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Light & Color: Top 10 Questions

April 2013

Thanks to Henry Charlier, associate professor of chemistry, Boise State University; and Kathryn Devine, associate professor of physics, College of Idaho for the answers.

1: Does anything move faster than light?

No. The speed of light is kind of the cosmic speed limit as current physics explain it. So, to the best of our knowledge, nothing can travel faster than the speed of light. (From Ivy at the Idaho Distance Education Academy)

2: What is color?

Color is mostly about the wavelength of light. When astronomers talk about color in a visible image, we are talking about the wavelength of a visible light. Astronomers also use false color images, where we use different wavelengths, and we put those through a computer and assign the shortest as blue and the longest as red. So, we can make a photograph that you may have seen as infrared images in magazines or newspapers. Those are interpretations of assigning colors to wavelengths your eye can't even see. (From Jacob at Dalton Elementary School in Dalton Gardens)

3: How can our eyes see different colors?

Our eyes see different colors because we have special cells in our eyes called cone cells. Cone cells detect color. These cells are set up to see certain wavelengths of light. When certain wavelengths hit those cells, they trigger a message that is sent to our brain. Then our brain comes up with what we think that color is. This is what we see. (From McKenna at the Idaho Distance Education Academy)

4: How many colors are there?

There are an infinite number of colors. It depends on how sensitive your eyes are to see the difference. A light wave causes a color to be a color. Light travels as a wave and the distance, peak to peak, is the wavelength of the light. A light wave can have any numbers of wavelengths, but that one is what determines the color of the light. There is no limit. So, there are an infinite number of color possibilities. (From Miya at Cynthia Mann Elementary School in Boise)

5: Is light a wave or a particle?

This is a tricky question because it's both. Light does behave like a wave. However, a digital camera experiences light like a particle because the photon hits the screen and you capture it like you would a particle. So, light has wave- and particle-like behavior. (From Logan at Idaho Distance Education Academy)

6: Why is it when you look at the sun you hurt your eyes?

The sun has lots of types of light that shine down on the earth. Some of them fall in the category of visible light, but there is some light that you can't see. One of them would be ultraviolet light. Ultraviolet light can cause a lot of damage when it shines on something like tissue. When the eyes absorb this kind of light, it can cause damage to your eyes. So, you could really hurt yourself looking at the sun. (From Jazmin at Dalton Elementary School in Dalton Gardens)

7: Are there types of colors we cannot see?

Yes. There is light that our eyes cannot pick up on or differentiate. It's kind of invisible to us. Our eyes have the ability only to see a tiny bit of what could be possible to see. We have built telescopes that can see in the longer and shorter wavelengths that we cannot see with our eyes (infrared or ultraviolet light). These telescopes can make pictures in a way that's visible to your eye, so we can see what's going on. (From Sarah at Kamiah Elementary School in Kamiah)

8: Are there different kinds of light?

Light is not just the type of light we see with our eyes. Only visible light is what you can see. However, there are other types of light. X-rays, ultraviolet and infrared rays are all types of light. The shortest waves of light are gamma rays and radio waves are the longest wavelength of light. (From Ella at the Idaho Distance Education Academy)

9: Why do computers make colors out of the colors red, blue and green?

There are many different ways that we can describe color. Depending on the application, what we are using it for, we have different ways of expressing a specific type of color called primary colors. When a computer screen, or even an overhead light, shines different colors, they add in such a way that if you were to mix red, green and blue, you would actually get white light. If you were to mix red and green together and shine them down on each other, you would actually see yellow. (From Ethan at Cynthia Mann Elementary School in Boise)

10: Why does the sea look blue from above, but clear if you scuba dive?

If you are out on the beach on a beautiful day, the water looks blue because the water is reflecting the light from the sky. The sky looks blue because there is a lot of stuff in our atmosphere like dust and gas. As white light from our sun comes into the atmosphere, it gets scattered. Blue light scatters more than the longer wavelengths of red, and that turns the sky blue. The water then reflects the sky so the ocean looks blue. When you scuba dive, it looks clear near the surface, but if you go deep enough, the blue light goes away and you see things mostly in red. The blue light gets scattered away and you are only left with red, the longest wavelengths of light. (From Justice at the Idaho Distance Education Academy)


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