新星云假说下地球扁率变化上限及影响因素

Upper Limit Variation of the Earth's Oblateness in Geological Epoch and Impact Analysis on the Dai Wensai's Nebular Hypothesis

地球的形状变化是地球演化研究的基本问题之一。为了确定地球形状的变化需要了解各个地质历史时期地球扁率的变化。根据位场球函数理论导出地球的扁率公式,研究扁率与地球的半径、质量和角速度的关系。基于新星云假说推测地球的半径、质量和角速度的变化量,计算出地球在各个时期的扁率并作为上限并画出曲线,各地质历史时期中地球扁率的真实值应该小于计算的扁率值。地球的扁率自地球形成以来脉动变化的情况下总体趋势在减小。影响地球扁率的因素有平均半径、质量和角速度,分析发现地球形成后5亿年为时间起点计算,到现在(共41亿年)为止平均半径变化对扁率的总影响约为3%,质量变化的总影响没有超过百万分之三。而角速度的减小对扁率变化的贡献超过97%。地球扁率共减少了74.3%。

In this paper,we present the variation of the Earth＇s oblateness in geological epoch and study the factors which affect this variation.The variation of the Earth＇s oblateness can be used to understand the variation of the Earth＇s shape.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 the special function of gravity potential theory.The oblateness and the maximum limitation of the oblateness in a geological epoch can be estimated from the average radius,the mass and the angular velocity of the Earth in the geological epoch.The variation of the oblateness in the geological epoch can be also estimated from the variation of the average radius,the mass and the angular velocity.The real Earth＇s oblateness in various geological epochs should be less than the calculated maximum limitation of the Earth＇s oblateness.Our study shows that the Earth＇s oblateness has had a trend of decrease as a form of pulsatile line since the formation of the Earth.The factors affecting on the variation of the Earth＇s oblateness include the average radius,the mass and the rotation angular velocity of the Earth.After carefully studying and calculating,we find that since 500 million years after the formation of the Earth,the average radius has caused almost 3% of the decrease of Earth＇s oblateness;the change of the mass has caused less than 3 millionth of decrease of Earth＇s oblateness;the angular velocity,the main factor affecting on the oblateness,has contributed more than 97% of the total decrease to the decrease about 74% of the Earth＇s oblateness.