The main cause of seasons on Earth is the tilt of the Earth's axis. Here's how it works:
1. The Earth's axis is tilted about 23.5 degrees relative to its orbit around the Sun.
2. This tilt means that as the Earth revolves around the Sun, different parts of the Earth receive varying amounts of sunlight throughout the year.
3. When a particular hemisphere is tilted towards the Sun, it experiences summer because sunlight is more direct and concentrated, leading to warmer temperatures.
4. Conversely, when that hemisphere is tilted away from the Sun, it experiences winter due to the sunlight being more spread out and less intense, resulting in cooler temperatures.
5. The equinoxes occur when neither hemisphere is tilted towards or away from the Sun, leading to nearly equal amounts of daylight and darkness, marking the start of spring or autumn.
In summary, the tilt of the Earth's axis is the fundamental reason for the changing seasons as different parts of the Earth receive varying amounts of sunlight throughout the year.