Earth’s axis of rotation is tilted, as you can see from this illustration ... It is the angle of the Earth's tilt that causes the seasons: spring, summer, autumn and winter.

This problem is the well-known fact that in bygone ages plants existed in high latitudes—as far north as England, for example—whose ... spring reigned on the earth. But there began a series ...

Because of that, different parts of the Earth get exposed to more or less sunlight as the planet rotates around the sun. That's why we have seasons. It's also why the northern and southern ...