Let the camera shoot for a few hours and this is what you get: stars circling the sky, turning into concentric paths around the North Star.
For this image I stacked 230 short exposures, each 50 seconds long, taken over about 4 hours time on July 7/8. My previous blog entry is one of those individual frames. But in this composite, the stars become trails rotating about the pole of the sky, near Polaris, the North Star, here over Num-Ti-Jah Lodge at Bow Lake in Banff. Moonlight provides the illumination and turns the sky blue, just as in daytime, only much dimmer. But the long exposures bring out the colours and make the scene look like daylight, because the light of the Moon is daylight, just reflected first off the Moon’s neutral grey face.
The same frames used to make this still frame composite can also be used to make a time-lapse movie of the circumpolar stars turning.
— Alan, July 14, 2012 / © 2012 Alan Dyer
The Amazing Sky 