That's a good question! It's true that clouds can make it feel darker during the day, but nights are dark because the Earth is facing away from the Sun.

Here's why:

* The Sun is the source of light. It's a giant ball of burning gas that emits light and heat.

* The Earth rotates. It spins on its axis, taking about 24 hours to complete one full rotation.

* Day and night are caused by this rotation. As the Earth spins, different parts of the planet face the Sun (daytime) and then face away from the Sun (nighttime).

So, even if there are no clouds in the sky, the night will still be dark because the Earth is facing away from the Sun.