The apparent path of the Sun’s motion on the celestial sphere as seen from Earth is called the ecliptic. The ecliptic plane is inclined 23.5° with respect to the plane of the celestial equator since the Earth’s spin axis is tilted 23.5° with respect to its orbit around the sun. The ecliptic plane intersects the celestial equatorial plane along the line between the equinoxes. The tilt of the Earth's axis with respect to the ecliptic is responsible for Earth’s seasons. Rainfall, summer and winter are the three man variation of the season. So, if the equatorial plane is not inclined to its orbit, then there will be no seasonal variations.