Question: Why do we begin saying Tal U’matar on the evening of December 4 or 5? Why is the secular date relevant? Also, what should an American Jew do if he is in Eretz Yisrael (where people start saying Tal U’matar earlier) and then returns home before December 4 or 5?
Answer: My late uncle, HaRav Sholom Klass, zt”l, devoted an entire chapter of his Responsa of Modern Judaism (vol. 3) to your first question. We base our answer on his. Rabbi Abraham Rapoport of the London Beth Din also issued a pamphlet (No. 11, Nisan 5724) on this subject, which the late chief rabbi of England, Lord Immanuel Jakobovits, explains in great detail in his book, Jewish Law Faces Modern Problems. Let’s delve into the matter:
The Jewish calendar, though based primarily on the phases of the moon, is also dependent on the solar cycle in two distinct respects: 1) The various festivals must occur at certain seasons (e.g., Passover in the springtime). To insure that this requirement is met – and to align the Jewish lunar year (354 days) with the solar year (365 days) – seven leap months are added every 19 years. 2) Tal U’matar and the “Blessing of the Sun,” said every 28 years, is related to the seasons (December 4-5 and April 8, respectively).
The great Babylonian sage Samuel assumed the duration of the solar year to be exactly 365 days and six hours, with each season lasting 91 days and 7.5 hours (Eruvin 56a). But five generations later, R. Adda bar Ahava arrived at the much more precise figure of 365 days, 5 hours, 997 parts (one hour has 1,080 parts), and 48 moments (1 part has 76 moments) for the year – or 91 days, 7 hours, 519 parts, and 31 moments for the season (see the Perush commentary on Rambam, Hilchot Kiddush haChodesh, 10:1, quoting the Baraita [or Tekufa] deRav Adda).
R. Adda’s calculations have been accepted for determining the length of the average year in the Jewish calendar with reference to the festivals, while Samuel’s figure is used to this day for fixing the dates of Tal U’matar and the “Blessing of the Sun.”
Rabbi Jakobovits points out that R. Adda’s figure, though far more accurate than Samuel’s, corresponds somewhat less to the true astronomical value than the figure of the Gregorian Calendar introduced in 1582. The deviation of the latter is only one day in 3,600 years, while the present Jewish calendar, based on R. Adda’s figure, loses about 4.5 days every thousand years, so that we now celebrate Passover on average about eight days later than in 344 C.E., when Hillel II introduced the fixed calendar. A year is actually 365 days, 5 hours, 55 minutes, and 25.438 seconds long.
Our calculations for the Jewish month (i.e., from one molad to the next), however, is much more precise. It extends the true value by less than a second (29 days, 12 hours, 44 minutes and 3.5 seconds, against 29 days, 12 hours, 44 minutes and 2.841 seconds), so that our months still follow the phases of the moon quite accurately to this day.
The Gemara (Ta’anit 10a) says that in the Diaspora we commence praying for rain 60 days after the start of Tekufat Tishrei – the autumn season (the autumnal equinox). The Diaspora referred to in the Talmud is Babylonia; rain before that time in that area caused damage.
The Rosh (Ta’anit ad loc. 1:4) argues that we should act differently in places like Provence (in southeastern France) where rain is badly needed earlier lest the planted seeds be lost. The Korban Netanel (ad loc.) explains that birds and mice would eat the seeds, causing a great loss. The Rosh states that he heard (see Tur, Orach Chayim 117) Jews in Provence asking for rain earlier than the 7th of MarCheshvan (the starting point in Eretz Yisrael) and says this practice is correct.
The Mechaber (Orach Chayim, ad loc.) does not note any exceptions. All of Diaspora should start asking for rain at the same time. (See also the Taz [ad loc.], who states that we do not deviate from the Talmudic ruling recorded in Ta’anit 10a. We ask for rain on the 7th of MarCheshvan in Eretz Yisrael, and 60 days after the tekufah of Tishrei in the Diaspora.)
According to this view, the prayer for rain is unrelated to the climate and agricultural needs of particular localities. That would explain why we use Samuel’s simpler calculation for this prayer. It enables every Jew around the world to know the date for saying Tal U’matar without any complicated computations. Considerations of simplicity, though, do not apply to determining when various festivals etc. should be celebrated. For this purpose, we use R. Adda’s more accurate calculations.
According to the Julian Calendar (which corresponds to the calculations of Samuel), the tekufah of Tishrei (beginning of the fall season) always occurs on September 24 (Avudraham, quoted by Beit Yosef, Tur, Orach Chayim 117) so that Tal U’matar is said for the first time 60 days later, i.e., on November 21, at Ma’ariv (except in leap years when we say it on November 22).
These dates were fixed until Pope Gregory XIII introduced a calendar reform in 1582 and dropped 10 days from the calendar, declaring October 5 of that year to be October 15 and that every century year after divisible by four that not should not be counted as a leap year. Hence, in every century, the date for starting to say Tal U’matar is moved back one more day (in addition to the 10 it was moved back in 1582).
Thus, today, we begin saying Tal U’matar at Ma’ariv on December 4 or 5. In 2100, under our present calendar, we will begin saying it December 5 or 6.
(To be continued)