Bein HaShemashos
As explained at length by the Mishnah Berurah and Beiur Halachah, there are two basic views held by the Rishonim as to the time period known as bein ha-shemashos – twilight: The first view, known as the view of R. Tam and followed by Shulchan Aruch,[1] holds that bein ha-shemashos begins approximately 58 minutes after sunset and it lasts for approximately 14 minutes, when tzeis ha-kochavim takes place – 72 minutes after sunset. According to this view, Shabbos does not begin on Friday evening for almost an hour after sunset. The second view, known as the view of the Geonim and followed by the Vilna Gaon, holds that bein ha-shemashos begins right at sunset, and can last as briefly as 14 minutes, or much longer, depending on the season of the year and the exact geographic location. The further north one is from the Equator, the longer it takes for three stars to appear after sunset. According to this view, all Shabbos restrictions begin exactly at sunset, since once bein hashemashos arrives, it may very well be Shabbos.[2]
According to the Mishnah Berurah, this dispute remains unresolved and one must accept the stringencies of both views. That means that on Friday evening one must desist from all weekday activities yet before sunset,[3] while on Saturday night, Shabbos is not over until 72 minutes after sunset. This ruling was followed by many communities in Europe until WW II,[4] and it is still followed by most communities today worldwide.
But we find other opinions as well. In Eretz Yisrael, most communities have adopted the second view as the basic Halachah. Accordingly, they are extremely careful on Friday to cease all work well before sunset, but they are lenient as far as Motzaei Shabbos is concerned. Since, in Eretz Yisrael, three stars appear fairly quickly after sunset, Shabbos is over anywhere from 25 to 45 minutes after sunset, depending on the various opinions and customs.[5] Only a small number of communities are stringent and wait 72 minutes after sunset for Shabbos to end.[6]
In the United States, where it takes much longer than in Eretz Yisrael for three stars to appear, Igros Moshe rules that Shabbos is not over until at least 50 minutes have passed from sunset. But according to his opinion, even R. Tam would agree that one need not wait more than 50 minutes in the geography of the U.S. “since at that time it is already just as dark as it was after 72 minutes in Europe.” While Igros Moshe strongly recommends that a ben Torah and a G-d fearing person wait 72 minutes after sunset for Shabbos to end as was the custom in Europe, he rules that one is not required to do so according to the basic Halachah.[7]
[1] This is the opinion of Shulchan Aruch in our chapter. In Y.D. 266:9, it appears as if Shulchan Aruch rules in accordance with the second view.
[2] In addition to these prominent schools of thought, there is a third view, held by the Yereim, that bein ha-shemashos begins 14 minutes before sunset.
[3] As Mishnah Berurah notes earlier, it is appropriate to begin Shabbos as early as 20-30 minutes before sunset.
[4] While this was the rule in prewar Europe, there were exceptions as well. Some communities, notably Chassidic communities in Poland and Hungary, followed R. Tam’s view even on erev Shabbos and did not begin Shabbos until well after sunset. There were also communities who were stringent regarding Motzaei Shabbos and did not end Shabbos until 96 minutes after sunset, based on the opinion quoted in Sha’ar ha-Tziyun 21 that 4 milin is 96 minutes.
[5] According to long-standing custom in Yerushalayim, one can consider it night with regard to issues of Rabbinic law (such as davening Ma’ariv, provided that one repeats Kerias Shema later) as early as 20 or even 17 minutes after sunset (see Halichos Shelomo, vol. 1 pg. 164-165, for a full perspective on the various times cited).
[6] See Ketzos ha-Shulchan 93:1 (Badei ha-Shulchan 2).
[7] See Igros Moshe, Y.D. 2:79; O.C. 4:62. Some communities in the U.S. wait as little as 42 minutes after sunset for Shabbos to be over; see Sha’arei Zemanim, pgs. 87- 92 for an explanation of this custom.