You’ve probably noticed that it gets warmer in summer and colder in the winter. This change happens every year. It happens because the earth tilts back and forth as it goes around the sun. During the summer, the earth tilts toward the sun, which makes half of the earth hotter — this is what we call summer. During the other half of the year, the earth tilts away from the sun, which makes that half of the earth cooler. We call this winter.

Did you know that different parts of the world have winter and summer at different times of the year? In the northern half of the world (such as North America and Europe), winter happens during the months of December, January and February. In the southern half of the world (such as South America and Australia), winter happens during the months of June, July and August. Winter happens at different times because the top and bottom halves of the earth tilt away from the sun at different times of the year.