Earth as a System: Earth: A Unique Planet 2.1 and 2.2 Page 27

Unique facts Only planet with liquid water on the surface Atmosphere has a large percentage of oxygen Only planet to support life

Earth basics Third planet from the sun 4.6 billion years old Mostly made of rock 71% covered with liquid water

Earth from Space A blue sphere with white clouds It is an oblate spheroid Spinning made the polar regions flatten and have an equatorial bulge Relatively smooth

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Earth’s Interior Seismic waves have shown that Earth’s interior is layered

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Layers of the Earth Earlier you learned about crust, mantle, and core

Here are some new terms Look over only

Old TermsNew Terms Crust Mantle Core Outer Inner Lithosphere Crust and upper solid mantle Asthenosphere Flows with plasticity Mesosphere Strong lower part of the mantle Core Outer Inner

Compositional &Structural Zones The Earth’s interior can be divided into compositional and structural zones. Compositional—What they are made of Structural—how they behave

Compositional zones are Crust Mantle Core

Structural Zones Lithosphere Asthenosphere Mesosphere Outer Core Inner Core

Compositional layers Crust thin, solid, uppermost zone of Earth. Crust thin, solid, uppermost zone of Earth. The crust varies from thin on the ocean floor to thick at the mountain ranges

The crust is 10km thick under the oceans Made of basalt Continental crust is between km thick Made of granitic rocks that are less dense than basalt

Crust Thickness

The crust is the uppermost part of the lithosphere

Earth's Internal Layers Andrija Mohorovičić studied seismograms and discovered waves pick up speed at a certain depth Earth is layered Drew a map of the upper boundary of Earth's mantle, Mohorovičić discontinuity

Cool geologists call it the

The Mantle 3000 kilometers thick 2/3 of Earth’s mass Hot iron-rich silicate rocks

Core The center of the Earth Made of iron and nickel

Structural Zones

Lithosphere Narrow layer Includes the Crust and Upper Mantle The Upper Mantle is cool and brittle

The lithosphere is very narrow and is rigid and brittle. It floats on the asthenosphere. The lithosphere is less dense

Asthenosphere Below the lithosphere is a less rigid layer called the asthenosphere It is made of hot, iron-rich silicate rocks Because of the intense heat and pressure it behaves with plasticity It is a solid that flows like a liquid

Thermal convection currents occur here

Convection currents: hot less dense material rises, cools, and begins to fall again.

Mesosphere The strong lower part of the mantle Literally –the middle sphere Lies between the asthenosphere and outer core

The core is still the core.

The core has two parts: the inner and outer cores Outer core: liquid iron and nickel Inner core: Solid iron, nickel, & sulfur

Magnetic Field When a magnetic material rotates with another magnetic material an electric current is generated This current generates an electric field

The Earth's inner core spins within the liquid outer core producing a magnetic field

Magnetosphere

Earth’s Gravity Gravity is the force of attraction that exists between all matter in the universe Newton described his Universal Law of Gravitation The force of attraction between any two objects depend on both their mass and the distance between them

Weight and Mass Weight is the measure of the strength of the pull on an object (a measure of gravitational force) Mass is the amount of matter in an object There is a difference Mass stays the same, weight varies depending on where you are

An object’s weight depends on its mass and its distance from the center of the Earth According to the law of gravitation, the force of gravity decreases as the distance from the Earth’s center increases