There was a radio contest giving this question on my way home, but I never heard the answer… A lot of people were saying red orange green yellow blue indigo violet… the ol’ ROYGBIV… They said that was wrong. I remembered something about the indigo being discarded. I call back with that, no, not right answer. What is the answer?
I think the yellow should come before green in your list.
According to my science teacher at school, Indigo was included by Newton as ‘God did things in sevens’, hence 7 colours of the rainbow. That knida makes sense as if you ask anyone what colour indigo is, they say ‘a bluey - violety colour’.
I take that back. Marshal Brain at howstuffworks.com doesn’t seem to make that distinction he’s usually right.
This guys says 7 colors too. I’ll quit now.
Depending on the color model you use brown can be considered “dark orange.” Open an application with a HSL color picker like windows desktop properties or photoshop. Pick the hue for orange then play with the saturation and lightness sliders until you get brown.
Gray is easy, gray is dark white or bright black. I can put up a black backdrop cloth and with the correct light and exposure it will look white.
Silver doesn’t have a clear definition but I think is best described as the color of a mirror.
Clear? Someone will be along shortly to adminster dope slap 
Depending on the color model you use brown can be considered “dark orange.” Open an application with a HSL color picker like windows desktop properties or photoshop. Pick the hue for orange then play with the saturation and lightness sliders until you get brown.
Gray is easy, gray is dark white or bright black. I can put up a black backdrop cloth and with the correct light and exposure it will look white.
Silver doesn’t have a clear definition but I think is best described as the color of a mirror.
Clear? Someone will be along shortly to adminster dope slap
Red
Orange
Yellow
Green
Blue
Violet
If you include Indigo, then you have to include orangey-red, gold, chartreuse, and aqua.
Then again, we can discuss the fact that the three primary colors are Red Yellow and Blue, while TVs and Computers use Red Blue and Green… which I don’t understand how we get orange on computers then, or yellow for that matter
The three primary colors of light are red blue and green. The three primary pigmentary (is that a word?) colors are, IIRC, yellow, magenta, and cyan.
mnemonic: Roy G. Biv
For Red, Orange, Yellow, Green, Blue, Indigo, Violet
Yellow is a mixture of equal parts red and green. Don’t believe me? Open up your paint program, zoom in so you can see individual pixels, and color them in a red/green checkerboard pattern. Copy and paste that checkerboard many times over, so it covers a large area. Now unzoom, step back a few feet from the monitor, and see what color you see. Then get close again and squint at it, to convince yourself that the individual pixels are still red and green.
Orange is about halfway in between red and yellow, so you can get it on an RGB monitor by about three parts red to one part green.
I’m going with Bruce_Daddy’s first guess - I thinkt here are infinite (or near infinite - however small we define a wavelength/frequency) colors seen in a rainbow.
Making all the colors possible is a bit more complex than just the colors of the spectrum. The spectrum has one dimension, wavelength. Remember there’s no brown in a rainbow. A full color display has at least three dimensions. For additive colors like a monitor it can be expressed as one dimension each for red, blue and green or by hue, saturation and lightness. For printing it’s three or four dimensions with cyan, magenta, yellow and black.
Here’s how to make it simple:
Light has FREQUENCY, not color.
“Color” is something perceived by humans.
So, a rainbow has an infinite number of frequencies, since for any two frequencies there is always another one in between.
The question could be clearer: how many “distinguishable colors” are in a rainbow? First you need a standard human! I’ve heard the number quoted as being around 50 to 70 colors. More than that, and no human can tell the adjacent colors apart.
Also, it depends on the rainbow as well as upon the human eye. Smaller raindrops give scattering through interference, and cause the colors to blur together, so the center of the rainbow becomes pastel-ish.
Finally, the sun is too damn wide, and it causes some blurring of the rainbow colors. If the sun was a point source (like a welder’s arc), then rainbows would probably have more distinguishable colors… and also they’d be full of black lines. Sunlight frequency distribution isn’t smooth, it’s full of slots caused by atomic absorbtion. If the sun was a pointsource, then rainbows would look like this:
ROYGBIV is a convention based on the words we have for spectral hues and the amount of detail we want to go into to describe those hues. You could also say blue,green,yellow,red or red,orangyred,reddyorange,orange …etc
As Padaye said, the non spectral colours are created by altering the saturation and brightness of spectral hues. eg orange–>brown
Woah dude dejavu - recent thread
Regarding the OP, what was the actual question asked by the radio station?
Richard Of York Gave Battle In Vain
Or, as suggested by my school Physics teacher:
Roll Over You Great Big Innocent Virgin.
he asked everyone to “list the colors in the rainbow.”