Odd truths about the human body
Strange things happening inside you right now.
Do human beings glow in the dark?
Yes, faintly. Human bodies emit a small amount of visible light as a by-product of metabolism. Researchers imaged it with ultra-sensitive cameras in 2009. It is roughly a thousand times weaker than the human eye can detect, so nobody has ever seen it.
Why can't I see the blind spot in my own eye?
Because your brain fills it in. Each eye has a patch of retina with no photoreceptors, where the optic nerve exits. You never notice the gap because your visual system invents plausible content to cover it, using whatever surrounds the hole.