Explainer

How Do We Know When It’s Ramadan?

The United States won’t halt its military campaign in Afghanistan during the Muslim holy month of Ramadan, but Colin Powell says war planners will be “sensitive to the fact that this is an important religious period,” the Wall Street Journal reports. When will this new sensitivity begin? Slate says Ramadan starts “around Nov. 17.” Other publications say it begins “in mid-November” or that it is “expected to begin Nov. 17.” Why the uncertainty? How will we know when it’s Ramadan?

Ramadan follows Shaban, the eighth month of the Islamic calendar. Unlike, say, January, Ramadan and Shaban do not have a fixed number of days. Each month can have 29 or 30 days, depending on when the first sliver of the crescent moon is sighted by the naked eye. If, on the 29th day of Shaban, the crescent moon is sighted, Ramadan has begun, and Muslims begin fasting that morning. If the moon isn’t sighted that night, Shaban lasts 30 days, and Ramadan begins the next day (whether the moon has been sighted or not).

This year, Ramadan is expected to begin at sunset Nov. 16, with fasting beginning the morning of Nov. 17. But as this U.S. Naval Observatory site points out, the day isn’t certain. The first crescent moon’s visibility can depend on sky conditions, altitude, the experience of the observer, and the limits of human vision, among other factors.

The start of Ramadan can also vary among Muslim communities. Two mosques next door to each other could follow two different sightings of the crescent moon. More conservative Muslims who incline toward the Wahabbi school will honor the moon’s sighting in Saudi Arabia, while others insist that the moon has to be seen in their own country.

Click  here for a glossary of Islam.

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Explainer thanks Osman Bakar of Georgetown University’s Center for Muslim-Christian Understanding and Juan Cole, editor of the International Journal of Middle East Studies.