An illustration from al-Biruni's astronomical works, explains the different phases of the Moon, with respect to the position of the Sun, from manuscript of the Kitab al-Tafhim by Al-Biruni (973-1048). The illustration demonstrates: The Moon's orbit shown by the elliptical path with red lines; Different phases of the Moon represented by the circles divided into black and illuminated (red/white) portions; The Sun's position (indicated by the Arabic text on the right: "al-shams" meaning "the sun"); Geometric lines showing the relationship between the Sun's light and the Moon's appearance from Earth; Arabic annotations explaining the astronomical concepts. https://en.wikipedia.org/wiki/Al-Biruni#/media/File:Lunar_phases_al-Biruni.jpg