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Comment by zarzavat | Hacker News Reader

> even if lunar time is well known

The date of Ramadan is not well known because it's based on being able to see the moon from the local position on Earth. If the sky is particularly overcast for instance, then you cannot see the moon, regardless of where the moon is.

This presents problems for implementation of the calendar into the workings of a nation state. Many countries that adopt the Islamic calendar officially use an approximation, a pre-calculated date based on the moon's predicted visibility at a particular position.

The Islamic calendar is therefore not really one calendar, but two: the observational Islamic calendar and the predicted calendar, and both have a dependence on a location from which either real observations are made, or predicted observations are made.

I don't know how Morocco or Gaza do it.

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> The date of Ramadan is not well known because it's based on being able to see the moon from the local position on Earth.

Note to self, look up what Islamic scholars think should be done about Ramadan on a moon base.

Not quite a moon base, but for Muslims on the ISS:

> the Malaysian government called a gathering of 150 Islamic legal scholars, scientists, and astronauts to create guidelines for Dr. Shukor. The scholars produced a fatwa, or non-binding Islamic legal opinion, intended to help future Muslim astronauts, which they translated into both Arabic and English. They wrote that in order to pray, Muslims in space should face Mecca if possible; but if not, they could face the Earth generally, or just face “wherever.” To decide when to pray and fast during Ramadan, the scholars wrote, Muslims should follow the time zone of the place they left on Earth, which in Dr. Shukor’s case was Kazakhstan. To prostrate during prayer in zero gravity, the scholars stated that the astronaut could make appropriate motions with their head, or simply imagine the common earthly motions.

I’m not an Islamic scholar (or a Muslim at all), so this is just speculation, but my guess is that if it were a permanent settlement, with people being born and living their whole lives on the moon base (so “where they left earth from” is not meaningful), they’d probably just settle on one permanent Earth time zone to follow; presumably either that of Mecca, or that of whatever country on Earth (if any) owns the base.

Prayer and pointing to Mecca seems pretty simple on the moon - but if Ramadan is based on when you can see the moon, it seems that Ramadan would start as soon as the person in charge walks by a window.

Yep! I think for that case the "follow the time zone of some particular place on Earth" rule would apply.

Moon-dwelling Muslims would go by the phases of Earth, if they wanted to match Earth timing but not rely on communication with Earth. The Earth as seen from the Moon exhibits the opposite phase as the reverse. Ramadan would begin when the Moon-dweller sees the Earth as being just past full. If you wanted, you could synch it with a particular timezone on Earth, by watching for when that location on Earth (Mecca or whatever) just rotated past the terminator so it experienced sundown. (Of course none of this can be directly observed if you're on the far side.) (And I get your joke about seeing the moon when you're on it; this is the practical alternative.)

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