The crescent was a moon symbol for thousands of years before Islam
Akkadian cylinder seals from as early as 2300 BC already show a crescent standing for the moon god Nanna. The same curved shape later crowned Greek goddesses, marked silver for alchemists and sat beneath the feet of the Virgin Mary, long before Ottoman mosque finials tied it to Islam.
The word comes from the Latin crescere, to grow, and strictly means the waxing moon. Seen from the northern hemisphere, a waxing moon's horns point left and a waning one's point right. Heraldry keeps the distinction precise: increscent for horns to the left, decrescent for horns to the right, and plain crescent when they point up.
Ancient peoples used it widely. Egyptian writing had a crescent-shaped sign for the moon, the Phoenicians carried the symbol as far as Carthage in the 8th century BC, and South Arabian coins bore a star and crescent before Islam arose. Pairing the two stood for the moon and Ishtar, the planet Venus. Selene wore a crescent on her head, often called her horns, and in Hellenistic art it became the badge of Artemis-Diana, which linked it with virginity.
Christian art picked it up through the Woman of the Apocalypse in Revelation, standing on the moon; the Virgin of Guadalupe is the best-known image of Mary in that role. On some Russian Orthodox domes a cross rises above a crescent. That is sometimes misread as Christianity triumphing over Islam, but such domes were built in 12th-century Russia before Islam reached Kievan Rus'.
Geometrically, a crescent is a lune: a disc with part of another disc cut out, leaving a shape bounded by two arcs that does not include the original centre. The actual crescent moon differs slightly, outlined by half an ellipse and half a circle. The United States military introduced a crescent badge for Muslim chaplains in 1993.
Source: Crescent
