The earth revolves around the sun in an elliptical orbit. It completes its revolution in approximately 365 days. The axis of the earth is tilted towards the plane of its orbit at an angle of 23.5 degrees. The axis always points towards the same fixed point in space: the polar star. Due to these arrangements seasons are formed and the length of days and nights vary alternately. Due to the inclination of the earth, the sun’s rays fall on different parts of the earth with varying intensity, making up for different seasons in different hemispheres.