Introduction & Age of Earth

Early molten Earth

From the study of rocks and fossils, Earth is estimated to have originated about 4.6 billion years ago.

  • Kant & Laplace — Nebular hypothesis
  • George Buffon — Planetesimal hypothesis
  • Chamberlin & Moulton — Binary hypothesis
  • Jeans & Jeffreys — Tidal hypothesis

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Nebular Hypothesis

The Nebular hypothesis proposes that the Sun and planets formed from a rotating cloud of gas and dust.

Nebular hypothesis

Planetesimal Hypothesis

Small solid bodies called planetesimals collided and combined to form planets.

Planetesimal hypothesis

Binary Hypothesis

A close encounter between two stars caused material to be pulled and later condensed into planets.

Binary hypothesis

Tidal Hypothesis

Tidal forces from a passing star pulled material from the Sun which later formed planets.

Tidal hypothesis