Comparison of Solargraphs from Four European Locations

March 22, 2014

Solargraphspor_en_low

Photographer: Maciej Zapior; Maciej's Web site
Summary Author: Maciej Zapior

Solargraphy is a pinhole photographic technique using photosensitive paper to register long exposure images, most often for showing the path the Sun takes across the sky. Because of the sensitivity of this paper, extreme exposure times can be achieved -- some exposures are six months or longer.

Shown above are four solargraphs taken from different latitudes in Europe, covering about 120 days and centered on the winter solstice. They nicely illustrate that the Sun traverses the sky at different elevations at different latitudes. Since exposure times were unequal, only the bottom-most portion of the four solar paths here are comparable. Note that the paths in Bodo, Norway (approximately 67 degrees north latitude) and Oslo, Norway (approximately 60 degrees north) are quite close to the horizon near the time of the winter solstice. In fact, the Sun is actually below the horizon in Bodo for several days about the time of the solstice, but persistent clouds obscured the southern sky for nearly a week. The solar paths for Ondrejov, Czech Republic (50 degrees north) and for Palma de Mallorca, Spain (approximately 39 degrees north) are much higher in the sky in late December. Gaps in the solar curves indicate periods of cloudiness. These solargraphs were taken in four different years between 2008 and 2013.

I'd like to thank Dawid Guzenda, Viggo Hansteen (University of Oslo), Jan Stary (Astronomical Institute in Ondrejov) and Ewa for their help with this project.