light sky

It is only when you're in a forest, at night, during a clear night, that you realise how bright the sky is.

Now I'm talking about when you're away from city lights, perhaps camping...

That's when you realise a "dark" sky is not really dark.

The trees and leaves in the foreground are dark—black! But the dark night sky behind is relatively bright, a dark, almost-colourless deep azure purple.

Ha. The trees and leaves are backlit!