And today's unusual enquiry was ....

[jnb]

At the observatory today I picked up a phone call from a woman who had been having, as she put it, a heated argument with her friends over the timing of the new moon because they all wanted to know when ramadam was going to end.

the only thing is that while I could tell her the exact time of the new moon I'm sure there is something to do with it not being the moment of new moon but when it is visible. So she went away with smugness points for having the time right but had to concede her friends might be right on the visibility. We were both confused over what happens if you don't have a clear horizon but someone else does.

 

[Peter Drew]

We have a number of enquiries from Muslems each year during Ramadam for the same reason. It appears that it is required for them to see the new Moon in order to end their fast. As we all know, it takes some time for the Moon to be seen by the naked eye following statisical new Moon, particularly if it is a cloudy period. I understand that nowadays it is acceptable to be in contact with someone that has seen it.

[JeremyS]

One of the tasks of the astronomers at the Helwan Observatory near Cairo in the early part of the 20th century was to provide an official  Ramadan moon spotting service.

[westmarch]

31 minutes ago, JeremyS said:

One of the tasks of the astronomers at the Helwan Observatory near Cairo in the early part of the 20th century was to provide an official  Ramadan moon spotting service.

Doesn’t sound that different from the arguments that still go on about when we should have Easter. 

[JeremyS]

2 minutes ago, westmarch said:

Doesn’t sound that different from the arguments that still go on about when we should have Easter.

Not exactly: you can calculate the date Easter. Whilst it's based on the time of the full moon, it doesn't depend on the sighting of it.

[westmarch]

Just now, JeremyS said:

Not exactly: you can calculate the date Easter. Whilst it's based on the time of the full moon, it doesn't depend on the sighting of it.

Unless you are Orthodox Christian, it still has not been resolved.

https://www.catholicnewsagency.com/news/will-pope-francis-change-the-date-of-easter-87684

 

[JeremyS]

4 minutes ago, westmarch said:

Unless you are Orthodox Christian, it still has not been resolved.

Actually that's a different discussion.  Eastern Orthodox and Oriental Orthodox Churches continue to use the Julian calendar, whereas the western world uses the Gregorian calendar. In both cases it's a calculation based on the moon and not a sighting. 

[westmarch]

I think in all cases it is really a calculation based on belief.

[jnb]

2 hours ago, Peter Drew said:

. I understand that nowadays it is acceptable to be in contact with someone that has seen it.

That might account for her followup question which was could we see it from the observatory.

 

[Demonperformer]

Easter is the first sunday after the first full moon after the spring equinox. Tied into the Jewish festival of Passover.

[JeremyS]

10 hours ago, westmarch said:

I think in all cases it is really a calculation based on belief

I certainly believe it's possible to calculate the date of Easter, as Demonperformer has shown.

However, from your comments, I suspect you are making another point about belief and religion, so in view of the guidelines for the Forum, I respectfully won't engage.

[Demonperformer]

Actually, my previously quoted formula is slightly incorrect. It is the sunday after the first saturday after the first full moon after the spring equinox.

[Gina]

I knew it was complicated.  So I look in my diary or online ?