Glacier National Park

Posted by Ellen

Way, way out in the country, a million miles away from city lights, on a clear night the sky is lit by stars, as we see above at left, in a photo taken in Glacier National Park in Montana. The few small clouds in this starlit sky show up as black blotches that block some of the stars; a completely cloudy night in remote parts of the world is a very, very dark night, too dark to photograph at all.

In the megalopolis, however, clouds actually light up the sky by reflecting urban light pollution to brighten the night dramatically; an overcast night in a big city like Berlin, shown above at right, can be up to ten times brighter than a clear night.