Stormcloud Captures Sun

Enthusiasts of curling, beer, and solargraphs will welcome the 16-ounce cans of Bonspiel Noir from Stormcloud Brewing Company in Frankfort, MI. On the 2025 June solstice I recovered a solargraph from a Bonspiel Noir can that served as a pinhole camera, with the featured sun intersecting the straight-edge gnomon of a sundial.

The color-adjusted image shows the solar arc through the seasons, from the December solstice to June solstice. When it is paired with a panorama photo, you can see how the lower arcs silhouette the leafless branches of the tree in winter, while the higher arcs are more obscured by the leaves in summer.  A faint shadow along the gnomon suggests the sundial got bumped out of alignment at some point in the six-month exposure.

A solargraph has similar distortion as a panorama photo. Though the straight edge of the sundial's gnomon appears curved, each arc of the sun intersects the gnomon at a perpendicular angle.

While visiting Stormcloud in August 2024, I could see the constellation Corona Borealis (CrB) from their outdoor seating area. I'd been taking nightly photos of the Northern Crown for several months in anticipation of a nova erupting soon (sort of soon) in that part of the sky. After the sun set over Lake Michigan, a brewery seemed as good a place as any to await the darkness.

Restaurant illumination did not help with stargazing, but if you look closer...

...six stars of Corona Borealis, the Northern Crown, appear in the original cell phone photograph

A successful constellation sighting (despite no nova) merited a beverage, and to get extra value I asked about takeout beverages available in 16-ounce cans. Our server Tom Z was diligent in tracking down the last remaining chilled four-pack of Bonspiel Noir, a beer name that celebrates curling matches. It also appealed to my friend, whose mother curled into her 80's. Actually, it was for her that we embraced the Bonspiel Noir name.

A pinhole near the edge of the can allows a discreet amount of sunlight to strike black and white photographic paper inside.

The solargraph assembly and mounting had to wait until the ensuing solstice, which was December 2024. One objective was to capture the solar arcs between the solstices in order to image the full range of the sun's path. A side challenge was to mount the can in front of a sundial to get the curving solar lines to intersect the gnomon (the upper part that points north to Polaris) at a right angle. I've succeeded once but want to reproduce the result.

The site overlooks a riverine wetland at the watery intersection of the Galien River and Lake Michigan. The aluminum can sheltering black and white photographic paper is mounted on a stake so that the pinhole is nearly level with the base of the sundial. The pinhole, the aperture of this crude camera, is aimed eastward to center on the gnomon.

The pinhole (the camera's aperture) is nearly level with the sundial and pointed toward the gnomon. March 9, 2025 at 12:26 PM

While a proper sundial is exact, its alignment and human error can introduce misreadings. For example, the gnomon must be aimed toward the north celestial pole. A rough but convenient estimate is to point the gnomon at Polaris at night. To do that, the altitude of the gnomon--that is, the angular height from the horizon up to the gnomon's raised edge--must be equal to the latitude of that site.

If the latitude is 42 degrees North then the gnomon should be elevated 42 degrees. Decorative sundials with gnomons having a fixed angle can only be accurate at gardens along that lone corresponding latitude.

The original scan of the black and white photographic paper is in sepia colors.

For more info on making solargraphs, see https://www.nightwise.org/solargraphs.

Thanks to Tom Z. (shown) and Rick Schmitt (card) of Stormcloud Brewing Company; 2024 August.