What makes earth's seasons?

Answer 1

Earth's seasonality arises from the tilt of Earth's axis of rotation (obliquity) combined with it's orbit around the sun. The Earth's axis of rotation (the conceptual line through the geographic North and South Poles) is tilted at an angle of ~23 degrees relative the Earth's orbital plane.

At the height of the northern hemisphere's summer, the North pole is tilted towards the sun. Not only is the northern hemisphere closer to the sun than the Southern Hemisphere, but it also receives more daylight. The direction of tilt is essentially fixed as the Earth orbits around the sun. Thus, when the Earth has made it to the other side of the sun, the North pole is tilted away from the sun and receives less daylight. This position corresponds to a northern hemisphere winter. Because the South pole is necessarily tilted in the opposite direction of the North pole, the seasons are reversed for the southern hemisphere.