Fortune Telling Collection - Horoscope - Is the cycle of the zodiac around the earth one day or one year?

Is the cycle of the zodiac around the earth one day or one year?

The crux of the matter is that because of the rotation and revolution of the earth, we have observed the change of constellation position. Not because the constellation revolves around the earth, resulting in a change of position. This problem is not difficult to understand with daily life experience, just like a merry-go-round, seeing a scene move is not because of the movement of the scene itself, but because of its own rotation.

Because of the earth's rotation, the period of constellation movement is one day, more strictly speaking, sidereal day, instead of the familiar 24 hours, 23 is 56 minutes and 4 seconds, which is also the real period of revolution of the earth. Every other sidereal day, each constellation will complete a movement around the celestial sphere.

Because of the earth's revolution, the annual change period of celestial position is a sidereal year (see the figure below for the principle, the period is 365.5636 days, and the real period of the earth's revolution is slightly different from the tropic year, which is 365.2422 days). Due to the change of the position of the earth relative to the sun, the position of the observation constellation changes at the same time every night every year. Every day, each constellation will be in the same position 3 minutes and 56 seconds in advance, and the first anniversary cycle will be completed in one year.