Gravitation: The force of
attraction between two
objects depends on the
mass of the objects and
the distance between
them.
Weight: A measure of the strength of the pull of
gravity on an object
Weight and Mass are NOT the same….
EUREKA !
13.
14. The Earth is not perfectly
round it is slightly wider
around the Equator
So… a person standing at the
Equator is farther from
the center of the Earth
than a person standing at
the North Pole.
The person at the Equator
will weigh less because he
is farther from the center
of the Earth.
15. The Movements of the
Earth
How fast is the 0.5 km/sec Called: Time it takes for Earth
Earth spinning? ROTATION to ROTATE once on
it’s axis: 24 hours
How fast is the 30 km/sec Called: Time it takes for Earth
Earth revolving REVOLUTION to REVOLVE once
around the around the sun:
Sun? 365.24 days (1 year)
How far is the 147,100,000km Called:
Earth from the Perihelion
sun when it is
CLOSEST TO
IT?
How far is the 152,600,000km Called:
Earth from the Aphelion
sun when it is
FARTHEST
FROM IT?
