The seasons are caused by the tilt of the Earth's rotational axis away or toward the sun as it travels through its year-long path around the sun. The Earth has a tilt of 23.5 degrees relative to the "ecliptic plane" (the imaginary surface formed by it's almost-cicular path around the sun)
Because Earth orbits the Sun, its tilted axis always points in the same direction. For this reason, during the year, different parts of the Earth receive direct rays from the Sun
