Understanding the causes of Earth’s seasons is quite challenging and is often misunderstood. Earth’s seasons are caused by the combination of its orbit around the Sun and the tilt of Earth’s axis in relation to that orbit. These factors cause the height of the Sun’s path, as seen from any given location, to change throughout the year. The height of the Sun in the sky determines how much heating will take place.

This Reading provides background information on the underlying concepts in the Activities included in the book, Project Earth Science: Astronomy, Revised 2nd Edition. The Readings go beyond what is found in the background information in the Activities. They can be used as supplementary information for the teacher, or to enhance classroom discussions.