4.1 e arth ’ s f ormation dahs mr. sweet 1 o bjectives explain how most scientists explain the...
TRANSCRIPT
OBJECTIVES
Explain how most scientists explain the formation of our solar system.
Describe Earth’s size and shape and the arrangement of its layers.
List three sources of Earth’s internal heat. Describe Earth’s magnetic field.
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NEBULAR HYPOTHESIS
Most widely accepted model for solar system formation
4.6 billion years ago Cloud of gas and dust
rotating in space Shrank due to pull of
gravity, spinning faster Material collected at
center and became hot.
Hydrogen fusion began creating our sun.
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PLANETISMALS
Frictional, electromagnetic, and gravitational forces formed solid particles of ice and rock.
Eventually formed planets and moons.
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OBLATE SPHEROID
A sphere that bulges in the center.
Shape of Earth. Proof
Measuring the weight of object at several places on Earth.
195 Newtons at Poles and 194 Newtons at equator.
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EARTH’S MEASUREMENTS
Total surface area 510 million square
km 55 continental USA’s
149 million square km is above sea level
Ocean covers 361 million square km
29% dry, 71% wet
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ORIGINAL EARTH
Looked like the moon Same material all the
way thru Collisions created
heat Heat melted iron and
nickel Denser material
moved to the center and lighter materials to the surface
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MANTLE
Thickest of Earth’s layers
Iron, Silicon, and magnesium
Solid High pressure and
temperatures cause it to behave as a liquid.
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OTHERS
Lithosphere Crust and uppermost
mantle More rigid material
Asthenosphere Slushlike layer of
mantle Lithosphere floats on
top Cause of plate
tectonics
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EARTH’S HEAT
Meteorite impacts Compression of
Earth’s interior Decay of radioactive
isotopes Slowly losing heat
Differences in rock, crust thickness, and radioactive rock
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TEMPERATURE AT DEPTH
Above 70 feet temperature remains constant year round
Below 70 feet temperature rises 1o Celcius every 40 meters
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MAGNETIC FIELD North Pole is the
positive pole South Pole is the
negative pole Tilted 11O away from
the poles Hypothesized that
the fluid outer core creates the magnetic field Iron moves through
and electric field creating another electric field 16