Our Earth

Not What You Think  Earth is not a perfect sphere  Oblate Spheroid  Slightly flattened sphere  Spinning on the axis causes the polar regions to flatten and the equatorial regions to bulge

Hydrosphere Made up of all the earth’s water Made up of all the earth’s water Earth is 71% covered by water Earth is 71% covered by water –97% saltwater –3% fresh water Blanket of gas Blanket of gas Provides air to breathe Provides air to breathe Shields from radiation Shields from radiation –78% nitrogen –21% oxygen –1% other Atmosphere

Zones of the Earth Crust Mantle Core

The Geosphere is The Crust  Thin, solid, outmost zone  Only 1% of earth’s mass  Two kinds  Oceanic crust  Continental crust

The Mantle Makes up 2/3 of the earth’s mass Makes up 2/3 of the earth’s mass Divided into 2 regions Divided into 2 regions Lithosphere Upper part of mantle Cool and brittle Lithosphere Rigid 15km- 300km

The Mantle Asthenosphere Under enormous heat and pressure Solid rock has the ability to flow (plasticity) 200 km thick

The Core Outer Core Dense liquid layer Dense liquid layer 2250 km thick 2250 km thick Inner Core Dense, solid sphere 1228 km thick Made mostly of iron Makes up 1/3 of earth’s mass

The Layers were discovered by studying seismic waves: vibrations that travel through the earth.

Two Types of Seismic Waves Primary Waves: P waves Travel through liquids, solids, and gases Travel faster than S waves Secondary Waves: S waves Only travel through solids

*boundary between the crust and the mantle *seismic waves speed up -indicates the mantle is more dense than the crust The Moho

*Locations on the surface where neither S waves or P waves are detected OR only P waves are detected. *Occur because of differences in rigidity Shadow Zones

Magnetosphere Region of space affected by the earth’s magnetic field The Source? Liquid iron in the outer core May be another source

Force of attraction that exists between all matter in the universe

Sir Isaac Newton Law of Gravitation: force of attraction between any 2 objects depends on their masses and the distance between them. Law of Gravitation: force of attraction between any 2 objects depends on their masses and the distance between them. Larger the mass and the closer together, the greater the force Larger the mass and the closer together, the greater the force

Weight Measure of the strength of the pull of gravity on an object Measured in newtons (N) Depends on the object’s mass and its distance from the earth’s center Mass The amount of matter in an object Does not change with location

The Earth in Space

Rotating Earth ► Rotation  Spinning on the earth’s axis  1 rotation = 24 hours  Rotates from west to east

Revolving Earth Perihelion Closest point to the sun Closest point to the sun January 3 January 3 Aphelion Farthest point from the sun July 4 Movement of the earth around the sun 1 revolution= days

The Seasons Caused by changes in the angle at which the sun’s rays strike the earth’s surface If the North Pole is tilted away from the sun, the angle of the sun’s rays on the Northern Hemisphere is lower = winter