Throughout the year, as our small blue planet orbits the Sun, many parts of the Earth experience changing seasons. The warm Spring brings new flowers and young animals. This is followed by a hot Summer filled with vacations, hikes, and outdoor swimming. Following Summer is another warm season known as Autumn, where leaves turn beautiful shades of reds and browns before falling from their trees. Finally, after all of these warmer seasons, comes one that is cold, wet, and dry, known as Winter.
What causes the changes that we see throughout the seasons? Why is the Winter cold, and the Summer hot? Notice that the axis of the Earth is tilted slightly. This causes part of the Earth to lean towards the Sun, while part of it is hidden either beneath the Earth, or above it, causing different parts of the Earth’s surface to receive a different amount of sunlight and heat. As the Earth moves around its orbit, the portion leaning towards the Sun changes. Throughout part of the year, the bottom half of the Earth, or Southern Hemisphere leans out towards the Sun, causing the top half of the Earth, or the Northern Hemisphere to lean away from the Sun. During this time of year, the Southern Hemisphere gets more light and heat, which causes it to be warmer. The effect is that the Southern Hemisphere enjoys Summer. At the same time, the Northern Hemisphere receives less light and heat, making it cooler. While the Southern Hemisphere enjoys Summer, the Northern Hemisphere is in the midst of Winter. As the Earth continues along its orbit around the Sun, the angle that the Earth’s axis tilts changes. Eventually the Northern Hemisphere faces the Sun, and the Southern Hemisphere leans away. During this time of the year, it is the Northern Hemisphere’s turn to enjoy Summer.