A number of readers had questions concerning the calendar and the calculations concerning when we start asking for rain.

Both H. Eaglefeld and AJ Roth pointed out that were one to count 60 days after the autumn equinox, the date one would arrive at is approximately November 20, not December 5 or 6. Since that is the case, why do we begin asking for rain in December instead of 60 days after the equinox, as the Gemora says that we should?

(As I wrote in a previous post, in order to try and simplify a complicated topic, there may be inaccuracies, and hopefully only minor ones, in the explanation. I apologize for this, and appreciate any insights that you may have.)

In order to explain the reason for this discrepancy, a little more information about the calendar is needed. In the Halachic writings, we find two methods of calculation used to portion the year into seasons. One is called Tekufa D'Shmuel (The Tekufa calculation of Shmuel) and the other is referred to as Tekufa D'Rav Adda. When implementing these calculations, one will find that using the Tekufa calculation of Rav Adda will result in a more astronomically precise calculation than using the Tekufa calculation of Shmuel.

We are very familiar with the Tekufa calculation of Shmuel. That is the calculation that is still used in the present secular calendar, the Gregorian calendar. This calculation was used as well in what is referred to as the Julian calendar. In fact, it is this calculation that resulted in the switch from the Julian to the Gregorian calendar. Because this calculation was not an exact one, the calendar dates slowly lost their alignment with what astronomically should have been the calendar date. That is why Pope Gregory changed the calendar (in 1582) by skipping a number of days (October 5 - 14) thereby putting the calendar date where it should have been. With this change plus the system of leap years that the Gregorian calendar uses, the calendar stays on track. (A historical note: The United States and England did not change calendars until 1752, when the dates September 4-14 were eliminated.)

However, as far as the Jewish nation using the Tekufa calculation of Shmuel goes, no "rectification" was ever implemented to make the calendar dates astronomically aligned. Therefore, over time, the date that we calculate as Tekufas Tishrei, or the autumn equinox, actually moved away from the date of the true astronomical autumn equinox. This factor, added with the date change the implementation of the Gregorian calendar brought with it, explains why the date of the 60th day after the actual equinox is not the day we call the 60th day after the equinox. Hence, our Tekufas Tishrei is not the true astronomical date of the autumn equinox.

Why do we use this method of calculation which results in am imprecise result, a result that is astronomically incorrect? R' Moshe Feinsten zt"l (Igros Moshe Orech Chayim 4:17) writes that Shmuel most definitely did not err in his calculation. He knew that his calculation was not perfect. However his calculation was one that is easily understood and implementable by the layman. For this reason, we use this calculation for determining when to start asking for rain. The date that we start asking for rain has no significance itself. It merely marks that time when rain is needed. Therefore, if we start asking for rain a number of days later, there is no great loss, as we are still asking for rain when it is needed. For matters in which the astronomical alignment of the date carries with it greater significance, the calculation of Rav Adda, a more complex and precise calculation, is used. ------

Another clarification: The reason why the date for adding the request in the land of Israel is the 7th of Cheshvan has to do with how long it took for a pilgrim leaving Jerusalem to return home. There are various explanations for this calculation. The Mishna which mentions this date says that the time period given is how long the journey to the Euphrates River area from Jerusalem took, which is the farthest distance from which anyone would have come. Some say that this time period is how long it took the slowest pilgrims to complete the journey. There are others who say that in reality, this journey on the average took more than the allotted amount of time. However, because we do not want to further delay the request for rain, we start the request at the time one could reach this destination if one traveled during both the day and night. -----

One last clarification: When we start asking for rain, we are asking for rain in the "country" in which we live. It is for this reason that commentators such as Rabbeinu Asher find that logic is lacking behind why all of the Diaspora follows the date that rain was needed in Bavel. In some places in the world, rain is needed a full six months later, not in December. However, as we mentioned in the last post, we follow the Bavel oriented date because we have a tradition to do such. We can keep in mind