Why not adopt CONJUNCTION as the basis for starting the month?
Let us examine the conjunction as a possible basis of starting a month. Remember, the conjunction can occur at any time between 24 hours. Suppose the conjunction occurs at 11pm Universal Time (Sunday), then at that moment Makkah time is 2am (Monday). Should England start the month on Monday and Saudi Arabia start the month on Tuesday? Now, if someone says that let us make Makkah as our basis and whatever day in Makkah, the conjunction occurs the next day the new month starts. The problem with this is that if conjunction occurs at 0:01am (Monday) of Makkah time then at that moment it is 2:01pm (Sunday) in Hawaii. Should Hawaii start the month on Monday and Saudi Arabia start the month on Tuesday? Look at another case: Suppose the conjunction occurs at 11:59pm (Sunday) Makkah time then at that moment it is 5:59am (Monday) in Tokyo. Should Japan start the month on Tuesday and Saudi Arabia start the month on Monday? If someone says, ignore what time it is in other locations of the world, j
