The seasons on Earth are caused primarily by the tilt of Earth's axis relative to its orbital plane around the Sun. Earth's axis is tilted about 23.4 to 23.5 degrees from perpendicular to its orbit. This tilt means that as Earth orbits the Sun over the course of a year, different parts of the planet receive varying amounts of direct sunlight at different times
. When a hemisphere is tilted toward the Sun, it experiences summer because the Sun's rays hit that region more directly, resulting in longer days and warmer temperatures. Conversely, when the hemisphere is tilted away from the Sun, it experiences winter with shorter days and less direct sunlight. The equinoxes occur when the tilt of Earth's axis is such that both hemispheres receive roughly equal sunlight, marking the start of spring and autumn
. It is a common misconception that the seasons are caused by Earth's varying distance from the Sun during its elliptical orbit. In reality, the difference in distance is minimal and does not cause the seasonal changes. For example, Earth is actually closest to the Sun (perihelion) during the Northern Hemisphere's winter and farthest (aphelion) during its summer, which contradicts the idea that distance drives the seasons
. In summary, the seasons result from Earth's tilted axis causing the Sun's rays to strike different hemispheres more or less directly as Earth revolves around the Sun, leading to the cyclical changes in temperature and daylight known as the seasons
