In the celebrations of the
fifty-year forty-year anniversary of the moon landing, we’ve probably all seen this iconic photo of Buzz Aldrin’s footprint on the lunar surface:
Looking at it again yesterday, I realised that there was something that disturbed me about it. The footprint looks wrong somehow. Our world-knowledge tells us that footprints press into the surface they are made on, yet this footprint looks like it rises out. What gives?
The effect is due to a well known visual phenomenon whereby our brains use shading to infer the percepion of shape (in the book, Hack #22). We are wired to assume that light comes from above, so things with shading underneath, like the ridges of the footprint, are seen as sticking out towards us. Things with shading on the top are seen as sticking in, away from us.
You can make the moon-footprint look ‘right’ by turning the photograph the other way up. This is the opposite to the way it is normally shown, but gells with our natural inclination to assume light comes from the top of the photo:
Perhaps the unnatural look of this photo is one source of moonlanding-denial conspiracy theories?