What causes seasons to change throughout the year?

Earth's seasons are caused by the planet's axial tilt of about 23.5 degrees relative to its orbit around the Sun. As Earth travels around the Sun over the course of a year, this tilt means that different hemispheres receive more direct sunlight at different times. When the Northern Hemisphere is tilted toward the Sun, it experiences summer because sunlight strikes at a more direct angle and days are longer. At the same time, the Southern Hemisphere experiences winter. Six months later, the situation reverses. Contrary to a common misconception, seasons are not caused by Earth's distance from the Sun, as Earth is actually slightly closer to the Sun during Northern Hemisphere winter.