Formation of the solar system:
This theory is based on the assvmption that the Sun and all the planets were formed from a huge rotating cloud df interstellar gas and dust. For some reasons, the cloud started contracting. The contraction was hastened by its gravitational
pull. Tlle cloud continued to contract. It also started rotating faster and became disc shaped. More and more'matter contracted towards the centre of the disc, forming the star to be-the new Sun. The temperature of this star rose due to contraction until it started generating its own energy. Revolving around the Sun was a disc of gas and dust from which the planets condensed. In this revolving disc, the lighter elements were thrown towards the periphery and heavier elements concentrated inwards. As the Sun's energy increased, the gas shells around the inner planets were driven off and only cores of heavier elements in the cloud remained. The outer planets were less affected. Finally, the bright star's radiation removed the last of the system's free gases and a mixed array of planets remained. The smaller, solid ones were near the star and the much larger gaseous ones farther away. The Earth was the third planet.