I was curious why Islam uses the lunar calendar. The solar calendar seems more pragmatic because the same date falls in the same season every year. E.g. thanks to the solar calendar, it is easy to know that January 1, 1786 was winter in Copenhagen. It is much harder to derive the season in different geographic locations based on a lunar date.
The only advantage to the lunar calendar I can think of is to diversify the difficulty of the Ramadan fast, to make it easier in some years and harder in others. But are there any other benefits of and reasons why Islam uses it?
Thinking more about it, lunar calendar is more easy to follow than the solar calendar. People of all places/ways/styles/advances/etc can easily count days just by looking at varying shapes of the moon. As sun does not changes its appearance, dates cannot be counted just by looking at the sun and needs external astronomical means for this. This is one of the reason that all civilizations used lunar calendar from earlier times.
Actually, Islam also uses sun time keeping! Times of various salah is derived on the position of the sun, as this can be done easily.
Hence, both sun and moon are used for Islamic purpose -)
By the time of Islam the solar calendar was widely accepted as the most accurate measurement of time. Arabs didn’t need an accurate calendar because their civilisation was based on trade rather than agriculture which needs accuracy to sow reap and harvest etc. imo the Islamic calendar was an Arab calendar. The earliest civilisations and Neolithic sites were constructed to measure time and to figure out the equinoxes which were redundant in a trading culture. Knowing this why would Allah not correct the Arabs to keep a more accurate calendar?
I looked into this, and my research showed that the original Islamic calendar used by the Prophet (sas) was lunisolar -- like the Jewish calendar, but with Ramadan containing to the autumn equinox. Given the 11-day gap between the solar year and twelve lunar months, the Prophet (sas) added a leap month to the coming year whenever the autumn equinox fell in the last eleven nights of Ramadan ("the witr of the last ten"). By this method, he kept the equinox in Ramadan. Lailat al-Qadr is the autumn equinox.
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