The tilt relationship of the celestial sphere and ecliptic
The celestial equator is the enlargement of the earth’s equator to the celestial sphere. Therefore, the celestial equator can be represented by a line fixed on the celestial sphere. The ecliptic is a line connecting the place where the sun is located in the celestial globe for one year. The ecliptic can be represented by a line fixed on the celestial sphere.
Earth is like a tilted, spinning top. The Earth’s axis of spin is tilted 23.5 ° to the axis of revolution.
Therefore, the celestial equator and the ecliptic are inclined 23.5 ° to each other.