The seasons 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 one hemisphere is tilted toward the Sun, it receives more direct sunlight and experiences summer, while the opposite hemisphere, tilted away from the Sun, receives less direct sunlight and experiences winter. For example, around June, the Northern Hemisphere is tilted toward the Sun, resulting in longer, warmer days, while the Southern Hemisphere is tilted away and experiences winter. About six months later, the situation reverses
. This axial tilt causes the Sun's rays to strike Earth at different angles throughout the year. When the Sun's rays hit more directly, the energy is concentrated and temperatures rise; when the rays hit at a slant, the energy spreads out over a larger area, leading to cooler temperatures
. Earth's elliptical orbit does cause slight variations in distance from the Sun, but this has minimal impact on the seasons. In fact, Earth is closest to the Sun during the Northern Hemisphere's winter and farthest during its summer, so distance is not the cause of seasonal changes
. In summary, the seasons result from Earth's tilted axis causing different hemispheres to receive varying amounts of solar energy as Earth revolves around the Sun, leading to the cyclical pattern of spring, summer, autumn, and winter
