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The montage of images above shows the night sky at nautical twilight, when the Sun is 12° below the horizon. In the top right of the frame is part of the constellation Cassiopeia, and the bright star on the left edge is Capella in Auriga. Near the centre, and enlarged in the inserts, is the open star cluster Melotte 20 in Perseus.
Both images are 30-second exposures and are taken with settings of f/3.5 and 400 ISO. Both are taken at 23:00 UT on 2010-05-22.
On the left things are as they should be: A dark, deep blue sky with remnants of twilight on the northern horizon. This image is taken from a few km north of Kelso, Scottish Borders.
On the right we see how things are for so many of us: city dwellers and their local councils illuminate the landscape, mostly with orange sodium streetlights. Much of this light flows upwards into the sky. Added to the natural blue, the result is a bright pink sky through which it is difficult to see the stars. This image is taken from one of the hills of Edinburgh, which are relatively dark places.
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