I admit, it's a bit of a stretch to tie sunlight to the end of summer, but for those eager to see the first leaves of autumn fall, here is a sign that summer is in its last legs (if the Back to School shopping mobs didn't tip you off yet):
This photo was taken from the ICE neutrino detector lab at the South Pole last week. The sun has now reached an altitude where it is just 12 degrees below the horizon which means it is official Nautical Twilight there -- the first time they've seen any real sunlight down there in months (since it's their winter.)
It starts the countdown to the first sunrise of the season, which is on the autumnal equinox. (Although as I wrote in the spring there is always some question as to when the first sunrise and sunset really is down there.)
Here is another neat photo from way down under, taken from the ICE Lab in the Amundsen-Scott South Pole Station. A full moon provided a faint glow on the ground as the first inkling of twilight appeared on the horizon.