With the revolution of the earth, the position of the constellation will change with (), and with the rotation of the earth, the position of the constellation will also change with ().

"Variable star" means that the position of the constellation is constantly changing every year. Is the constellation moving? That's not true. It is the earth's orbit around the sun that produces the phenomenon of "stars turning around" However, in people's eyes, the sky is a sphere and the stars seem to be as far away from them. They all seem to run on a sphere. We don't feel the earth moving around the sun, but it is like the sun moving between constellations. Why is this happening? This only happens when the earth goes around the sun. When the earth moves in orbit, its position is constantly changing. For example, in Yuan Ye, where people are running by train, only nearby trees and telephone poles can be seen flying upside down, while distant cottages and Woods seem to be marching in parallel. This shows that the near things become more open, the far things change little, and the far and near positions change differently. Astronomers have measured thousands of stars with precision instruments and found many similar facts, which prove that this is a phenomenon caused by the revolution of the earth. Its change is very regular, and it will always be repeated once a year. It proves that the earth rotates once a year.