Abu ‘Ali al-Hasan ibn (965-c. 1039) was a brilliant scientist in many areas, including engineering, physics, philosophy, mathematics, astronomy, anatomy, medicine, philosophy, psychology, and more. He has been called the “Father of Modern Optics” and the “Founder of Experimental Physics,” attesting to his many accomplishments. His seven-volume Book of Optics (1011–1021) explained principles with applications ranging from ophthalmology to astronomy to meteorology. As it pertains to meteorology, his work is important for explaining such concepts as reflection, refraction, transparency, translucence, radiancy, and optical illusions (e.g., mirages). He made contributions to the study of rainbows and atmospheric density.