For most of us, the first time we would have learned about indigo would have been in school, when we were taught color theory and the acronym for the colors of the rainbow: ROYGBIV. Of course ...

The colors of the rainbow always show up in the same order: red, orange, yellow, green, blue, indigo and violet. It's organized by wavelength. Red, with the longest wavelength, is on the outside ...

Of his rainbow experiment Newton wrote that he had projected ... In his diagrams, which showed how colors corresponded to notes, Newton introduced two colors—orange and indigo—corresponding to half ...