Visible light spectrum experiment. Historical artwork of the experiment that showed how a prism (upper left) can be used to split a beam of white light into its component colours. The spectrum of visible colours (upper right) is also seen in nature as the colours of the rainbow. From top to bottom the colours are: violet, indigo, blue, green, yellow, orange and red. The English physicist and mathematician Isaac Newton (1642-1727) was the first to explain this phenomenon, carrying out this experiment in the 1660s. He identified the seven colours named here, but the results were not known until he published Opticks (1704).