|from the original on 9 September 2017||not based on observation , which results in differences of typically one or even two days between countries using such schema and those that use lunar sightings|
|For example, the used in Saudi Arabia was reformed several times in recent years||There are various schemas for calculating the i|
Robert Harry van Gent, 11 June 2011 at the• For an observation-based calendar, a sighting of the at sunset of 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.
|Islamic Crescents' Observation Project, 10 May 2012 at the ; seen on 6 December in Algeria, Iran, Saudi Arabia, South Africa||1442 Using Part of on• A day in the Islamic calendar is defined as beginning at|
|All religious duties, such as , in the month of , and , and the dates of significant events, such as celebration of holy nights and , are calculated according to the Islamic calendar||sunset, last day of Dhu al-Hijjah Ends• While some organizations prefer determining the new month and hence the new year by local sightings of the , most Islamic institutions and countries, including , follow calculations to determine future dates of the Islamic calendar|
For example, 1 Muharram 1432 was defined to correspond to 7 or 8 December 2010 in depending on the country.6
|Gregorian correspondence [ ] Main article: Since the Islamic is eleven to twelve days shorter than the as counted by the , the Islamic New Year does not occur on the same day of the Gregorian calendar every year||from the original on 12 November 2018|