Wait, Is This River Floating?

Illustration for article titled Wait, Is This River Floating?

NASA Astronaut Scott Kelly just tweeted this photo, that he took from aboard the International Space Station. You can see the Bighorn River, which stretches through Wyoming and Montana... and, wait, why does it look like it’s floating?

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The explanation for this optical illusion is known as relief inversion, and you may often experience it when looking at satellite photos taken in such a way that the Sun illuminates the landscape from below. This jars with our common (unconscious) expectation derived from everyday experience of the Sun shining on objects from above. Our brain finds it hard to interpret the sight.

So if you rotate the above photo 180 degrees, putting the light source on top, the river is going to look totally normal, flowing through the bottom of its valley. Look:

Illustration for article titled Wait, Is This River Floating?

[Scott Kelly/NASA]

DISCUSSION

RADams5000
RADams5000

For me, the river the first picture didn’t look like it was floating at all. But, the second picture totally looked like it was floating. I read the comments section and now neither one are floating. I spent a good minute starring at them. I feel like the dude from Mallrats.