Archaeo-optics in Orkney Day 8: Success! Another sunset inside Wideford Hill cairn

Overcast skies ruled out any chance of dawn observations at Cuween Hill this morning, but the clouds did part to allow direct sunlight into the chamber of the Wideford Hill cairn at dusk. This added some new material to our visit at sunset a few days previously.

Looking down the passageway from inside the chamber of Wideford Hill. An aperture screen is in place at the entrance, showing what projected sunlight looks like when viewed in the opposite direction to the image itself (Photo: Aaron Watson)
 
Without any kind of aperture, light from the setting sun floods down the passage. The area it illuminates frames one of the side cell entrances within the chamber (Photo: Aaron Watson)
 
Direct sunlight entering a side cell within Wideford Hill (Photo: Aaron Watson)