Chapter 4 • Nebular Hypothesis • Hypothesis for the Origin of our solar system…..4.6 bya, a rotating cloud of gas/dust shrank under its own gravity …..began rotating faster, thus forming a center • Con’t. • That center compressed and became so hot that hydrogen fusion occurred. Thus our sun was born • Earth formed out of condensing solid particle of ice and rock Earth’s Shape • Oblate spheroid • Flattened at the poles and bulging at the equator • Why? Due to earth’s spinning motion Earth’s Structure • Earth’s layers • • • • Inner core (solid) Outer core (liquid) Mantle (solid) Crust (outermost layer) Earth’s Heat • Earth is heated from within • Earth is slowly losing heat • Compressed inner layers are very hot (6000oK!) • Radioactive decay of isotopes • Earth’s crust in thinner in certain areas • Certain types of rock retain heat better than others • Earth’s magnetic field • Why compass’s point north!!!!! • The North pole attracts while the south pole repels • Theory is that the field is created by moving liquid iron in the outer core Because of Earth’s magnetic field… • Auroras!!! • Solar Wind (flow of electrically charged particles) comes into contact with Earth’s magnetic field and a bright, colorful light is created • Aurora Borealis!!!!!