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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. Made up of all the earth’s water Earth is 71% covered by water 97% saltwater

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Our Earth

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  1. Our Earth

  2. 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

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

  4. Zones of the Earth Crust Mantle Core

  5. The Geosphere isThe Crust • Thin, solid, outmost zone • Only 1% of earth’s mass • Two kinds • Oceanic crust • Continental crust

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

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

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

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

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

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

  12. 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

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

  14. Gravity Force of attraction that exists between all matter in the universe

  15. 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

  16. 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

  17. The Earth in Space Rotations Revolutions Equinox Seasons Time Zones Solstice

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

  19. Perihelion Closest point to the sun January 3 Aphelion Farthest point from the sun July 4 Revolving Earth Movement of the earth around the sun 1 revolution= 365.24 days

  20. 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

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