A crescent shape is a symbol or emblem used to represent the lunar phase in the first quarter (the “sickle moon”), or by extension a symbol representing the Moon itself.
Crescent is used as the astrological symbol for the Moon, and hence as the alchemical symbol for silver.
It was also the emblem of Diana/Artemis and hence represented virginity. In Roman Catholic Marian veneration, it is associated with the Virgin Mary.
The crescent shape is a type of lune, the latter consisting of a circular disk with a portion of another disk removed from it so that what remains is a shape enclosed by two circular arcs which intersect at two points. In a crescent, the enclosed shape does not include the center of the original disk.
The tapered regions towards the points of intersection of the two arcs are known as the “horns” of the crescent. The classical crescent shape has its horns pointing upward (and is often worn as horns when worn as a crown or diadem, e.g. in depictions of the lunar goddess, or in the headdress of Persian kings, etc.)
The word crescent is derived etymologically from the present participle of the Latin verb crescere “to grow“, technically denoting the waxing moon.
As seen from the northern hemisphere, the waxing Moon tends to appear with its horns pointing towards the left, and conversely the waning Moon with its horns pointing towards the right; the English word crescent may, however, refer to the shape regardless of its orientation, except for the technical language of blazoning used in heraldry, where the word “increscent” refers to a crescent shape with its horns to the left, and “decrescent” refers to one with its horns to the right, while the word “crescent” on its own denotes a crescent shape with horns pointing upward.
The shape of the lit side of a spherical body (most notably the Moon) that appears to be less than half illuminated by the Sun as seen by the viewer appears in a different shape from what is generally termed a crescent in planar geometry: Assuming the terminator lies on a great circle, the crescent Moon will actually appear as the figure bounded by a half-ellipse and a half-circle, with the major axis of the ellipse coincides with a diameter of the semicircle.
It is primarily used to represent the Moon, not necessarily in a particular lunar phase. When used to represent a waxing or waning lunar phase, “crescent” or “increscent” refers to the waxing first quarter, while the symbol representing the waning final quarter is called “decrescent“.
The crescent symbol was long used as a symbol of the Moon in astrology, and by extension of Silver (as the corresponding metal) in alchemy. The astrological use of the symbol is attested in early Greek papyri containing horoscopes. In the 2nd-century Bianchini’s planisphere, the personification of the Moon is shown with a crescent attached to her headdress.
Its ancient association with Ishtar/Astarte and Diana is preserved in the Moon (as symbolized by a crescent) representing the female principle (as juxtaposed with the Sun representing the male principle), and (Artemis-Diana being a virgin goddess) especially virginity and female chastity.
In Roman Catholic tradition, the crescent entered Marian iconography, by the association of Mary with the Woman of the Apocalypse (described with “the moon under her feet and on her head a crown of twelve stars” in Revelation) The most well-known representation of Mary as the Woman of the Apocalypse is the Virgin of Guadalupe.
The crescent shape is used to represent the Moon, and the Moon deity Nanna/Sin from an early time, visible in Akkadian cylinder seals as early as 2300 BC.
The crescent was well used in the iconography of the ancient Near East and was used transplanted by the Phoenicians in the 8th century BC as far as Carthage in modern Tunisia. The crescent and star also appear on pre-Islamic coins of South Arabia.
The combination of star and crescent also arises in the ancient Near East, representing the Moon and Ishtar (the planet Venus), often combined into a triad with the solar disk. It was inherited both in Sassanian and Hellenistic iconography.
In the iconography of the Hellenistic period, it became the symbol of Artemis-Diana, the virgin hunter goddess associated with the Moon. Numerous depictions show Artemis-Diana wearing the crescent Moon as part of her headdress.
The related symbol of the star and crescent was the emblem of the Mithradates dynasty in the Kingdom of Pontus and was also used as the emblem of Byzantium.
The crescent remained in use as an emblem in Sassanid Persia, used as a Zoroastrian regal or astrological symbol. In the Crusades, it came to be associated with the Orient (the Byzantine Empire, the Levant, and Outremer in general) and was widely used (often alongside a star) in Crusader seals and coins.
It was used as a heraldic charge by the later 13th century. Anna Notaras, daughter of the last Megas doux of the Byzantine Empire Loukas Notaras, after the fall of Constantinople and her emigration to Italy, made a seal with her coat of arms which included “two lions holding above the crescent a cross or a sword“.
From its use in Sassanid Persia, it is also found its way into Islamic iconography after the Muslim conquest of Persia. Umar is said to have hung two crescent-shaped ornaments captured from the Sassanid capital Ctesiphon in the Kaaba.
The crescent appears to have been adopted as an emblem on military flags by the Islamic armies from at least the 13th century, although the scholarly consensus holds that the widespread use of the crescent in Islam develops later, during the 14th to 15th century. The use of such flags is reflected in the 14th-century Libro del Conocimiento and the Catalan Atlas.
The Roman Catholic fashion of depicting Madonna standing or sitting on a crescent develops in the 15th century.
Early modern and modern
The goddess Diana was associated with the Moon in classical mythology. In reference to this, feminine jewelry representing crescents, especially diadems, became popular in the early modern period. The tarot card of the “Popess” also wears a crescent on her head.
Conrad Grünenberg in his Pilgrimage to the Holy Land (1486) consistently depicts cities in the Holy Land with crescent finials. Flags with crescents appear to have been used on Ottoman vessels since at least the 16th century.
Ottoman state symbol started during the reign of Mustafa III (1757–1774) and its use became well-established during Abdul Hamid I (1774–1789) and Selim III (1789–1807) periods.
The association of it with the Ottoman Empire appears to have resulted in a gradual association of the crescent shape with Islam in the 20th century. A Red Crescent appears to have been used as a replacement of the Red Cross as early as in the Russo-Turkish War of 1877/8, and it was officially adopted in 1929.
The identification of it as an “Islamic symbol” is mentioned by James Hastings as a “common error” to which “even approved writers on Oriental subjects” are prone as early as 1928.