The Variation Of The Earth's Oblateness In Geological Epoch On The Dai Wensai's Nebular Hypothesis

The study of the variation of the Earth's shape on hundred million years scale is an important research area and a basic issue in the study of the Earth's evolution.To define the variation of the Earth's shape,it is necessary to know the variation of the Earth's oblateness in different geological epoch.A relationship among the oblateness,the average radius,the mass and the angular velocity of the Earth can be established or studied from Earth's oblateness formula which is derived from spherical function of potential field theory.Since the formula is derived from statics equilibrium,the oblateness caculated should be the upper limit.The oblateness could also be caculated by formulas derived from spherical function of continuum mechanic Equation,which have relationship among the earth' density,the gravitational acceleration,the angular velocity,the elastic modulus and the Poisson's ratio.This is away from statics equilibrium,thus the oblateness caculated should be the lower limit.Since the changes of the average radius,the mass and the angular velocity of the Earth in the 4.6 billion years epoch of the earth are also essencial to the caculation.This paper summarized about 40 kinds of doctrines of the origin the solar system over the last 300 years.These doctrines are divided into nebular hypothesis and catastrophism.This paper revisioned "Dai Wensai's nebular hypothesis" and speculated the evolution of the first 800 million years after Earth formed.And determined the value or the range of the average radius,the mass and the angular velocity in different geological epoch in "Dai Wensai's nebular hypothesis".In "Dai Wensai's nebular hypothesis" the value or the range of the average radius,the mass and the angular velocity in different geological epoch are inserted into Equation.Through the study of the variation of the upper and lower limit,a pattern of the variation of the Earth's oblateness can be revealed.