The stars are always moving through the night sky, and these trails show you how much they move over an hour. The center of the spiral is the North Star, which has been used for navigation in ages past because it doesn’t move (much).
Because of the light pollution from the city, I had to take this photo in 30 second segments. Later, in Photoshop, its easy to combine the 120 resulting photos into one (and choosing my favourite foreground bits from various shots as well). The result shows the magic of the evening after all the Canada Day revelers had packed up and gone home.
Everyone came out to enjoy the fireworks, I stayed for the natural wonder.
Photographed in Barrie, Ontario.