The seasons are the parts of the year. The reason for the change of seasons is the tilt of the earth's axis with respect to the orbital plane and the rotation of the earth around the sun. Without an axis tilt, the duration of day and night anywhere on Earth would be the same, and during the day, the Sun would occupy a position above the horizon at the same height throughout the year. Astronomically, the seasons are separated by the moments of the autumnal equinox, the winter solstice, the spring equinox, and the summer solstice. Between the September and March equinoxes, due to the tilt of the Earth's axis, the Northern Hemisphere faces the Sun for less than a day, so the northern latitudes receive less heat and light than the southern ones. In winter, days become shorter, and the position of the Sun at noon is lower than in the Southern Hemisphere, where summer is at that time. Six months later, the Earth passes to the opposite point of its orbit. The tilt of the axis remains the same, but now the Southern Hemisphere is facing the Sun for less than a day making the days shorter and resulting in less heat and light. In the Northern Hemisphere, summer is at this time.