Where does the Earth came from? What is its history?
Earth is part of the Solar System and also a planet. Here are some of the theories of the Earth:
| There are various scientific theories of origin and evolution of the earth
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Nabular Hypothesis
- German philosopher, Kant and French mathematician, Laplace
- Earth, planets and sun originated from Nebula.
- Nebula was large cloud of gas and dust. It rotates slowly.
- Gradually it cooled and contracted and its speed increased.
- A gaseous ring was separated from nebula
- Later the ring cooled and took form of a planet
- On repetition of the process all other planets came into being
- The central region, nebula became sun.
Planetesimal Hypothesis
- Chamberlin and Moulton proposed the theory in 1904
- The sun existed before the formation of planets
- A star came close to the sun.
- Because of the gravitation pull of the star, small gaseous bodies were separated from the sun
- These bodies on cooing became small planet's
- During rotation the small planets collided and form
Gaseous Tidal Theory
- Jeans and Jeffrey proposed the theory in 1925
- Large star came near the sun. Due to gravitational pull a gaseous tide was raised on the surface of the sun.
- As the star came nearer, the tide increased in size.
- Gaseous tide detached when star move away.
- The shape of the tide was like spindle.
- It broke into pieces-forming nine planets of the solar system
