The Pupil of Your Eye

eyes · light · how vision works · super cool

What is it?. Your pupil is a hole right in the middle of the colored part of your eye called the iris. It looks black because light that goes through it gets swallowed up by the tissues inside your eye instead of bouncing back out.

Controls the light. Your iris automatically makes your pupil bigger or smaller depending on how bright it is around you. In a dark room, your pupil opens wide like a door to catch more light, and in bright sunshine, it shrinks to a tiny dot to protect your eye.

Helps you see. The pupil is the gateway that lets light reach the retina at the back of your eye, which is the special layer that sends pictures to your brain so you can see the world.

Always changing. Your pupils are constantly adjusting throughout the day, even when you're not thinking about it. When you're excited or focused on something, your pupils might even get a little bigger naturally.

Ancient name. A scholar named Gerard of Cremona came up with the word 'pupil' hundreds of years ago, and people still use that same name today.