Islamic New Year

While some Islamic organizations prefer determining the new month (and hence the new year) by local sightings of the moon, most Islamic institutions and countries, including Saudi Arabia, follow astronomical calculations to determine future dates of the Islamic calendar. There are various schemas for calculating the tabular Islamic calendar (i.e., not based on observation), which results in differences of typically one or even two days between countries that use such schemes and those that use actual lunar sightings. For example, the Umm al-Qura calendar used in Saudi Arabia was reformed several times in recent years. The current scheme was introduced in 1423 AH (15 March 2002).

A day in the Islamic calendar is defined as beginning at sunset. For example, 1 Muharram 1432 AH was defined as corresponding to 7 or 8 December 2010 CE in civil calendars (depending on the country). For an observation-based calendar, a sighting of the new moon at sunset on 6 December would mean that 1 Muharram lasted from the moment of sunset of 6 December to the moment of sunset of 7 December, while in places where the new moon was not sighted on 6 December 1 Muharram would last from the moment of sunset of 7 December to the moment of sunset of 8 December.

Alternative date

Twelver Shia Muslims believe the Islamic new year is the first of Rabi' al-Awwal rather than Muharram, due to it being the month in which the Hijrah took place. This has led to difference regarding description of the years in which some events took place, such as the Muharram-occurring battle of Karbala, which Shias say took place in 60 AH, while Sunnis say it took place in 61 AH.