historically, the moon and star in islam are best known as a symbol for the star and crescent empire.
historically, the moon and star in islam are best known as a symbol  for which empire?
star and crescent
the star and crescent is an iconographic symbol used in various historical contexts but most well known as a symbol of the ottoman empire. it is often considered as a symbol of islam by extension, however is denied as the religion bears no symbol. it develops in the iconography of the hellenistic period (4th–1st centuries bce) in the kingdom of pontus, the bosporan kingdom and notably the city of byzantium by the 2nd century bce. it is the conjoined representation of the crescent and a star, both of which constituent elements have a long prior history in the iconography of the ancient near east as representing either sun and moon or moon and morning star (or their divine personifications). coins with crescent and star symbols represented separately have a longer history, with possible ties to older mesopotamian iconography. the star, or sun, is often shown within the arc of the crescent (also called star in crescent, or star within crescent, for disambiguation of depictions of a star and a crescent side by side); in numismatics in particular, the term crescent and pellet is used in cases where the star is simplified to a single dot.
star and crescent
those who claim that allah is a pagan deity, most notably the moon god, often base their claims on the fact that a symbol of the crescent moon adorns the tops of many mosques and is widely used as a symbol of islam. it is in fact true that before the coming of islam many "gods" and idols were worshipped in the middle east, but the name of the moon god was sîn, not allah, and he was not particularly popular in arabia, the birthplace of islam. the most prominent idol in mecca was a god called hubal, and there is no proof that he was a moon god. it is sometimes claimed that there is a temple to the moon god at hazor in palestine. this is based on a representation there of a supplicant wearing a crescent-like pendant. it is not clear, however, that the pendant symbolizes a moon god, and in any case this is not an arab religious site but an ancient canaanite site, which was destroyed by joshua in about 1250 bc. ... if the ancient arabs worshipped hundreds of idols, then no doubt the moon god sîn was included, for even the hebrews were prone to worship the sun and the moon and the stars, but there is no clear evidence that moon-worship was prominent among the arabs in any way or that the crescent was used as the symbol of a moon god, and allah was certainly not the moon god's name.
allah as a lunar deity