GEOLOGY - Earth and Origin of Earth

We know that the Earths place in the universe is indeed small , and compare to the other planets , it is not too large in size. Even inspite of that , Earth is a sizeable body , with a polar diameter of about 12, 714 km , and equatorial diameter of 12,756 km , and thus has an equatorial bulge. The circumference of the earth is about 40, 000 km , and it's surface is area is about 510 million square km. Its volume is about 1042 billion cubic km , and it's mass is about 5.97 into 10 is power 21 tonnes. In shape , the earth is like an oblate spheroid. That is , with the exception of a slight flattening at the poles , the earth is nearly spherical or ball shaped. The minor flattening or earth's equatorial bulge is caused by the centrifugal force of rotation. This midriff bulge of earth is very minor in the sense that on a model earth of 8 metre in diameter , one could hardly see it , for this slight protuberance would amounts to less than 2 cm. On the same scale ,  our highest mountains would rise to about 1/2 cm above the sea level.
But deposit it's relatively unassuming statistics , ours is a most fortunate planet the seems "just right" in many ways. Its general size , composition , daily rotation and it's distance from the sun perhaps provides optimum conditions for the development and continuation of life. The fact that earth is the only planet that appears to have a large supply of water , has undoubtedly had much to do with this. Earth's No. 3 position is also very important , for at about 150 million km from the sun , it is neither too near it , nor too far off it. Has it been very near to the sun like mercury , the heat and temperatures would be enormously high and seas would have literally boiled away. On the other hand , if it would have been too far away like Pluto , there would be incredibly cold , making life impossible. Earth's average of temperature of 14 degree celcious appears to be "just right" for life sustenance.

Origin of the Earth :- We human beings have been living on the Earth for a very long time. During the development of science on the Earth, and in his search to know the unknown, man has thought to a lot to know as to how Earth was born. Where from it come ? This question , which has kept the minds of the cosmogonists agitated for a long time , can not be answered with certainty , even till to day.
Infact , the problem is not only to predict the origin of the Earth , but is to predict the origin of the entire solar system , of which , Earth is an important member. Therefore , any speculative suggestion made on the mode of this origin , must satisfy all the known facts about our solar system , and it must agree quantitative with all the known physical and chemical laws.
Intact , our solar system is a well ordered system of planetary bodies , and is not just a haphazard arrangement. This fact may indicate a common origin for all the components of this system. Hence , the entire solar system should be viewed as a whole together , abducted any prediction made regarding the origin of any of its component should be satisfy all the known characteristics of the entire solar system as a whole.