Solargraphs from the Queen’s House roof
At the top of the Tulip Stairs, we stepped out onto the roof of the Queen’s House. Two weeks earlier, with permission from Royal Museums Greenwich, Frederik Botha and I had set up seven tiny pinhole cameras to photograph the Sun’s path over Greenwich Park. After a spell of wind and rain, we were keen to see how they had fared. The first thing I saw was a crow flying away from the stand. This did not seem especially promising.
As we got closer, we could see that the stand was still in place. One puck holder had moved, but everything else looked as we had left it. Greg Brown had thoughtfully brought disinfectant wipes. As far as we could tell, the crows had given him no reason to use them.
How a solargraph works
A solargraph is a long-exposure photograph that records the Sun’s path across the sky. A tiny pinhole projects an image onto light-sensitive photographic paper inside the camera. The Sun draws a bright line as it crosses the sky, and passing clouds can leave gaps in that line. Leave the camera in place for several days and the individual tracks begin to build up.
Trials at the Royal Observatory
I’d been experimenting with solargraphs for about two years, using both preloaded cans and reusable cameras about the size of an ice hockey puck. On 18 April 2026, I attached one of these pucks to a post during a Flamsteed solar viewing session at the Royal Observatory. Five hours was enough to record part of the Sun’s path.
At later sessions I tried different positions around the Observatory, including the balcony on 30 May. On 25 July we tried Frederik’s prototype stand with two pucks, giving us two views from the same spot.
18 April 2026. The first trial puck attached to a post at the Royal Observatory. 18 April 2026. The Sun left a short bright trail during the five-hour exposure. 30 May 2026. A solargraph taken from the Royal Observatory balcony. 25 July 2026. Frederik’s prototype stand carrying two pucks at the Royal Observatory. 25 July 2026. A solargraph from the black puck on the prototype stand. 25 July 2026. Another solargraph from the white puck on the prototype stand.
Trial photographs and solargraphs by Yvonne Jacobs.
Getting permission for the roof
At a solar viewing session we could only leave the pucks out for a few hours. For a longer exposure, Flamsteed vice-chair Simon Hurst spoke to the Observatory astronomers. With the Observatory due to close for refurbishment, the Queen’s House roof was suggested.
Royal Museums Greenwich needed to approve a suitable stand before we could install anything. Frederik designed and 3D-printed prototypes, which we tried at solar viewing sessions. The museum’s facilities team reviewed the designs, and the final stand Frederik made was approved for the roof.
Two weeks on the Queen’s House roof
We installed the stand in mid-October with Ed Bloomer from the Royal Observatory and Gary and Darren from the museum’s facilities team. I mounted three pucks level, each pointing in a slightly different direction. Frederik fitted a commercial puck and three he had 3D-printed himself, each with a different pinhole size. We also tried different photographic papers.
The installed stand, looking across Greenwich Park towards the Royal Observatory. The view from the Royal Observatory. The arrow marks the stand on the Queen’s House roof.
Roof photographs by Yvonne Jacobs.
What the cameras recorded
The photographs show bands of bright tracks above the Greenwich Park skyline. The three pucks I aimed in different directions give slightly different views, including one towards Flamsteed House. The puck that shifted produced the most unexpected image. The camera recorded the Sun’s path at one angle before the shift and another afterwards, so the tracks cross.
The trial gave us our first solargraphs from the roof and showed how the stand coped with two weeks outdoors. With seven images to compare, we have a starting point for trying longer exposures.
Solargraphs from the first roof trial
Three views by Yvonne Jacobs
Puck 1, pointed slightly to the right. Puck 2, pointed towards Flamsteed House. Puck 3, pointed slightly to the left.
Four views by Frederik Botha
The commercial puck, with a band of closely spaced Sun tracks. The homemade puck that shifted, leaving two sets of Sun tracks crossing. A homemade puck with several Sun tracks visible above the treeline. Another homemade puck, with two prominent tracks over the horizon.
Thanks to Royal Museums Greenwich for making the trial possible, and to Ed Bloomer, Gary and Darren for helping us get the project onto the roof.
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