Nebular hypothesis
A model of the solar system formation in
which a nebula contracts under the force of
gravity, eventually flattening into a spinning
disk with a central bulge. A protostar forms
at the nebula's center. As matter condenses
around the protostar in the bulge, planets
are formed from the spinning matter in the
disk.
Inner core
Innermost layer of the Earth. Solid made of
iron and nickel. Hottest layer.
Outer core
Layer above the inner core. Liquid made of
iron and nickel.
Mantle
Thickest layer of the earth that sits on top
of the outer core. Made of silicate rocksiron, magnesium and silicon. Solid with
liquid properties.
Crust
Outermost layer of the Earth where we live.
Made up of light rock, basalt and granite.
Continental crust is less dense and thicker
than oceanic crust.
Lithosphere
The crust and uppermost portion of the
mantle. Rigid material.
Asthenosphere
Thin, Slushlike level of the mantle. The
lithosphere floats upon the asthenosphere.
How old is the Earth
according to scientists?
4.6 billion years old
How much of earth’s
surface is dry land versus
Oceans?
29% dry land
71% oceans
Three sources of heat for
earth’s interior.
Meteorite impacts
Weight of overlying materials
Decay of radioactive isotopes