Science with Grammarsaurus - How do our eyes see?

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How do our eyes see?

Your eyes allow you to see the world around you. Their main job is to spot patterns of light. Eventually, these patterns are turned into detailed images, but how does this happen?

To start with, light rays bounce off an object that you are looking at. The light reflects off that object into your eye, entering through the cornea. Your cornea is transparent and it helps your eye to focus the light, making it clear and sharp.

Next, the light rays pass through an opening called the pupil. Your pupil is the dark, round circle in the coloured part of your eye. The coloured part is called the iris. It is the iris’ job to control how wide the pupil is and how much light can pass into your eye.

When it is bright, the muscles in the iris narrow the pupil. This reduces the amount of light that can enter the eye. When it is darker, the muscles in the iris widen the pupil. This increases the amount of light which can enter the eye.

As the light travels through the pupil, it passes through a lens which sits just behind it. The lens focuses the light on the retina and helps you to see more clearly. The retina can be found on the back of the eye.

The front of the eye is curved. This means it bends the light as it enters. This causes the image that appears on the retina to be upside down.

There are about 130 million tiny cells in the retina. They are all sensitive to light. When they detect light, they turn them into electrical signals.

These signals then travel through the optic nerve to the brain. It is the job of the brain to sort the information it has been sent to create a detailed image. It is also the brain that turns what you see the right way up!

Each eye sees a slightly different image when you look at something. Your brain takes each view and combines them, creating one picture. The brain also adds more detail to the image including colour, depth, movement and complex shapes.

Your brain also connects your sense of sight to what you already know so that when you see a cat, you recognise it as a cat rather than a goat!