RRI.CO.ID, Jakarta – Alaska, the westernmost U.S. state, has become a topic of discussion among Indonesian Muslims, especially over the past weeks before the holy fasting month of Ramadan. A new system, adopted by one of the country's largest Islamic organizations for the first time this year, is the reason.

Muhammadiyah is one of Indonesia's largest Islamic organizations, with the official website stating its membership is estimated to range "between 30 and 40 million". Known for its social activities, it established thousands of schools, as well as hundreds of universities and hospitals.

The organization is also known for its religious teachings, which widely support the modernist view of Islam. One of its views is regarding the determination of important Islamic dates, such as the beginning of Ramadan, Eid al-Fitr on 1 Shawwal, and Eid al-Adha on 10 Dhu al-Hijjah.

Muhammadiyah preferred calculations (hisab) of moon visibilities over the traditional moon sightings (rukyatul hilal) to set those dates. For decades, it used the local-based calculation method known as hisab hakiki wujudul hilal.

In 2025, Muhammadiyah launched the Unified Global Hijri Calendar, an attempt to unify the Islamic calendar worldwide, as the first day of each month often differs by location. It is adopted from an international conference in Turkiye in 2016, which aims to foster global Muslim unity and unify religious and civil timekeeping.

The calendar system has parameters that must be met for a day to be considered the start of a new month. The entire Earth is regarded as a single coverage area, rather than a country or local region, as in traditional methods.

A new month begins when the moon is calculated to be visible with a minimum moon elongation of 8° and a minimum crescent height above the horizon at sunset of 5°, somewhere on Earth before midnight GMT. If the criteria are met after midnight, a new month starts if the calculations for the crescent moon are fulfilled somewhere on Earth after midnight GMT, and a moon conjunction has occurred in New Zealand before dawn.

The astronomical calculation in the calendar indicates that the crescent moon visible in Bethel, Alaska, on Tuesday evening, 17 February local time, met the criteria. Thus, according to Muhammadiyah's view of the calendar, 1 Ramadan of the current Hijri year of 1447 falls on 18 February.

This differs from the Indonesian government, which decided Ramadan starts on Thursday, 19 February. 2026. The government's decision was based on both moon sightings and calculations, with criteria agreed upon within MABIMS – the forum of ministers of religious affairs of Brunei, Indonesia, Malaysia, and Singapore.

This difference continues the long-running debate among Indonesian Muslims over when they should do the special worship in the Islamic holy days. Moreover, the moon is yet to appear visible in the Indonesian sky as of Tuesday.

However, both Muhammadiyah and the Indonesian government have also long called for tolerance to respond to this. Chairperson of Muhammadiyah, Haedar Nashir, invited all elements of the nation to address the differences with maturity.

"Today we begin fasting, even though there might still be differences among us regarding the start of our Ramadan 1447 Hijri fasting. So, when we differ, let us go through it with tasamuh (tolerance), intelligence, and our collective maturity," Haedar said in a reflection video released on Wednesday, 17 February 2026.

A similar call was also made by Indonesia's Minister of Religious Affairs, Nasaruddin Umar, in a press conference after the "Isbat Session" – a date-determining session – in Jakarta on Wednesday. He emphasized that Indonesian Muslim society has a long history of managing diversity, including in determining the start of the Hijri month.

"If there are among our citizens, fellow Muslims, who might do things differently according to their respective beliefs, we also appeal to all members of society: let these differences not cause us to be separated or differ in a negative sense, let us make these differences a beautiful configuration," he said.