How long? How about six months! From the UK Telegraph:
Click for full-size.
Stunning photographs of landmark captured over six-month period
The spectacular picture shows each phase of the sun over Bristol's Clifton Suspension Bridge taken over a six month period.
It plots the sun's daily course as it rises and falls over Brunel's famous structure, which spans the 702ft (214m) Avon Gorge.
Incredibly, the eerie image was captured on a basic pin-hole camera made from an empty drinks can with a 0.25mm aperture and a single sheet of photographic paper.
Photographer Justin Quinnell strapped the camera to a telephone pole overlooking the Gorge, where it was left between December 19, 2007 and June 21, 2008 - the winter and summer solstices.
His final photograph, called 'Solargraph', shows six months of the sun's luminescent trails and its subtle change of course caused by the earth's movement in orbit.
The lowest arc shows the first day of exposure on the winter solstice, while the top curves were captured in the middle of summer.
Its dotted lines of light are the result of overcast days when the sun struggled to penetrate the cloud.
Gorgeous -- right up there with the Solar Analemma.
