Bright Darkness

How dark is the night sky? Of course, if affected by light pollution, the night sky is not dark at all, but how about if we go to an extremely dark location? There we’ll discover that the night sky is anything but black. In fact, under such very dark skies, once our eyes are dark adapted, we’d still be able to see a person in front of us, and many other things around us. People mistakenly believe that the light of the stars or the Milky Way is what helps us “seeing in the dark”, but the truth is that airglow is in fact responsible of about 67% of what keeps dark skies from being completely dark, followed by 21% caused by the zodiacal light, and a mere 7% comes from scattered starlight. Under these conditions, a puffy white cloud crossing above us will appear as a black spot in the sky, something unthinkable under city lights where passing white clouds are bright and usually of orange color. In the image you can see a scene captured in the high Nevada desert at one of the darkest locations in the US, as one of such “puffy white clouds” was passing by. Notice as well that even faraway clouds near the horizon also appear black, revealing the lack of light pollution all around (the image has NOT been digitally enhanced to produce such effect, of course!).