Time to
Check Your Solarcans
The northern summer solstice is around one week away. According to Jan Koeman of Philippus Lansbergen Observatory in Middelburg,the Netherlands, that means "it's time to check your solarcans." A solarcan, a.k.a. solargraph, is a pinhole camera made from a soda or beer can lined with a piece of photographic paper. Using such a simple device, it is possible to take extraordinarily long exposures of the daily sun--in this case, six months long. Yesterday, Koeman opened a solarcan he deployed in December, and this is what he found:
Normally, solarcans record the graceful tracks the sun makes across the sky as the seasons unfold--high tracks corresponding to summer, low tracks to winter. In this case, the tracks were interrupted because Koeman deployed his solarcan inside a lighthouse. "I worried that the powerful light from the lighthouse would overwhelm the sun. Luckily our sun is much stronger. However, the fresnel prisms in the lighthouse were chopping up the sunlight."
Got a solarcan? Open it up and submit your images.
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