The Earth revolves around the sun yearly, and when it does, it is tilted. We have hot summers and cold winters because of the tilt. The Earth's movents around the sun causes seasons. When the north pole tilts toward the sun, summer is in the northern hemisphere and winter is in the southern hemisphere. When the north pole tilts away from the sun, its the opposite. When the north pole begins to tilt away from the sun, autumn begins. When the North pole starts to move towards the sun again, spring starts.