Orbits Modeling Of Three Bodies And The Study Of Gravity Convergence Range Of Ideal Celestial Body

A issues about the orbital modeling of three bodies which are based on ideal rigid body. And therefore give rise to a integrate numerical method of three body problem. The gravity convergence of rigid body is studied based on rigid body model too. At first, the approach with classical equation of two-body orbital motion and integral approach as well as its conclusions are summed up, on this basis, an absolute coordinate and the new parameters in which centroid of two body are taken as reference system are used to give the two-body motion equations and analytical solution. After pre-processing method with a two-body motion equation is studied, the numerical solution of differential motion equations for the two-body and results with the classical analytical solution are compared and analyzed. Mass point dynamics is the basic principium of of all the orbit equations. Runge-kutta numerical is used here. The mechanical characteristics for the issues of three-body, the commonly used expression for the equations of motion, analyze the characteristics of several representations are fully studied. In order to facilitate numerical calculation for the three-body motion equation, the absolute coordinate system is selected in the three-body motion equation as the basis for numerical calculation, a complete numerical method is given with focusing on a three-body system, and a numerical method for solving a first-order differential equations which is known as Runge - Kutta method to solve this celestial orbit differential equations of motion, in which some examples are given ,and the results of numerical methods and its application methods are analyzed,as well as it is emphasized in the numerical results to discover and analyze the initial value in numerical calculation and given initial value and the impact of the trend of the calculated results. In the numerical calculation of the analysis process a number of issues are given for which it should pay attention in processing.Another issue in the paper is the study of gravity convergence. Gravity convergence is A set made up of the points where the gravity directions of substances on the surface of the ideal celestial body point to. Several different kinds of mechanical methods such as celestial rotation, tidal force, precession and nutation, etc as well as its corresponding gravity convergence shape and movement characteristics by gravity are discussed. The gravity convergence shape of common ideal celestial body and standard gravity convergence shape which are formed by the nature of the forces from a variety of general objects are given. Gravity dispersion is proposed as well as a limit of amount for the size of the gravity convergence. Some dispersion values of gravity direction for the typical ideal celestial body is given. Some defects and directions which need to be studied go a step further is proposed and discussed in the paper.