Earth's orbit showing seasons. Illustration of the Earth's orbit around the Sun, showing how the planet's tilted axis gives rise to the seasons. The angular tilt of Earth's rotational axis varies from 22.1 degrees to 24.5 degrees and back again on a 41,000-year cycle. Currently, this angle is approximately 23.5 degrees and is decreasing. The axial tilt results in the Earth's seasons. Each hemisphere experiences winter when it is pointed away from the Sun, and summer when it is pointed towards the Sun. Counter-clockwise from the bottom, the seasons shown are (for the northern hemisphere), spring, summer, autumn and winter.