Can we achieve a global Islamic calendar that could unite the whole world for same dates for the beginning of every Islamic month?
If sighting is required we cannot have Global Islamic Calendar. To achieve a pre-calculated Global Islamic Calendar, if Ulemaa of the world accept the need for it, a suggested convention could be to make Makkah a convention point, where if the moon is born before sunset, the month begins after sunset, and if the moon is born after sunset then the month begins the following evening. This would require two calculations; 1) New Moon Birth, and 2) Sunset in Makkah on that date. A preferrable convention could be that if the moon is born before 12:00 UT, then the month begins at sunset of that day everywhere in the world. This requires only the calculation of new moon birth, which is well known. This convention has a strong basis of the visibility that somewhere on the globe the moon would be definitely visible given clear horizon, because the age of the moon would be 18 hours at sunset on a point just to the east of the International dateline if the moon birth took place before 12:00 UT. As
