Answer:
The two main factors responsible for the occurrence of seasons on Earth are:
1. Tilt of the Earth's Axis: Earth's axis is tilted relative to its orbit around the Sun. This tilt is approximately 23.5 degrees. As the Earth orbits the Sun, different parts of the planet receive varying amounts of sunlight throughout the year. When one hemisphere is tilted toward the Sun, it experiences summer, while the other hemisphere, tilted away, experiences winter.
2. Earth's Orbit Around the Sun: Earth follows an elliptical (slightly oval-shaped) orbit around the Sun. This means that the distance between Earth and the Sun varies slightly throughout the year. When Earth is closer to the Sun (perihelion), it experiences slightly warmer seasons, and when it is farther from the Sun (aphelion), it experiences slightly cooler seasons. However, the tilt of the axis is the primary driver of the seasons.