Traditionally, Newton’s laws are directly used to establish the gravitational relationship between two

objects with any type of motion. However, the relationship is mathematically a vector (or vectors), and

it is difficult to solve, especially when the number of objects is greater than 3, the physical relationship

between objects cannot be simply / clearly revealed. It is even more difficult to study the properties of

a gravitational field. With real data verification error less than 3.5%, we found / proved that physical

properties of the ideal circular motion in the gravitational field are essential / can truly reflect the laws

of motion of gravitationally-bound points in the universe. Regardless the mass of the orbiting point /

body, the central mass and its variation determine the physical properties. In this article, we derive,

use real data to verify and discuss the statistic (fixed central mass systems) expressions / properties

of gravitationally-bound points in single or multiple systems in the universe. Strictly speaking, a star

system like our solar system is a variable central mass system. However, since the rate of solar mass

loss is about 1E-12/year, it can be considered as both a fixed central mass system and a variable

central mass system.

**Author(s) Details**

**Jihai Zhang
**Independent Researcher, Canada.

**Ping Tao
**Independent Researcher, Canada.

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