2. Key I deas Earth science is the study of: Geology Geology – study of Earth’s surface and interior (minerals & rocks) Astronomy Astronomy – study of the universe & Earth’s place in the Universe Meteorology Meteorology – study of the Earth’s atmosphere and weather Oceanography Oceanography – study of the ocean (waves/currents/shorelines – NOT life in the oceans, that’s marine biology)

3. Origins of the Earth Protoplanet Hypothesis Protoplanet Hypothesis – an educated guess about the origin of the Earth & Solar System based on 6 facts revolveall planets revolve around the sun in the same direction (counter clockwise (CCW) looking from above) nearlythe orbits (paths) of planets are nearly circular nearlyMost of the orbits are in nearly the same flat surface (plane)

4. Origins of the Earth Protoplanet Hypothesis Protoplanet Hypothesis (continued) rotatesthe sun rotates on its axis in almost the same plane and direction that the planets revolve (CCW) mostmost planets rotate in the same direction as the sun (CCW) mostmost planets have moons, and their moons revolve around the planets in the same direction planets revolve around the sun (CCW)

5. What the Protoplanet Hypothesis States 5 billion years ago Great dust/gas cloud 5 billion years ago rotated in space gravity Force of gravity pulled the rotating dust & gas towards the center The cloud shrank and spun faster

6. What the Protoplanet Hypothesis States (cont’d) Compression friction Compression (squeezing) caused friction & heat between the molecules NuclearFusion This heat caused Hydrogen molecules to “mush” together (Nuclear Fusion) This formed the sun, then the remaining dust/gas eventually formed the planets, moons & other small bodies

7. OK, so that’s how the solar system formed…but how did the Earth become what it is today? The answer is… Heat and density differences

8. Layers of the Earth Inner Core solid Inner Core – Earth’s center made of solid iron & nickel Outer Core liquid Outer Core – layer of liquid iron & nickel Mantle Mantle – thick layer of dense rocks Crust Crust – uppermost layer of less dense rocks (it’s thickest below mountains)