The eye’s retina receives and reacts to incoming light and sends signals to the brain, allowing you to see. One part of the retina, however, doesn't give you visual information—this is your eye’s “blind spot.”
The earth’s atmosphere may seem thick when compared to something like your ...
The earth’s atmosphere may seem thick when compared to something like your height—but it’s surprisingly thin when compared to the earth’s radius. Here, you can find out exactly how thin, using strips of plastic to model the correctly scaled thickness of the atmosphere on a globe.