Transcript Our Earth
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 Earth is 71% covered by water – 97% saltwater – 3% fresh water Atmosphere • Blanket of gas • Provides air to • breathe Shields from radiation – 78% nitrogen – 21% oxygen – 1% other 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 Divided into 2 regions Lithosphere Lithosphere •Upper part of mantle •Rigid •Cool and brittle •15km- 300km The Mantle Asthenosphere •Under enormous heat and pressure •Solid rock has the ability to flow (plasticity) •200 km thick The Core Made mostly of iron Makes up 1/3 of earth’s mass Outer Core Dense Inner Core liquid layer 2250 km thick Dense, solid sphere 1228 km thick 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 The Moho *boundary between the crust and the mantle *seismic waves speed up -indicates the mantle is more dense than the crust Shadow Zones *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 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. Larger the mass and the closer together, the greater the force Weight Measure of the strength of the pull of gravity on an object Mass Measured in newtons (N) Depends on the object’s mass and its distance from the earth’s center 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 Movement of the earth around the sun 1 revolution= 365.24 days Perihelion Closest point to the sun January 3 Aphelion Farthest point from the sun July 4 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