How do our eyes “get used to the dark”?
In: Biology
Nighttime is WAY darker than daytime – ten million times darker. Seeing in the day is like measuring the speed of a whole river of light, while seeing at night is like counting drips of it. These are such different problems that our eyes use different cells to solve them.
During the day you measure that river of light with ‘cone’ cells. There are three types with different sensitivities that let you see different colors. During the night, you use ‘rod’ cells that have a delicate chemical mousetrap to catch the little drips of light that come in. Switching to the night vision system takes a while (20-30 minutes or so) because all of those little mousetraps (a chemical called rhodopsin) have been destroyed by the river of light you were just in.
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