Why does it get foggy and yellow when there is pollution ? Why would pollution on earth change the color of sky water ? The answer is the color of the sky is reflection from earths oceans. This is why at night you don’t see blue up there. Instead the light comes in from the moon stars, and planets. What would happen if you shine a powerful light to the night sky. Would you see blue? No. Because most of the earth surface where you are is dark at night. So no blue reflections.