14
votes
Accepted
When is a convert's Hebrew birthday?
Dinonline answers,
Although a Ger is considered to be “born anew” when becoming Jewish,
this is a halachic concept that relates to family relationship and the
like, and it is not a “biological ...
- 13.8k
13
votes
Accepted
Does Passover occur on the first full moon after the equinox?
Your question and DoubleAA's comment on my original answer have inspired me to do some research and learn some really fascinating information about the Hebrew calendar.
First, some background ...
- 24.7k
13
votes
Changing the day of Shabbos?
While the Jewish holidays are controlled by the Sanhedrin (though, notably, they are not controlled by non-Jewish governments, and even the Sanhedrin's control is bound by divinely received rules), ...
- 17.7k
12
votes
Accepted
Declare a leap year due to coronavirus?
There are two problems, both are discussed (among others) in Sanhedrin 11a. The first is that you need a Sanhedrin with a Nasi to intercalate a year. The second is that there are certain reasons for ...
- 7,434
12
votes
Accepted
What is the א"ת ב"ש ג"ר calendar mnemonic?
The Shulchan Aruch 428:3 explains the mnemonic:
סימן לקביעת המועדים א"ת ב"ש ג"ר ד"ק ה"ץ ו"ף פירוש ביום א' של פסח יהיה לעולם ת"ב וסימן על מצות ומרורים יאכלוהו ביום ...
- 19.6k
11
votes
Accepted
Why some biblical holidays don't occur on certain days of the week?
The current fixed calendar is arranged (by adding or taking out an extra day in Marcheshvan or Kislev) such that Yom Kippur can't fall on Friday or Sunday (so there won't be two days in a row where no ...
- 97.4k
11
votes
Accepted
Why do Kisidran years only occur when starting on a Tuesday or non-leap Thursday?
Modular arithmetic time:
385 mod 7 = 0
384 mod 7 = 6
383 mod 7 = 5
355 mod 7 = 5
354 mod 7 = 4
353 mod 7 = 3
That's how far Rosh Hashana moves from year to year. The Kisidran options are 4 and 6. ...
- 97.4k
11
votes
Accepted
Date of the Akeida?
R. Yehuda Ayash points out that there are contradictory passages in the Zohar. In Parshat Vayikra it says that the Binding of Isaac took place on Rosh Hashanah, while in Parshat Vayeitzei it implies ...
- 49.1k
10
votes
Accepted
Where do we first see Cheshvan (as opposed to Marcheshvan)?
Midrash Abba Gurion to Ester (ed. Buber 3:7), which was redacted in the tenth century, refers to it as חשוון (Heshvan):
לתשרי זכות הרגלים, לחשוון זכות שרה
It is also found in Eisenbach's edition ...
- 35.4k
10
votes
Why was the calendar not arranged so that Yom Kippur never falls on Shabbat?
The fixed calendar already prevents Yom Kippur from falling on a Friday or Sunday, to avoid two consecutive days where all melachot are forbidden. (See Shulchan Aruch Orach Chaim 428:1 with e.g. Magen ...
- 41.8k
10
votes
Declare a leap year due to coronavirus?
The rabbis currently do not have the authority to declare a leap year because there is no Sanhedrin.
The current calendar was set up by Hillel II and is completely fixed by calculation. Indeed, even ...
- 42.9k
10
votes
Making my own Jewish calendar with paper and pencil
There's no need for a mashgiach since anyone can check on their own. Here's all you need to know to calculate any date.
In years whose value is 0,3,6,8,11,14,17 modulo 19 an extra month is added after ...
- 97.4k
8
votes
Is there a zero year in the ancient Jewish calendar?
Since the year begins at Rosh Hashanah, the number of the year changes then. Thus the year spans the secular year which changes in January. Thus this year (5776) started at Rosh Hashana 2015 and will ...
- 42.9k
8
votes
Accepted
What is the greatest number of holiday days falling on weekdays in a year?
Between Purim and the next Shemini Atzeret the calendar is completely fixed (no leap years, leap days, etc.). The four possibilities are:
Purim (F), Pesach (S-Sh), Shavuot (M), Tisha b'Av (S), Rosh ...
- 97.4k
8
votes
Accepted
Why are some dates off by one day?
I think I may have discovered the answer. After mulling over the problem for a bit, I realized that not all cycles are created equally. The 19-year cycle just determines which years are leap years; it'...
- 34.1k
8
votes
Accepted
Purim and Pesach in the same month
In 1999, the day of Purim fell out on the 2nd of March. This means that first few hours of pesach fell out on the 31st of March. Same happened in 1980, 1961....
The last time that Purim fell out on ...
- 3,849
8
votes
Accepted
What is the source for Hillel’s having included an expiration date in the calendar?
You write that:
It’s often said that when Hillel instituted the current calendar, he set an “expiration date” of 6000 AM; at that point the calendar would be invalid. Since Mashiach presumably will ...
- 41.8k
8
votes
Accepted
Tisha b Av calendar confusion
This year the ninth day of the month of Av fell on Shabbat. Since fasting on Shabbat is forbidden, the holiday of Tisha b'av (which literally translates as "the Ninth of Av", hence the confusion) was ...
- 5,020
8
votes
Why does the date for the prayer for rain change from one century to the next?
The rules try to keep the date for requesting rain in the late fall. They are not perfect. No rule would be except adding the ever-changing long decimal tropical year length.
If we were to take a ...
- 97.4k
8
votes
What did people say in Shemoneh Esrei and Kiddush of Shavuos when it didn't fall out on the 6th of Sivan?
Two basic answers exist to this question:
In reality, when the calendar was decided by testimony of the new moon, this phrase probably did not exist in the prayers. Maseches Sofrim 19:4 writes:
...
- 21.8k
8
votes
Accepted
Historical Daf Yomi calendar
I have found that Daf Yomi Calendar has the calendar for cycles 11 - 15.
This site does not have any earlier cycles.
I have found D.A.F.'s Talmud Tools which allows you to search back by Daf, Hebrew ...
- 42.9k
7
votes
Accepted
Why is there never a break between parshiot Parah and Hachodesh?
The Aruch Hashulchan in OC 685 says that there are no breaks between them because they are related to each other (unlike the others, which are unrelated to the ones next to them, meaning that Zachor ...
- 20.9k
7
votes
What did people say in Shemoneh Esrei and Kiddush of Shavuos when it didn't fall out on the 6th of Sivan?
Rav Yehoshua ibn Shu’ib, Rabbi Mordecai ben Abraham Benet, and the Mateh Moshe (Laws of Shavuot 690) explain that for this reason the more general word 'time' is used instead of the more precise 'day' ...
- 6,487
7
votes
Accepted
Which event is more infrequent?
tl;dr
Over a span of 689,472 years (the complete Hebrew calendar cycle), a three-Torah shabbat happens 465,929 times, and a two-Torah weekday happens 1,009,765 times.
For technical details, see below ...
- 41.8k
7
votes
Sources for Rav Saddia Goan on set days for Pesach
This opinion of R. Sa'adia Ga'on is quoted by R. Avraham b. Hiyya HaNasi. In his Sefer Ha-Ibbur, he writes (ma'amar sheni, sha'ar shemini):
ואמר הגאון ר' סעדיה בר' יוסף ראש הישיבה זצ"ל: קבוע היה ...
- 41.8k
7
votes
Accepted
Is the TorahCalc Molad Calculator accurate?
In short
It's their algorithm. It appears that they are using an inaccurate constant of 3.3 to back into the number of chalakim from the number of seconds. This constant should instead be 3 + (1/3). ...
- 38.5k
6
votes
Accepted
Parshat Ki Tisa on Shabbat Shekalim
This question is discussed in the Bavli (Megillah 30a) and while one opinion recommends reading from Shemot 30:17 to the end of the Parsha, and then reading Shekalim at the end, the conclusion is in ...
- 97.4k
6
votes
Accepted
Why do we start saying "Veten tal umatar" during Ma'ariv?
Actually, the sixtieth day after tekufat tishrei is currently December 5th or 6th - it hasn't been December 4th for about a hundred years. We say it on maariv of the day before, because that's when it ...
- 18.8k
6
votes
Mean Hebrew Year Length
The Jewish year varies in length, with an extra month some years and with some years having one more or one less day than usual. Ultimately, the main reason for the variation is to keep it from ...
- 47.8k
6
votes
Accepted
Mean Hebrew Year Length
A mean Hebrew month is 29 days + 12 hours + 793/1080 of an hour.
Back then they would add a 13th month into the year whenever the drift appeared to be getting too big, but not on a regular schedule, ...
- 97.4k
Only top scored, non community-wiki answers of a minimum length are eligible