Why does the conversion of a date to the Muslim calendar isn the same between different software ?
The Muslim calendar is a lunar calendar Composed of 12 months of 29 or 30 days each and where the 9th month is the Ramadhan month. So it is based on the moon’s phases and starts the first evening after the new moon, when it reappears just after sunset. The dates and hours of the new moons are calculated each year by the Bureau of Longitudes in Paris, and these dates and times are used in RamCal and in some countries like Turkey. But in other countries like Saudi Arabia or France, the first crescent must be observed with naked eyes by a faithfull. So in case of bad weather, there may be a shift of several days !
