Outside of Israel, each of our three pilgrim festivals is observed for one day longer than the Torah prescribes. This extra day is tacked on to the beginning and end of Pesach and Sukkot, and Shavuot in the Diaspora is observed for two days, not one. This extra day is known as Yom Tov Sheni Shel Galuyot, or the second day of the festival for the diaspora.
When these festivals fall out in the middle of a week, that extra day creates a hardship for many of us who observe them and who may have businesses to run or jobs to go to. If the first day is a Thursday, that means that there are three sacred days in a row, Shabbat being the third day, which puts an added strain on those at home who must prepare for it.
Unless there was a good reason for keeping the extra day, this would seem to violate the principle of tirchah d’tzibbura, which roughly translates as unnecessarily burdening the community. (See, for example, the discussion in the Babylonian Talmud tractate B’rachot 12b.)
To be sure, Yom Tov Sheni Shel Galuyot was necessary in Second Temple times because messengers were required to announce the start of months to Diaspora communities, many of which were located far away, meaning that the messengers might not always get to each in time. That is no longer a concern, however, so why is there still a Yom Tov Sheni Shel Galuyot in our day?
Some background is called for. Our calendar is lunar/solar. We determine days by the sun and months by the moon. In the earliest biblical times, months were determined only by sighting the birth of a new moon — the molad. However, Leviticus 23:37 states, “These are the set times of the Lord, which you shall proclaim.” This verse clearly requires that the “set times” (meaning the festivals) must be proclaimed in some way, and it follows that the months in general must be as well.
In the late Second Temple period in the First Century B.C.E., that was the task of the Sanhedrin, the official legal body where Jewish law was concerned. It established the average length of the moon’s orbit (29 days, 12 hours, and 44.0115 minutes) and based on it, members of the Sanhedrin would go outside and look up to the sky in search of that barely visible crescent. This astronomical calculation was essential because if it was not known when to look for the molad, there would be no reason for the process to begin at all.
Because the moon might not be visible where they stood, reliable witnesses where required. They had to testify before the Sanhedrin that they, too, saw the “birth” of the new moon. If their testimony was considered credible, the signal was given for a torch to be lit and waved on the Mount of Olives.
The light of that torch would set off a chain of torchlightings, thereby communicating to the people throughout the Land of Israel and nearby Diaspora communities that a new month had been announced.
For those communities too far from the Land of Israel, messengers would be sent after the start of the previous month to relay the information.
Today, we know by the fraction of a second when the molad will occur over Jerusalem. One occurred there last Saturday, May 20, 2023, at 52 minutes and 46.62 seconds after 2 a.m., ushering in the month of Sivan 5783 at sundown later that day. Next year, Sivan 5784 will be preceded by the molad that will occur at 25 minutes and 29.97 seconds after 12 a.m. on Friday, June 7, 2024. Because we know this so precisely, Jewish calendars are available for years in advance. There thus would seem to be no need to observe that extra day.
Obviously, the moon does not get “reborn” every month. It does, however, come between the earth and the sun once every orbit, at which time it is initially invisible to us. As it begins its next orbit, a small crescent of light appears and the moon becomes visible. The average length as calculated by the Sanhedrin was the number used to determine when the molad was likely to occur.
As the Talmud testifies, in fact, this astronomical calculation was considered more reliable than eyewitness testimony. In BT Rosh Hashanah 24b-25a, a mishnah reports that witnesses testified before the Sanhedrin to seeing the new moon heralding the month of Elul. Rabban Gamliel II, the Sanhedrin’s president at the time, accepted their testimony and used it to declare when the following month, Tishrei, would begin, with its attendant observances.
Gamliel’s colleagues, however, rejected the testimony as false for what seems like valid reasons — reasons of which he could not have been unaware. The mishnah then reports that Gamliel also accepted the testimony of a second set of witnesses, which his colleagues also insisted was false (or more likely erroneous).
Presumably, Gamliel ignored the objections because he preferred to rely on his calculations in any case. According to his colleague Rabbi Yehonatan ben Uziel, however, Gamliel erred in making this calculation. At the very least, this dispute attests to the fact that calculations, rather than sightings, were not unusual as early as the late first century C.E.
Sometime in the second century, the sage Rabbi Meir reportedly argued for doing away with sightings altogether. That, at least, is what the fourth-century Babylonian sage Abba ben Joseph bar Chama, better known as Rava, claimed in BT Arachin 9b. (Rava, it should be noted, took the extra day to the extreme by observing two days for Yom Kippur. See BT Rosh Hashanah 21a.) Rava, therefore, attests to the possibility that sightings were done away with entirely in the second century.
Certainly, by the second half of third century C.E., calculations had more or less completely overtaken moon sightings in the Land of Israel. (See the Jerusalem Talmud tractate Sukkah 4:1 [54b].)
As several talmudic texts assert, those astronomical calculations were also used early on to create some sort of a fixed calendar, something that was of great benefit for those Diaspora communities that wanted to create their own authoritative calendars. In the mid-fourth century C.E., the sage Hillel II fine-tuned that calendar, and it soon became the standard for all Jewish communities to follow from then on, although it is not clear that every community adopted it in the near term.
Even before Hillel’s version, however, once a fixed calendar of sorts existed during the Sanhedrin’s days, the extra day ceased to be observed in most places outside the Land of Israel. (See BT Pesachim 51b-52a.) The Sanhedrin reinstituted it throughout the Diaspora, probably in its latter years (it ceased to exist early in the fifth century). It did so because of a fear that an “evil government,” in its words, might come along and issue edicts that would affect the proper observance of a festival.
For Maimonides, the Rambam, that action by our sages was decisive. Even though he acknowledged that “it would be appropriate according to law for [Jews] throughout the world to celebrate the holidays for one day alone” because a fixed calendar existed, the words of the sages should be heeded. (See his Mishneh Torah, the Laws of Sanctifying the Month, 5:4.)
Clearly, though, before the sages had that fear — which in fact was very valid in their day and beyond — they had ended the practice of adding on a second day. Today, we have no such fear anywhere. Not only has there been a fixed calendar since the mid-fourth century, but that calendar is readily available today for free in many supermarkets that cater to Jewish clientele. Thanks to modern technology, learning when new months will begin for any date well into the future and even when the sun will rise and set on those days are but a few keystrokes away. Shavuot in 2099 will begin at sundown on Sunday, May 24. Sunset in our area that day will be at 8:14 p.m. EDT (assuming daylight time still exists then).
That being said, to paraphrase Rambam, it is appropriate today, according to Jewish law, for Jews throughout the world to celebrate the holidays for one day alone.
There is a catch, however. Unless all streams of Judaism end the observance of the extra day, it could lead to even more sectarian conflicts within our communities. That was the concern in a discussion in BT Pesachim 51b-52a. In brief, if a person who no longer observed Yom Tov Sheni Shel Galuyot was visiting a community where it was still observed for whatever reason, that person could not publicly violate the sacredness of that day while in that community, in order to avoid creating conflict of any kind.
The Reform movement ended Yom Tov Sheni Shel Galuyot long ago. It is time for the leaders of the Conservative movement and those of the many Orthodox sects to consider doing the same, if for no other reason than that for many people it is a tirchah d’tzibbura, an unnecessary burden on the community.
Shammai Engelmayer is a rabbi-emeritus of Congregation Beth Israel of the Palisades and an adult education teacher in Bergen County. He is the author of eight books and the winner of 10 awards for his commentaries. His website is www.shammai.org.