Monday, December 18, 2006


Since tonight will be the fifth night of Chanukah, we wanted to enlighten you on a very interesting but technical discussion.

Kollel Iyun Hadaf


brought to you by
Kollel Iyun Hadaf of Yerushalayim
Rosh Kollel: Rabbi Mordecai Kornfeld

GENERAL : Fifth Night of Chanukah

Barry Epstein asked:

I heard a speech that the 5th day of Hanukah is the darkest day because it is the only day that can't fall on a Shabbos. The venue was a bris and therefore the point was that the bris brought light to this day. Since Hanukah doesn't have any rules regarding specific days, is this fact correct? If so, is it because of other Hagim that don't can't fall on certain days and therefore it leads the 5th day of Hanukah to always miss Shabbos?

Barry Epstein, Dallas, USA

The Kollel replies:

The fifth day of Chanukah is 29 Kislev. The rules for determining whether any calendar day can fall out on any particular weekday are as follows:
1) Every month of the year, except for three, has a set number of days. Three months can vary in length. Thus, the number of days in each month may be listed as follows:
Nisan - 30
Iyar - 29
Sivan - 30
Tamuz - 29
Av - 30
Elul - 29
Tishrei - 30
CHESHVAN - 29 or 30
KISLEV - 29 or 30
Teves - 29
Shevat - 30
ADAR - 29, and in a leap year the two Adars are 59 days

2) Regarding the variable months of Kislev and Teves, the rule is that there can be three combinations: Either both are 29 (the year is 'Chaser'), or both are 30 (the year is 'Malei'), or Cheshvan is 29 and Kislev is 30 (the year is 'k'Sidran', i.e. these two months follow the pattern of the rest of the months). The fourth possibility is not acceptable: Cheshvan cannot be longer than Kislev.

3) There are two rules to keep in mind regarding the day of the week that any calendar day falls out on:

a. We do not want Hoshana Raba to fall on Shabbos (because we won't be able to make the Hakafos with the Lulav).

b. We do not want Yom Kipur to fall on a Friday or Sunday (because if someone dies in the beginning of the first day, we will not be able to bury him until after the end of the second day).

In other words, Hoshana Raba (21 Tishrei) cannot be a Shabbos, Tuesday, or Thursday, and Rosh Hashanah cannot be on a Sunday, Wednesday or Friday. This is known as "Lo AD'U Rosh" (see Rosh
Hashanah 20a, Rambam Hilchos Kidush ha'Chodesh 7:1,7, Ra'avad there 7:7).

4) Based on these rules, our friend Reb Yoel ha'Levi Steinberg pointed out the following:

a. If Cheshvan is 29 days, then a simple look at the calendar will show that 29 Kislev cannot fall on a Shabbos without making the previous Yom Kipur a Friday, which is not allowed (see above, #3b).

b. If Cheshvan is 30 days, then Kislev must be 30 days as well (see above, #2). If the year is not a leap year, then a simple look at the calendar will show that 29 Kislev cannot fall on a Shabbos without making the following Hoshana Raba a Shabbos, which is also not allowed (see above, #3b).

c. However, if Cheshvan and Kislev are both 30 days and the year is a leap year, then it would seem that we do not have to violate any of the rules in #3. Why, then, can't 29 Kislev be a Shabbos when both Cheshvan and Kislev are 30 days, and it is a leap year? (Reb Yoel did not provide an answer to this point.)

5) To answer this, let's go back to Rosh Hashanah. If Cheshvan is 30 days and the 29th of Kislev is a Shabbos, that means that the Rosh Hashanah of that year was a Tuesday. When Rosh Hashanah is Tuesday and the year is a leap year, the Rambam writes (Hilchos Kidush ha'Chodesh 8:10) that the year must be k'Sidran, and not Malei (i.e. Cheshvan will only have 29 days). Thus, 29 Kislev will not be Shabbos.

The explanation for this is not perfectly clear; here is what I saw:

When Rosh Hashnah is Tuesday and the year is a leap year, on what day will the following Rosh Hashanah fall out?

If the year is 'k'Sidran' (Cheshvan 29, Kislev 30), the next Rosh Hashanah will be on Monday. If the year is 'Malei' (Cheshvan 30, Kislev 30 - the scenario we are looking for) next Rosh Hashanah will be on Tuesday. Both cases do not violate the "Lo AD'U Rosh" rule (see above, #3). Since we have an acceptable scenario for the year if it is 'k'Sidran' (i.e. the months of Cheshvan Kislev follow the normal 29/30 day pattern that the other months follow), we will not make the year 'Malei'. Thus, in a leap year when Rosh Hashanah was Tuesday, Cheshvan is assigned only 29 days, and the 29th of Kislev will be
Friday and not Shabbos (see above, #4a). [Based on KI HI CHOCHMASCHEM by Rav Shlomo Rosner, p. 133]


There is a more complicated explanation for the why the leap year under discussion must be k'Sidran, but it is beyond the scope of our discussion. Here is a rough outline of how it works:

Rosh Hashanah will be on Tuesday in a leap year only if the Molad was between 12:00 PM Monday and 11:59:59 AM on Tuesday. When we add to that thirteen times the length of the lunar month, we find that the Molad of the following Rosh Hashanah will be sometime between Sunday morning and Monday morning. THe appropriate day for the following Rosh Hashanah is therefore Monday (since Rosh Hashanah cannot be a Sunday; see above #3). If the year is "Malei", it will push off Rosh Hashanah to Tuesday, which is unnecessary and undesired, therefore the year will be k'Sidran. (Based on Peirush printed in the Rambam, Hilchos Kidush ha'Chodesh 8:10, see Itim l'Binah by R. Yosef Ginzburg, end of Ma'amar #11.)

I hope this was helpful.

Best wishes,
Mordecai Kornfeld


Rabbi Seinfeld said...

Not only is the 5th day the darkest day of Hannukah, it's the darkest day of the year. This is because it is always the day before the new moon closest to the winter solstice. So even if it's not the solstice itself, it will be the darkest day of the year. How appropriate that Channukah straddles this day and that the mitzvah in that darkness is to light a single candle. See this entry

Thanks for a very interesting post.

Anonymous said...

b. We do not want Yom Kipur to fall on a Friday or Sunday (because if someone dies in the beginning of the first day, we will not be able to bury him until after the end of the second day).

Kivod HaRav-
HUH? Y"K is one day only.
Please clarify.

Anonymous said...

I think he meant Rosh Hashanah

Anonymous said...

becaus of Shabbos, there will be two days

Anonymous said...

some families have a minhag to give chanukah Gelt on the 5th day. The only reason I was able to find was, I believe it is from the Shelah Hakadosh being that the 5th day is the only day that can't fall out on Shabbos.