Let's learn about science: Light and vision

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Everybody knows that we need light to see, but did you ever wonder if other people see things the same way you do? What about animals? Let’s shine some light on the subject.

Our eyes have two special kinds of cells that sense light — rods and cones. Rods help us see shapes and motion. Cones let us see color. Our cones can see three colors: red, green and blue. By combining these three colors we can see about 10 million hues. Sometimes a person is born who has problems seeing red or green light. This happens to about 1 in 12 men and 1 in 200 women. These people have trouble telling the difference between red, orange and green objects. Very rarely a woman is born with a fourth kind of cone. Some of these women might be able to see more than 100 million colors.

Some animals have better color vision than humans. Birds, butterflies and bees have cones that can see ultraviolet light. This light is invisible to us, so it is hard to image how these animals see the world. Bees and butterflies use their ultraviolet vision to find flowers. Birds that look plain to us might look quite different to their feathered friends. Some birds even use their ultraviolet vision to track down prey.

Did you know that light is a kind of radiation made by the sun? So are microwaves, X-rays and radio waves. Our atmosphere protects us from most of the dangerous kinds of radiation. We can’t see these other kinds of radiation, but we can make telescopes that can. We can also make cameras that see infrared radiation. We can’t see infrared, but we can feel it as heat.

It’s easy to think that we see the world as it really is. The truth is there is an unseen universe right in front of our eyes.


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