Introduction to Solar Observing	Course Overview	Course Syllabus	Course Schedule
		Index of Course Sessions

Newton's "Celebrated Phenomenon of Colours"

In 1666, Isaac Newton passed a narrow beam of sunlight through a glass prism in order to prove that the seemingly white light from the Sun actually consisted of all the colors of the rainbow. As expected, the prism spread the light into a blur of colors ranging from violet and blue at one end, through green and yellow, to orange and red at the other end, as illustrated in Figure 1. Newton used the Latin word spectrum (pl. spectra), meaning "apparition" or "specter", to describe this rainbow of colors.
	Figure 1 When white light passes through a prism a spectrum is produced.