What is color? What a great question!
All around us, there is a type of energy called electromagnetic radiation. Microwaves cook our food using this type of energy. X-ray machines at the dentist office use this type of energy.
One way to picture electromagnetic radiation is that it moves from one place to another in waves. Imagine if you tied a rope to a tree and shook it up and down, you’d see waves moving—one end to the other—and hitting the tree. Can you picture it? If you shake the rope slowly, the waves will be far apart. As you speed up, these rope-waves will get closer together. We call this the “frequency” of a wave. High frequency waves are close together, and low frequency waves are far apart.
And now—finally!—we’re ready to talk about color. If the frequency of the electromagnetic radiation is just right, we can see it! Red is a low-frequency light wave. Picture somebody shaking a rope up and down slowly. Greens are in the middle. Blues are the highest frequency. So there you have it – color is light energy at just the right frequency.
As we finish up, here are some interesting facts about color. Did you know that about 1 out of every 20 boys can’t see a difference between red and green? That’s why traffic lights always have red on top and green below, so that everyone knows when to start and stop! Color gives us lots of useful clues about our world. Seeing a yellow banana lets you know it’s ready to eat. Some animals, like bees, can even see colors that we don’t. We still have a lot to learn about color, but one thing is for sure—color makes the world a very interesting place.
Let’s start with another question. What is a rainbow? Is it an object? Can you touch it? When I was a kid I would always try to run under the rainbow to the other side. Unfortunately I never succeeded, it kept escaping me. It’s really a fascinating thing. It’s right there, we can clearly see it, but it doesn’t really exist! I learned later in a physics class that the rainbow is just light – the same white light that comes from the sun, but when it passes through tiny drops of rain it turns into layers of beautiful colors!
Let’s get back to color now. A rainbow has all the colors that you can find anywhere, but really a rainbow is just light. So color and light are pretty much the same thing – one doesn’t exist without the other. Walk into a very dark room and try to see any colors. Everything becomes boring and colorless without light. But how do things start having different colors when there is light? As we found out from the rainbow, white light really contains many different colors, right? When white light shines on something, it’s actually light of all the colors. When an object receives this light, it can keep all the colors or only send some of them back to our eyes. Grass, for example, chooses to keep all the colors of white light except for green. This green light gets to our eyes and we see that grass is green! If an object keeps all the colors and doesn’t send anything back, it will appear black, same as the dark room. On the other hand, if the object sends all the colors back, it will appear white because white is really made of all the colors.
Did you know that dogs don’t see all the colors we do? Dogs only see yellow, blue and gray. Humans see quite a few more: red, yellow, green, and blue are just a few of the colors that we see.
Color itself isn’t a thing we can touch like a pencil or a book; color is how our eyes interpret reflection of light off of certain objects. That’s why we don’t see colors in the dark; there’s no light to reflect.
The key is in the light itself. It helps to think of light like waves in the ocean. Sometimes waves are shorter and more frequent, and sometimes they’re taller and more spread out. Just like different lengths of waves make different patterns in the sand, different wavelengths of light make different patterns (colors) in our eyes. The different colors we see are actually just different wavelengths of light. For example, blue is a shorter wavelength than red, so our eyes see it differently. But, unlike waves in the ocean, wavelengths of light are incredibly small.
So why can humans see more colors than dogs? It’s because of cones in our eyes. Humans have three “cones” at the backs of our eyes that are color-specific. No, they don’t actually look like ice cream cones, but we can think of them like that. By color-specific, I mean “wavelength”-specific. There is a cone for shorter waves of light (blues), a cone for long waves of light (reds), and a cone for in-between lengths (greens). All the other colors, such as orange and yellow, are seen with our cones working together. Dogs only have two cones in their eyes instead of three, so they see fewer colors.
Now you know why people look at you funny when your dog picks out your clothes!