The Sky is Blue - even at night

Something which is important in photography is learning to see as the camera sees. For the camera sees things differently to us. Digital cameras see things differently to film cameras too, so its not just which is better. Its which does what you want better.

Take for instance exposure.

This is a shot of the full moon lastnight as it was rising. The sun had gone down already some hour or so before and the time was already 6:30pm

You can see that the light from the moon is making sky blue.

Yes, just like daylight but only lots less bright.

We don't see it this way because our eyes are not as sensitive in the darkness as the camera sensor is and we can't really accumulate our readings as a camera can when taking a long exposure. So we just see that the sky is hazy. Actually when its darker our eyes don't have colour vision anymore, which further explains whey we only see a glow in the sky rather than the colour.

Looking across the neighbours roof at nearly 10pm the mercury vapor lights of the road are showing on the trees in the distance with their characteristic colour cast and the moon is lighting the sky and clouds just as the sun would do. Making the sky look blue

You can even tune the exposure to see the stars.

as one or two can be seen faintly here. You can rightly guess that full moons aren't good nights for astronomers :-)

Its an eerie light cast by the moon which we can not see as the camera sees.

In learning to master the camera and take control of the images we can get from them we need to grasp that the camera is not completely like our eyes and we need to learn to see as the camera does to get it to produce images that we can see and find pleasing.