MUHAMMADIYAH.OR.ID, YOGYAKARTA – In a recent online article published on Tuesday (May 13), a member of the Muhammadiyah Council for Religious Opinion and Tajdid Susiknan Azhari highlighted the importance of clearly defining when a new day begins in the proposed Unified Global Hijri Calendar. For Susiknan, this idea is not just a technical detail, but a crucial foundation for building global unity among Muslims.
The global Hijri calendar is part of a broader vision to create one unified Islamic calendar that allows Muslims around the world to observe key religious events such as Ramadan, Eid al-Fitr, and Eid al-Adha on the same date. The aim is to foster a deeper sense of wahdatul ummah (the unity of the global Muslim community).
The calendar applies a new approach to determining the start of a new Islamic day. Rather than relying on local moon sightings, it uses what’s known as the “First Crescent Visibility Point”, the earliest location on Earth where the new moon becomes visible, based on specific astronomical criteria: a minimum elevation of five degrees and an elongation of eight degrees. By using global astronomical events like ijtima’ (the moon-sun conjunction), the calendar sets a unified Hijri date that applies to all regions.
For example, if the moon becomes visible before midnight UTC in a place like New Zealand or the United States, the next day is considered the start of a new Hijri month for Muslims worldwide.
Susiknan pointed to records from the book “Kalender Islam Global” (Global Islamic Calendar) by Sriyatin Shodiq and Ainul Yaqin al-Falaky. They stated that several crescent sightings are listed: in Sha’ban 1487 AH (2064 CE), the crescent was first seen in Wellington, New Zealand; in Ramadan 1469 AH (2046 CE), it appeared first in Yogyakarta, Indonesia; and in Ramadan 1521 AH (2097 CE), Los Angeles, USA became the first point of visibility.
This approach marks a shift from the MABIMS New Moon Visibility Criteria, which is limited to certain regions. The unified global Hijri calendar, in contrast, applies globally—from New Zealand in the east to the Americas in the west.
Practically speaking, the unified global Hijri calendar means that Muslims around the world would follow the same Islamic date, even if their local clocks differ. If, for example, the first day of Ramadan is set to begin on a Saturday based on a crescent sighting in the Pacific Ocean, Muslims everywhere would observe the first day of Ramadan on that same Saturday—even if it’s still Friday evening in some places like the United States.
The goal is to create consistency in collective worship, in line with a hadith from Prophet Muhammad (peace be upon him) reported by at-Tirmidhi: “The fast is the day the people fast, the breaking of the fast is the day the people break their fast, and the sacrifice is the day the people sacrifice.”
At the same time, the unified global Hijri calendar doesn’t interfere with local religious practices. Daily acts of worship, such as prayers and taraweeh, would still begin at sunset according to each local time zone. The calendar’s role is administrative and collective, not meant to replace how Muslims follow time for daily rituals.
This is similar to how the Gregorian calendar works: the date is the same across the world, but people still follow local time.
For Susiknan, the unified global Hijri calendar is more than just a calendar project. It’s a joint effort based on shared values and mutual understanding. He stressed that making this vision a reality will take wide public engagement, active dialogue among scholars, and cross-regional cooperation so that the calendar can be accepted and implemented smoothly.
“The unified global Hijri calendar is not just about astronomy or calculations. It is a collective effort to realize the spirit of Islamic brotherhood across the globe,” said Susiknan.
