That's not quite right. While clouds can make the night appear darker, the main reason why night is dark is because the Earth is rotating, and the side facing away from the sun is not illuminated.

Here's a breakdown:

* Earth's Rotation: The Earth spins on its axis, completing one rotation every 24 hours. This rotation causes day and night.

* Sunlight: The sun is the primary source of light on Earth. When the Earth rotates, the side facing the sun experiences daylight, while the side facing away from the sun experiences night.

* Clouds: While clouds can block sunlight, they don't directly cause night. They can make the night appear darker because they scatter and absorb some of the light from the moon and stars.

So, while clouds might make the night seem darker, the fundamental reason for darkness at night is the Earth's rotation and the absence of direct sunlight.