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This video is about a multistable perceptual illusion, similar to the hollow face illusion, whereby maps or aerial or satellite photos look upside down/inside out, ie, concave (valley) parts look convex and convex (mountainous) parts look concave. Just flip the images around and things will make a lot more sense! It's just because our eyes gauge depth based on the location of shadows, and the sun always casts shadows on the bottoms of things.

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REFERENCES
Twitter posts:
https://twitter.com/Astro2fish..../status/859799730565
https://twitter.com/BadAstrono....mer/status/859800278

Bad Astronomy Blog post: http://blogs.discovermagazine.....com/badastronomy/201

Multistable perception http://en.m.wikipedia.org/wiki..../Multistable_percept

Top-left Lighting http://en.m.wikipedia.org/wiki/Top-left_lighting

Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute!

Created by Henry Reich