revolution
The orbit refers to an object moving along a circle or elliptical orbits around other objects. In astronomy, the revolution in which stars in the galaxy turn against the center of the galaxy is called idle. However, there is not always a celestial body in the center of revolution. For example, if two stars with a small mass difference constitute a binary system, the mass center of the star system exists in the space between the two stars. The subject of revolution is not limited to stars, planets, and satellites, but there are many cases such as dust and gas. In the solar system, the rings of Jupiter, Saturn, and Uranus are in the form of small particles such as dust and ice, and these particles are thought to circulate around the planet. In the case of a black hole, the sucking material forms an annular disk around the black hole, and performs an orbital motion. Assuming that the mass of the gravitational source, which is the source of the orbital movement, is constant, the law of harmony is established that the square of the planetary orbit period is proportional to the cube of the orbital longitude.