<human>:  What causes the change of seasons?
<bot>: The change of seasons is primarily caused by the tilt of the Earth's axis relative to the sun. As we orbit the sun, the hemisphere that is tilted towards the sun has longer days and more direct sunlight, while the hemisphere that is tilted away from the sun has shorter days and less direct sunlight. This is why we experience winter in the Northern Hemisphere while it is summer in the Southern Hemisphere.