A Fast That Migrates Through the Calendar

Ramadan is fixed to the Islamic lunar calendar, which runs about eleven days shorter than the solar year and carries no leap month to correct the drift, so the fasting month cycles slowly through every season across roughly a thirty three year span. Early Muslim communities in Arabia fasted through a fairly consistent climate; Muslims today may fast through a summer with sixteen or more hours of daylight in northern latitudes one decade and a mild winter fast a decade later, a variation the earliest Muslim community did not face in the same way. Some scholars record an earlier fast connected to the Jewish Day of Atonement, Ashura, kept before Ramadan fasting was made obligatory and afterward continued as a separate, voluntary fast rather than dropped.

Determining when the month begins has its own long running dispute: the classical method requires an actual sighting of the new moon, reported by trustworthy witnesses to local authorities, while modern astronomical calculation can predict the moon's position precisely in advance. Many countries and communities have adopted calculation for convenience and consistency, while others insist sighting is what tradition requires, so the fast commonly begins on different days in different countries in the same year. For Muslims living at extreme latitudes where the sun barely sets or barely rises, scholars have issued rulings permitting the fast to follow the timing of the nearest moderate latitude or of Mecca itself.