Archaeo-optics in Orkney Day 1: Sunset at Wideford Hill cairn

Amazing - the clouds in the western sky began to clear. In fading light we walked down the path to the passage cairn on the flanks of Wideford Hill. In 2015, I had projected images of human figures and the landscape within this cairn during the daytime. On this visit, I hoped we might be able to record the solar disc projected into the chamber.

After setting up an aperture screen at the outside entrance to the passageway we waited in the chamber. In daylight, the projected image frames the entrance to one of the smaller cells that were constructed around the main chamber. At sunset, the image of the sun appeared deep within this cell.

The dazzling orb of the solar disc, optically projected into a side cell within Wideford Hill cairn (Photo: Aaron Watson)

We then removed the aperture in the passage, allowing sunlight to flood through, emphasising the enormous contrast between optical projection and an open passageway.

Direct light entering Wideford Hill cairn, illuminating the wall of the main chamber and passing through into the side cell beyond (Photo: Aaron Watson)