That’s not enough to cause significant variations in the Sun’s heating. Although Earth’s orbit around the Sun is an ellipse, its distance from the Sun varies by only about 3%. But the facts don’t bear out this hypothesis. This sounds reasonable at first: it should be colder when Earth is farther from the Sun. Many people have believed that the seasons were the result of the changing distance between Earth and the Sun. With these observed facts in mind, let us ask what causes the seasons. The difference between seasons gets more pronounced the farther north or south from the equator we travel, and the seasons in the Southern Hemisphere are the opposite of what we find on the northern half of Earth. We thus divide the year into seasons, each with its different amount of sunlight. One of the fundamental facts of life at Earth’s midlatitudes, where most of this book’s readers live, is that there are significant variations in the heat we receive from the Sun during the course of the year. Explain how seasonal differences on Earth vary with latitude.Describe how the tilt of Earth’s axis causes the seasons.

By the end of this section, you will be able to:

Animation of earth spinning and seasons