A history of the sky is an installation by the artist Ken Murphy. Every day a camera mounted on the roof of the San Fransisco Exploratorium records time-lapse video of the sky. Each video is then displayed alongside it's chronological neighbour. The result is an elegant and beautiful vision of annual and daily cycles.
The video below shows the work in progress; the first 146 days of the project. The intended aim is eventually show the preceding 365 daily cycles of night and day.