Questions about calendars. The Jewish calendar is a lunisolar calendar that determines the dates of Jewish festivals.

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1answer
208 views

Making up a synagogue calendar manually is tedious work. Which software can do the calculations automatically?

Lots of synagogues print up a customized calendar every year. (Sample.) Such a calendar includes shul-specific information (e.g. service times and maybe a weekly class or two) and general information ...
15
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2answers
1k views

How does one “add a year” in the Hebrew calendar?

I'm trying to support the Hebrew calendar in my Noda Time project, and need to support an operation of "add a year" - or more generally, answer the question of "Given an original date and a target ...
13
votes
1answer
238 views

Why does the torah give us exact dates for the flood?

This question asks why the flood didn't end on the 18th of Cheshvan (one year after the start). My question is more basic: why does the torah give us precise dates here at all? Bereishit 7:11 tells ...
10
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3answers
295 views

9 Days of Chanukah?

All Yomim Tovim we celebrate in Chutz Laretz an extra day because of A safek, why do we not do the same for Chanukah?
7
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1answer
278 views

Where in tanach are the months named

In megilas esther the months of the year are called out by name. For example the 12th month is called adar. Is there anywhere else in tanach that months are referred to by name?
7
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2answers
187 views

“לְחֹדֶשׁ שְׁנֵים עָשָׂר” in the Megillah and Al Hanisim

As I was reading Al Hanisim this year, something odd struck me "לְחֹדֶשׁ שְׁנֵים עָשָׂר" - the 12th month. What struck me was that this year is a leap year so we actually celebrated Purim in the ...
7
votes
1answer
92 views

Getting a late start on being Maavir Sedra for the year

I remember hearing when I was younger that ואלה שמות - is Roshei Teivos V'Chayav A'dam L'haavir H'sedra S'htayim M'ikra V'echod T'argum. If someone who has not been Maavir Sedra so far this year is ...
6
votes
4answers
313 views

Is it permissible to write the English/secular date?

Is it permissible to write the secular/Christian date? Example: On a letter (bad example but you get what I mean). Some conceivable issues: We're told "this month (Nisan) shall be for you the head ...
5
votes
2answers
141 views

Time Parameters of Mishenichnas Adar Marbin B'Simcha

Is "Mishenichnas Adar Marbin B'Simcha" just for the month of Adar, and then you take a step down in simcha for Nisan? Or are you supposed to raise your level of simcha and stay there until Av, when ...
5
votes
1answer
89 views

Why did people date divorce documents according to the Greeks?

According to this article on Jewish Encyclopedia, the conventional Jewish system of dating documents in the Middle Ages (a system called "מנין שטרות") was related to the accession of Seleucus I, the ...
5
votes
1answer
346 views

Rambam's method for calculating the conjunction of the moon (and sun)

I think I'm missing something basic here... The Rambam, in Hilchot Kiddush Hachodesh (6:3) says that the interval between one conjunction to the next is is 29 full days, 12 hours of the 30th day, and ...
5
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1answer
210 views

When do we change back the ark-cover etc from white to the rest-of-the-year colour?

When do we change back the proches (ark-cover) etc from white to the rest-of-the-year colour? I would have thought right after Simchas Torah or possibly Isru Chag?
5
votes
0answers
155 views

Late sunset times and Jewish observance

This question is distinct from other questions which ask how and when to begin Shabbat, etc. when there is no sunset. I am asking about places in which sunset occurs very late during certain times of ...
4
votes
2answers
153 views

Why not say tachanun until 2 Cheshvan?

It's recorded in most siddurim I've used that some people have the custom to skip tachanun on Isru Chag (the day after Sukkos), and start again the day after, while others don't resume saying it until ...
4
votes
1answer
47 views

How accurate is the Molad?

To the best of my knowledge the Molad is every 29.5 days + 793 Chalakim. Is there any information showing if the current Molad calculation is accurate scientifically? If it is off by how much is it ...
4
votes
0answers
51 views

Yakkov living in Egypt 17 years - connection to 210 years of servitude

Parshas Vayechi starts off that Yaakov lived in Egypt for 17 years. I was thinking that 17 years x 12 months = 204 months. Usually in 17 years there are 6 leap years which would increase the total ...
4
votes
2answers
352 views

Halachically skipping Purim

There have long been 'legends' of various liberal figures in Judaism, including Yeshayahu Leibovitz (brother of Nechama Leibovitz) that would 'skip' Purim. On the 14th of Adar they would be sure to be ...
4
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1answer
470 views

When and why did we start reading the Parshat Hashavua?

My question is twofold: When did we start reading a new parsha (torah portion) every week? Why did we start reading a new parsha (torah portion) every week?
4
votes
1answer
728 views

Mashiv HaRuach - V'Sain (veten) Tal Umatar

Why do we start saying Mashiv HaRuach on Shemini Atzeres yet we do not say V'Sain Tal Umatar until Dec 4 / Dec 5 (In Chutz L'Aretz)? Why should they not be on the same day when they are similar ...
3
votes
2answers
52 views

Why isn't Shabat haGadol held on the 10th of Nissan?

Why is Shabat haGadol celebrated based on day of the week (Shabat) and not day of the month, if it happened on the 10th of Nissan? Most other days of commemoration in Judaism are celebrated by a day ...
3
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3answers
172 views

Is it ok to celebrate New Years Eve?

Is it ok to celebrate New Years Eve? Which (orthodox, not modox or non-orthodox) rabbinical authority was against it and which one was in favor of it (if such opinions exist).
3
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2answers
303 views

Hebrew Calender API/Library in PHP or Javascript to add days, month or years to Julian date

I have a web project where I need a function either server-side using php or client-side using javascript where I can pass in a Georgian date and have month(s) or years added to it according to the ...
3
votes
4answers
1k views

Where can I find a chart of the Mishna Yomit (daily Mishna learning)?

Where can I find a chart of the Mishna Yomit (daily Mishna learning) - either online or offline?
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2answers
117 views

Secular Names for Days of the Week

Is there a problem using the secular names for the days of the week? If so, is it 1) because they originally come from Polytheistic gods or 2) simply because the people forbidding them are of the ...
2
votes
1answer
115 views

What sources are there for the meaning of Yom HaMeyuchos (2nd Sivan)?

Ohr Sameach gives the chronology according to Rashi of the giving of the Torah. Early the following morning, the 2nd of Sivan, Moshe goes up Mt. Sinai for the first time. He is instructed to ...
2
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2answers
107 views

On which day in Teveis did this happen?

In Megilas Esther 2:16 it mentions that Esther was taken in Teveis to Achasverosh's palace. Does anyone know on which day of the month this happened?
1
vote
1answer
28 views

When do sefardim begin reciting selihot?

Since rosh hodesh Elul is a mini-holiday do you need to wait till the day after rosh hodesh or do sefardim begin saying selihot on the first of Elul?
1
vote
1answer
71 views

Why do we abbreviate the Jewish year to the hundreds column?

The current Jewish year is 5774 however it is popularly abbreviated as 774 - תשע״ד. I would like to know why this abbreviation was adopted. I realize that to write out the number 5,000 would require ...
1
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1answer
142 views

Is Jewish birthday the same every lunar year

I understand the Jewish birthday is calculated on the lunar year, which could cause the birthday to drift back and fourth along the lunar calendar. But supposing the child was born, say, first day of ...
1
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0answers
52 views

Why are the daily tehilim divided as they are?

How were the daily starting and ending points for weekly and monthly readings of all of tehilim chosen? Are they just chosen to make them all approximately the same length, or are there specific ...
0
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1answer
45 views

Why is Rosh Hashana two days in Jerusalem?

Rosh Hashana is the only festival celebrated for two days even in Jerusalem, since there was a possibility that witnesses for the new moon would come in the middle of the day and the Beis Din would ...