Alhazen’s book Maqala fi al-Hala wa Qaws Quzah
(“On the Rainbow and Halo”) proposed an incorrect
theory how a rainbow forms. The correct theory for the primary
rainbow was proposed by Theodoric of Freiberg in 1304, and
René Descartes explained the secondary rainbow in 1637.
Even so, Descartes did not understand the nature of color,
thinking that each color was a modification of white light. In
1672, Isaac Newton explained that white light is composed of a
spectrum of coloured light.
See also in The book of science:
Readings on wikipedia: