Newton’s Revisions

Take a look at the rainbow above. Notice anything about the colors?

There’s an extra blue!

This rainbow follows the ROYGBIV (Red Orange Yellow Green Blue Indigo Violet) system. You’ve probably seen it, but if someone asked you to paint a rainbow, you probably wouldn’t paint it this way. You’d probably leave out the Indigo. The new standard rainbow of colors is ROYGBV. No indigo. This, I’m certain, is the fault of Gay Pride, Pink Floyd, and Sparkle Pony.

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There have been many attempts to simplify and organize the color spectrum, but the most well known arrangement was Sir Isaac Newton’s color wheel, as he observed white light divided by a prism.

Newton’s original idea of the simplified color wheel (sometime around 1665) was just 5 colors: Red, Yellow, Green, Blue, Purple. Then, 10 years later, in his revision Lectiones Opticae of 1675 he added two new colors: Orange and Indigo. With the two new additions, we were given ROYGBIV. In his words: “The originall or primary colours are Red, yellow, Green, Blew, & a violet purple; together with Orang, Indico, & an indefinite varietie of intermediate gradations.” Of these widely accepted seven colors, three are primary (red, yellow and blue); three are secondary (green, orange and violet) and only one is tertiary (hello indigo). 

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So why did Newton add the tertiary color Indigo? Newton might have included indigo as a 7th color because he wanted to match the colors in the rainbow to the notes in a Dorian scale of music.

In Newton’s “octave” of colors, orange and indigo are placed at the half steps, between E and F and between B and C.

Newton’s revised color wheel drawing shows the new orange and indigo. All colors were represented in exact proportion to their prominence when divided from the prism.

Red, yellow, and blue were the primary colors for hundreds of years, only recently replaced with cyan, magenta, and yellow. Essentially, we just took the color wheel and turned it a few degrees so our printer inks would work better.

Newton’s blue (originally called ceruleus) is different from our blue today, and could now more accurately be called… well… cyan. So, the blue drifted, and then we fixed it.

Feeling blue? You can get all the blue you want – Indigo is this Saturday!

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Resources:

https://en.wikipedia.org/wiki/Indigo_dye

https://en.wikipedia.org/wiki/Indigo

https://royalsocietypublishing.org/doi/10.1098/rsta.2014.0213

Sir Isaac Newton’s Influence on the Color Wheel

https://nationalpost.com/news/why-the-colour-indigo-is-disappearing-from-sir-isaac-newtons-occult-rainbow