For centuries, the sighting of a crescent moon has signaled the end of Ramadan, the holy month of fast and prayer for Muslims.
This year, the sight was obscured in some parts of the world by the sun’s glare during the total solar eclipse, delaying some Islamic communities’ declaration of Eid al-Fitr, the celebration marking the end of the fast. Although only a narrow band of North America experienced a total eclipse, the phenomenon reduced lunar visibility elsewhere, experts said.
In Kerala, a state in southern India, the new moon was spotted on Tuesday, but it was not seen in the capital of New Delhi, so Muslim communities in India will celebrate Eid one day apart.
In Saudi Arabia, an authority on religious observances for many Muslims, the government called on all Muslims throughout the kingdom to look for the crescent moon on Monday. When it was not reported seen, the Supreme Court declared on Tuesday that Eid would be celebrated beginning on Wednesday.
Countries with large populations of Muslims, and Muslims around the world, use the traditional Hijri calendar to mark religious events. Each month of that calendar begins with the sighting of the early crescent moon, and the holy month of Ramadan begins at the start of the ninth month.
Eid is traditionally celebrated the day after a new moon is seen, either with the naked eye or a telescope. According to the European Council for Fatwa and Research, the moon must appear at sunset, at least five degrees above the horizon.
Because the crescent moon can be difficult to see, and its position above the horizon can be hard to independently calculate, some Muslim communities rely instead on a computational method, according to Basharat Saleem, executive director of the Islamic Society of North America.
“In the old days, and still in some parts of the world, people would do moon-sighting, look to be able to visually see it,” Mr. Saleem said. “Nowadays with calculations and precise measurements, it has become easier.”
These customs go back centuries. But the exact period of Ramadan varies from place to place because it depends on a range of factors, including who observes the moon and how, and whether the sky is clear or cloudy at the time.
While some Muslim communities rely on the sighting of the moon, others use a lunar calendar to determine when Ramadan begins and ends.
The Islamic Society of North America, a nonprofit based in Plainfield, Ind., and one of the largest Islamic organizations in the United States, follows NASA’s lunar calendar, which means celebrating Eid on Wednesday, too.
“We know the moon is visible without having to see it,” said Muhammad Safder, a member of the board of Masjid al-Taqwa in Indianapolis, a city that fell in the eclipse’s narrow path of totality on Monday.
As Central Indiana plunged into darkness during the solar eclipse, Mr. Safder and about 60 others entered the mosque for a special prayer.
According to the Hadith, the sacred Islamic text, there was an eclipse around the death of the Prophet Muhammad’s son, Ibrahim.
The prophet reassured followers that the eclipse had not caused Ibrahim’s death, but was simply a “miracle of God” for which he recommended a prayer, Mr. Safder said.
“It was kind of dark all of a sudden,” Mr. Safder said of the eclipse. “As we finished praying, it seemed like the morning was starting. It was spiritually uplifting, especially while fasting.”
