density and planetary differentiation. planetary differentiation is the separating of a planet into...
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Density and Planetary Differentiation
• Planetary Differentiation is the separating of a planet into different layers due to differences in density.
• Seismic waves tell scientists Earth has four layers of different densities because of their speed.
Density of Earth in g/cm^3
Early Earth
• Scientists infer Earth was formed 4.6 billion years ago.
• When Earth first formed, it was extremely hot!
• The entire planet was a ball of molten elements held together by gravity.
Elements Settled
• While Earth was hot, elements began to settle by density.
• Denser elements sank and less dense elements floated.
• Iron, Nickel, and several other heavy elements (metals) sank to form the inner and outer cores.
• Elements such as Magnesium and Iron silicates (denser rocks) settled in the middle forming the mantle.
• Lighter elements such as Sodium and Potassium Silicates (less dense rocks) settled on the surface forming the crust.
• Liquids (water) formed the oceans above the crust and gasses formed the atmosphere.
Layers vs No Layers
• Scientists can infer that a planet with out layers must have been cooler than Earth when formed.
Which moon(s) of Jupiter formed molten?
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