Question

Explain the events leading to origin of earth by Big Bang Theory.

Answer 1

The Big Bang Theory explains the origin and expansion of the universe; the formation of the solar system and Earth followed later.

1. The universe began in a very hot, dense state and expanded; as it cooled, galaxies formed. 
2. The Milky Way formed, within which a cloud of gas and cosmic dust the solar nebula collapsed under gravity and began to rotate. 
3. The cloud flattened into a disc, with the Sun forming near its centre and material in the surrounding disc gathering into planets. 
4. Early Earth was extremely hot and largely molten. As it cooled, a solid crust formed, followed by the atmosphere and, after further cooling, liquid water. 
5. Volcanic activity released gases and water vapour; condensation and rain contributed to the formation of oceans. 

Earth formed from material in the solar nebula and gradually cooled into a planet with a crust, atmosphere and hydrosphere.