The seasons on Earth are caused primarily by the tilt of Earth's axis, which is about 23.4 to 23.5 degrees relative to its orbital plane around the Sun. This tilt means that as Earth orbits the Sun over the course of a year, different parts of the planet receive varying amounts of sunlight at different times
. Because Earth's axis is tilted, when the Northern Hemisphere is tilted toward the Sun (around June), it experiences summer with longer, warmer days due to receiving more direct sunlight. At the same time, the Southern Hemisphere is tilted away from the Sun and experiences winter with shorter, cooler days. Six months later, the situation reverses, causing the opposite seasons in each hemisphere. The equinoxes occur when both hemispheres receive roughly equal sunlight, marking the start of spring and autumn
. The elliptical shape of Earth's orbit and the slight variation in distance from the Sun throughout the year have minimal effect on the seasons. In fact, Earth is closest to the Sun during the Northern Hemisphere's winter and farthest during its summer, proving that distance is not the cause of seasonal changes
. In summary, the axial tilt of Earth and the consistent direction of this tilt as Earth orbits the Sun cause the seasonal changes by altering the intensity and duration of sunlight received in each hemisphere throughout the year
