What is afterimage?

When you look at something bright and then look away, it seems to stay on your eyes for a little while, that's called an afterimage.

Imagine you're playing with a flashlight in the dark. You shine it on the wall, and it looks really bright. Then you turn it off and look at the wall again. For a few seconds, it still looks kind of glowing, like it's remembering the light. That’s what happens with an afterimage!

Your eyes have special cells called photoreceptors, which work like little sensors that catch light. When you look at something really bright for a while, those sensors get tired from working so hard. When you look away, they still want to keep doing their job, so they send extra signals to your brain, making it feel like the image is still there.

Next time you're outside on a sunny day, stare at the sun for about 10 seconds (don’t hurt your eyes!), then look at a white wall or piece of paper. You’ll see a bright afterimage that looks like a circle, just like the sun!