One thing I’ve found to be intriguing about night-time photography is the phenomenon of “star trails.” Star trails are created by leaving the camera shutter open for long periods of time to let the light of stars paint across the film. The effect is no different than any other long exposure side effect, with the exception that the movement represented is the rotation of the Earth rather than of the camera. Depending on the composition, this can produce some interesting results. Star trails can be seen in exposures as low as 30 seconds. However the more dramatic trails require exposures of an hour or even longer.
This short sequence of frames shows the progression of star trails in exposures of 5 to 30 minutes.