Stars don't actually shine on cloudy nights. Clouds block the light from stars, making them appear invisible to our eyes.

Here's why:

* Clouds are opaque: They are made of water droplets or ice crystals that scatter and absorb light.

* Light scattering: When light from stars hits a cloud, it gets scattered in all directions. This means that very little of the light reaches our eyes directly.

* Absorption: Clouds also absorb some of the light from stars, reducing the amount that gets through.

So, while stars are still shining in the sky even on cloudy nights, we can't see their light because it gets scattered and absorbed by the clouds.