What causes the seasons on Earth?
The seasons on Earth are caused by the tilt of the Earth's axis and its orbit around the Sun. The Earth's axis is tilted with respect to its orbit around the Sun at an angle of about 23.5 degrees.
As the Earth orbits the Sun, different parts of the planet receive varying amounts of sunlight throughout the year. When a hemisphere is tilted towards the Sun, it receives more direct sunlight and experiences summer, with longer and warmer days. Conversely, when a hemisphere is tilted away from the Sun, it receives sunlight at a more oblique angle, resulting in shorter and cooler days, leading to winter.
The tilt of the Earth's axis remains constant throughout its annual orbit, which causes the cycle of seasons. During the equinoxes, which occur in spring and autumn, neither hemisphere is tilted towards or away from the Sun, resulting in roughly equal lengths of day and night.