Why is Shavuot one day in Israel, two elsewhere?

[Outpits]

In this thread on Staff Reports
Thread on Orthodox Jewish Sabbath
it was noted that the Jewish holiday of Shavuot (“Pentecost”) is a two-day festival in the United States, but it is only a one-day festival in Israel. The comment by member Keeve pointed this out, but then stated, “The reasons why it is one day in Israel and two days elsewhere gets complicated.”

Is there a relatively simple explanation?

I do appreciate that Orthodox Jewish posters will be about to celebrate this holiday, so I am content to wait.

[Anne_Neville]

@Outpits

Is there a relatively simple explanation?

Here you go.

Basically, the Jewish calendar used to be a lunar calendar that relied on someone actually seeing the new moon. You can get a pretty good idea of when that’s going to happen, but you can’t know for sure in advance that someone is actually going to see the new moon on such-and-such a date. (And no, I don’t know what they did if it was overcast throughout Israel for many days around the time of the new moon)

There’s another problem, too- the sighting of the new moon has to be reported to the Sanhedrin in Israel to be official. Then the Sanhedrin sends out word to all the Jewish communities in the world that the first day of the new month falls on such-and-such date. Jewish communities in Israel will probably get the word in time for the holiday, but the far-away communities elsewhere in the world might not. So the communities outside Israel hedged their bets by celebrating the holiday for two days, figuring they would be more likely to get the right day that way.

The Jewish calendar no longer relies on someone actually sighting a new moon (now, when we want to know when the first day of a new month or a holiday is, we Google it). But by the time the calendar was made independent of sighting a crescent moon, celebrating holidays for two days had become a tradition in Jewish communities outside of Israel, so they kept doing it. Custom and tradition are given a lot of weight in Judaism, at least as much as what the Bible actually says.

[Outpits]

@Anne Neville

Here you go.

Basically, the Jewish calendar used to be a lunar calendar that relied on someone actually seeing the new moon. You can get a pretty good idea of when that’s going to happen, but you can’t know for sure in advance that someone is actually going to see the new moon on such-and-such a date. (And no, I don’t know what they did if it was overcast throughout Israel for many days around the time of the new moon)

There’s another problem, too- the sighting of the new moon has to be reported to the Sanhedrin in Israel to be official. Then the Sanhedrin sends out word to all the Jewish communities in the world that the first day of the new month falls on such-and-such date. Jewish communities in Israel will probably get the word in time for the holiday, but the far-away communities elsewhere in the world might not. So the communities outside Israel hedged their bets by celebrating the holiday for two days, figuring they would be more likely to get the right day that way.

The Jewish calendar no longer relies on someone actually sighting a new moon (now, when we want to know when the first day of a new month or a holiday is, we Google it). But by the time the calendar was made independent of sighting a crescent moon, celebrating holidays for two days had become a tradition in Jewish communities outside of Israel, so they kept doing it. Custom and tradition are given a lot of weight in Judaism, at least as much as what the Bible actually says.

Thank you for the post and the link

[si_blakely]

Eid - the Islamic Festival to celebrate the end of Ramadan - is also based of a lunar sighting. I used to have team members ask for either Thursday or Friday off (for example) to celebrate it.

Si