Example of a Brocken spectre
Source: Daily Record

The Brocken spectre is an optical illusion in which the apparently greatly magnified shadow of an observer, when projected onto a surrounding mist by a back light such as the setting Sun, interferes with that observer’s depth perception. The shadow is perceived to be further away than it is in reality when seen against a background of features known to be far away, and hence much larger than it actually is.[1]

The phenomenon takes its name from the highest peak in the Harz Mountains of north central Germany, the Brocken, where it was first reported.[2] The term was coined in 1780 by Johann Silberschlag, a German pastor and natural scientist.[3]

Other manifestations of the illusion include the Grey Man of Ben Macdui – Am Fear Liath Mòr in Scottish Gaelic – a creature once believed to haunt the summit and passes of Ben Macdui, the second highest peak in the British Isles after Ben Nevis.[4][a]Ben Macdui is in the Scottish Cairngorms.




Dunlop, Storm. “Brocken Spectre.” Dictionary of the Weather, Online, Oxford University Press, 2008, https://www.oxfordreference.com/view/10.1093/acref/9780199541447.001.0001/acref-9780199541447-e-2119.
Knowles, Elizabeth. “Brocken.” The Oxford Dictionary of Phrase and Fable, Online, Oxford University Press, 2006, https://www.oxfordreference.com/view/10.1093/acref/9780198609810.001.0001/acref-9780198609810-e-1100.
Townsend, Chris. Scotland. Cicerone Press, 2010.