Lecture 5: Matter and Energy

Earth History Time Scale

  • Age of sun & solar system ~ 4.57 Ga (Billions of years)
  • Based on models of stellar evolution and dating of primitive solar system objects
  • Example \rightarrow Carbonaceous chondrites (meteorites)
  • Age of earth ~ 4.54 Ga
  • Based on ages of terrestrial rocks + age of solar system + models of solar system formation
  • Example \rightarrow Acasta Gneiss

The Nebular Hypothesis

  • AKA the Nebular Theory of Solar Nebula Model explains the origin of the solar system
  • Interstellar cloud inherits elements from previous generations of stars

Hypothesis Steps

  1. Interstellar cloud of gas and dust
  2. Rotates and ends up in a shape of flattened disc
  3. High pressure and temperature creates Nuclear fusion in the Sun \rightarrow Solar nebula
  4. Condensation of materials
  5. Accretion of objects
  6. Becomes a larger object
  7. Differentiation
  8. Segregates causing higher density to sink and lower density to rise therefore, it separates from one part to another
  • Example \rightarrow The crust we live on has a lower density because the nucleus sank and the crust rose when the planet was formed.

Solar System

Jovian (outer) planets

  • Huge
  • Gaseous & icy

TerrestRial (inner) planets

  • Small
  • Rocky & metallic

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