What is the color of light?

About 10 years ago I wrote a 20th anniversary poem for my wife, Jenny. She placed it in a glass frame which sits on a sideboard in our dining room.  

 

On one particular fall afternoon last year, the sun turned that frame into a prism and painted the sideboard, nearby decor and even our hardwood floors with the visible light spectrum. The brilliance was indescribable.

 

This got me thinking: What color is light?  

 

For something so central to our daily lives, it’s rather difficult to say.  

 

I asked Jenny if she knew the colors of the visible spectrum.  

 

“You mean ROY G BIV?” she asked.  

 

Her retention of grammatical rules and other tidbits from her middle school years still amazes me. I had forgotten that acronym long ago. But most of us learned in science class that the visible light spectrum is red, orange, yellow, green, blue, indigo and violet, or “ROY G BIV.”  

 

We also learned that each of these colors has specific wavelengths ranging from about 380 nanometers (nm) for violet up to around 750 nm for red. With some variations between people, that’s what most of us can see.  

 

A prism bends (refracts) the various wavelengths of light differently, dispersing it into its individual colors. A rainbow is another example of a similar phenomenon.

 

But as pretty as rainbows and the visible spectrum displayed across our sideboard and floor may be, they involve only a tiny part of the electromagnetic spectrum or the full range of light.  

 

We humans can get a nasty sunburn from ultraviolet light, just beneath violet in wavelength, but we can’t see it. X-rays have even shorter wavelengths than ultraviolet. We are all familiar with the medical and dental benefits x-rays afford us.

 

But back to the visible spectrum. Even that is a bit open-ended.  

 

Did you know that birds, bees, dogs, deer and all kinds of animals don’t see the world as we do?  Birds and bees can see at least some ultraviolet light. Cynthia Berger wrote an article for the National Wildlife Federation titled “True Colors: How Birds See the World.” In it she explains that, while we humans may perceive both sexes of some bird species as identical, the birds can see beyond our limits.  

 

The male blue tit, a European relative of the chickadee, looks like a female blue tit except for the shiny patch of feathers on his head that strongly reflects UV light. The birds can see that. 

 

Deer hunters in most states are required to wear bright orange safety vests so that they can see each other. Deer are not able to discriminate between orange and most natural forest colors.

 

The next time you ponder the colors and beauty of a rainbow, you will know just what you are seeing. But don’t expect your dog to get excited. His world is mostly shades of gray, brown, yellow and blue. His sense of smell, however, is fantastic and even a blind dog knows about that treat you’re hiding in your pocket. Come on, give it up!