This image is of the 2nd Iron Railroad Trestle in Bartlett, at night, just after it got dark. The concentric circles are stars trailing, due to the Earths rotation, centered around the North Star. There was also no visible color to the naked eye in the night sky, but being so close to sunset, the 1+1/2 hour exposure length picked up what was left of the light from the setting sun. All one exposure.