This is because the Earth is a sphere, and the sun's rays are parallel.
Here's why:
* Earth's Rotation: The Earth rotates on its axis, causing day and night. As the Earth rotates, different parts of the planet face the sun, receiving sunlight.
* Sunlight's Path: The sun's rays travel in straight lines from the sun. These rays strike the Earth at an angle, illuminating one half of the Earth at a time.
It's important to note that this is a simplified explanation. The actual amount of Earth's surface that receives sunlight is slightly more complex due to factors like:
* Earth's Tilt: The Earth's axis is tilted, which causes the length of days and nights to vary throughout the year.
* Atmospheric Scattering: The Earth's atmosphere scatters sunlight, which can cause some areas to receive indirect sunlight even when they aren't directly facing the sun.
* Clouds: Clouds can block sunlight, reducing the amount of surface area illuminated.
