Most of you have already noticed that Turkish flag and Ottoman flags have a crescent. Because both in Turkish Republic and Ottoman Empire the dominant religion is Islam.
First of all crescent is not a symbol of Islam but associated with this religion. This symbol was even used by ancient civilations dating back to 4000 years.
In Islamic time social life was regulated by moon calender to calculate especially time of Ramadan.
When crescent occured in the sky on the 29th of the month they were announcing of Ramadan arrival and when they saw it last time in the morning they started to fast until they saw it in the evening, from sunrise to sunsut today.
In polytheistic pagan time in Arabia, Moon God was named as Allah as well, so prophet Muhammed used the same name for a monoteistic religion creator to persuade the people to convert in Islam.
Also prophet was considered as a moonlight getting it source from the Sun, considered as God.
Now you will remark better the crescents on the top mosques’s domes during your trip in Turkey!