OP here. Thanks for these informative posts. I (generally) like local control--it makes things more personal and values the community rather than a distant authority. It helps me understand a bit of the variety in some Jewish practices as well (whether one can eat rice over Passover, for example.)
Still, it makes life a bit more difficult for calendar planning!

This is one of the oldest Muslim American websites articulating this stuff: http://www.moonsighting.com/

It's hard to read but there's a lot of information.

Eid/new month and generally the lunar calendar are supposed to be determined by the sighting of the moon.

Some people take that literally, and want to wait until a community member has actually done the sighting.

Others (the majority, I think) accept using scientific calculations to determine when the moon would be sightable.

Regardless, it's a local thing.

The problem with Eid-al-Adha is that it is comes after the Hajj, the annual pilgrimage to Mecca, and therefore tied with the sightings of the moon there.

This is absolutely fascinating to me. Thanks to all who took the time to reply.

HI,
I am Muslim and share your frustration. the reason they can't figure it out is because Muslim communities decide on Eid following different traditions- some always follow the Saudi dates. Some have the Imam of the Mosque they belong to figure it out, some communities (including mine) ask the naval observatory to do it. The reason it's difficult is also because the sharia is not uniform amongst all Muslims- some say that the moon has to be out for 10 hours, some say 5 etc. . its actually quite complicated unless there is a central authority. My family is from Pakistan and there's a council of Imams who decide and the whole country follows them regardless of sect. I don't really understand why we can't decide on something like that here except that most Muslims who immigrated here did so to be independent of such ruling clerical councils . . . hope this helps. .

I don't know how it is done in a place like the US, but in Saudi Arabia many years ago they were generally Bedouin who were known to be of good character and expert at reading the sky for dead reckoning navigation of the desert. Moon sightings by several reliable witnesses, as accepted by Islamic clerics, were required for the end of Ramadan to be declared. I am not sure how they do it today--for example, whether they would use a physical sighting by an astronomer using a telescope.

Some countries use the Saudi declaration, while others rely on local sightings. Some use the calculated beginning of the lunar month. That could be used in this area I suppose to be able to give advance certainty to the dates, but if the school schedules indicate there is an uncertainty, it would be an indication they are relying on physical moon sighting.

Anonymous wrote:The custom in Islam is to determine when a new month of religious significance begins by moon sighting. That is the physical sighting of the new moon. Astronomy will give you guide as to the probable date, but if reliable witnesses do not sight the new moon, the month will begin a day later. The eid following Ramadan starts at the beginning of a new month, so the moon sightings are followed closely because they determine whether you can end your fast or if you have to go another day. Eid al-Adha, on the other hand, falls on the tenth day of the month, so you would know ten days in advance when it will fall.

Who and where are these reliable witnesses?

The custom in Islam is to determine when a new month of religious significance begins by moon sighting. That is the physical sighting of the new moon. Astronomy will give you guide as to the probable date, but if reliable witnesses do not sight the new moon, the month will begin a day later. The eid following Ramadan starts at the beginning of a new month, so the moon sightings are followed closely because they determine whether you can end your fast or if you have to go another day. Eid al-Adha, on the other hand, falls on the tenth day of the month, so you would know ten days in advance when it will fall.

I'm Jewish; there's a lunar calendar for our holidays. We know when the holidays will fall for the next 100 years (or more, but my calendar is just a 100-year one).
So for Muslim holidays, which also follow a lunar calendar, why don't they know whether Eid will fall on Sunday, Sept. 11 or Monday, Sept. 12 this year?
I wouldn't care except I live in Montgomery County which is closing classes on Monday, Sept. 12 because Eid might fall then. WTF?
Why don't they know? It follows the moon--we know a lot about the moon. Arab astronomers probably were among the first to chart the moon's path.
Thanks for helping me out with this. As you can tell, I'm not thrilled with classes being canceled, but at least I'd like to understand more about the Muslim calendar.