When Does Shabbat End?
There are a number of different positions regarding how much time after sunset on Shabbat day does Shabbat end.
- 1 Introduction
- 2 Emergence of the Stars (Rav Tukachinsky)
- 3 Four Mil (Rabbeinu Tam)
- 4 Three Quarter Mil (Gra)
- 5 Halacha
- 6 Asking Someone Else to Do Melacha
- 7 Sources
The Talmud has several different statements about when the nighttime begins for all purposes including when Shabbat ends. The clearest statement on the matter is that of Shmuel in Gemara Shabbat 35b; once three medium stars are visible in the sky it is considered night. This time period is called Tzeit Hakochavim, the emergence of the stars. Though, there are multiple Gemaras that comment on the time span between sunset and Tzeit HaKochavim. The Gemara Shabbat 34b records the opinion of Rabbi Yehuda that night only begins after a period of twilight which elapses from shekiya (sunset) for another two thirds of a mil or three quarters of a mil. Additionally, Rabbi Yosi disagrees and thinks twilight is minimal, literally "the length of time it takes to bat an eyelash", though not precisely that amount of time. Finally, the Gemara Pesachim 94a indicates that nightfall doesn't begin until 4 mil after shekiya. There are three main approaches in the rishonim and achronim as how to resolve these statements of the Talmud in a cohesive manner.
Rabbenu Tam's Answer
Rabbenu Tam held that there are two shekiya's; the first is astronomical sunset and afterwards it is nighttime for korbanot purposes, but otherwise it is still day until the second shekiya, which occurs three and a quarter mil after sunset. Then there is a duration of twilight of Rabbi Yehuda that is at most three quarters of a mil. For all purposes besides korbanot nighttime begins four mil after shekiya. This is also the understanding of most rishonim and Shulchan Aruch. This method would not allow relying on the emergence of stars method because the stars under discussion are subject to interpretation. Those who rely upon that are described below. Rabbenu Tam's approach is subject to further debate as how to understand the time of four mil, whether it is measured in fixed minutes, seasonal minutes (shaot zmaniyot), or astronomical degrees.
Vilna Goan's Answer
The Vilna Goan (Gra) explained that the Gemara Pesachim 94a was merely describing a time of night for when travelers could no longer travel. However, for halachic purposes nightfall begins after the twilight, which is three quarters mil. Similarly, this interpretation is subject to further debate as how to understand the time of four mil, whether it is measured in seasonal minutes (shaot zmaniyot) or astronomical degrees. No one who accepts the opinion of the Gra assumes that it is fixed minutes.
Rav Tukachinsky's Approach
Rabbi Yechiel Michel Tukachinsky disagreed with the earlier approaches that used either time based methods of four mil or three quarter mil. With respect to the Gemara Pesachim he accepted the Vilna Goan's argument that it wasn't relevant to the determination of halachic night. Also, he understood that really Rabbi Yosi's twilight starts slightly later than that of Rabbi Yehuda's twilight. The only method that a person could use to calculate when night begins is the emergence of three stars. To literally look up at the stars and decide when Shabbat is over could only be applied practically by someone who is an expert in this area as there are many preconditions to using this method and their determinations are complex. These include: the stars need to be in close proximity and not spread out, they need to be small stars, the three stars can only be relied upon if the Western part of the sky has darkened to the point that the area right above the horizon is as dark as the area far above the horizon. Nonetheless, only an The best way to apply this opinion is to take the determination of when stars are visible by an expert and then extrapolate based on degrees below horizon to the rest of the world.
Emergence of the Stars (Rav Tukachinsky)
According to this position, anything that is stipulated in the Gemara (see below) about the amount of time between sunset and Tzeit HaKochavim is only applicable to Bavel (Babylonia) and Israel during the Tishrei and Nissan equinoxes, not for the rest of the world nor during any other time of the year. The astronomical method uses the time that it takes to see the three small stars in Israel and the position of the sun at this time to extrapolate a calculation for when Shabbat should end for the rest of the world. In Jerusalem, during the Tishrei and Nissan equinoxes, it takes approximately 32 minutes in the winter and 38 minutes in the summer (in the United States and Europe, 50-60 minutes) after sunset to see these three stars in the sky. At this time, the sun has set 8.5 degrees below the horizon. Therefore, Shabbat ends when the sun has set 8.5 degrees below the horizon in every other location in the world at any other time during the year 
Four Mil (Rabbeinu Tam)
The Astronomical Method (As Degrees)
Based on the Gemara's above there are a number of Rishonim that try to reconcile the different statements, the most notable of the opinions being that of Rabbeinu Tam who concludes that there is not one but two sunsets that halacha recognizes. The first of them is the natural sunset, which marks the beginning of the sun's setting. Then, 3.25 mil later, a second, halachic, sunset occurs, lasting for 0.75 mil, after which is Tzeit HaKochavim. The first 3.25 mil, for halachic purposes, is completely considered halachic day as there is still some daylight in the sky, while the final 0.75 mil is ambiguous as to whether is considered halachic day or night (Bein HaShemashot) since the light is diminished. The Gemara in Pesachim is referring to the time between the first sunset and Tzeit HaKochavim and the Gemara in Shabbat is referring to the time between the second sunset and Tzeit HaKochavim.
For those who follow Rabbeinu Tam's position, Tzeit HaKochavim and the end of Shabbat occur at a uniform 4 mil after natural sunset for all locales. The only difference among the different interpretations of Rabbeinu Tam's position is how long to define a mil, which has ramifications for how long 4 mil would be and when Shabbat would end.
Those who accept Rabbeinu Tam's position include at least 25 rishonim: Tosfot (Pesachim 94a s.v. Rabbi Yehuda, Shabbat 35a s.v. Trei, and Zevachim 56a s.v. minayin), Ramban (Torat Haadam Avelut Yeshana n. 105 s.v. vrayiti), Maggid Mishna (Shabbat 5:4), Ran (on Rif Shabbat 15a), Sefer Hatrumah (Hilchot Tefillin), Rav Chaim Ben Yakov of London (compiled 1287, printed by Mosad Rav Kook in 1962, Shabbat ch. 2 p. 207), and Shulchan Aruch O.C. 261:2. Yabia Omer OC 2:21:1-3 also cites that this is the position of the Ran Yoma 81b, Ritva Shabbat 35a, Meiri Shabbat 35a, Smag Asin 32, Roke'ach 51, Mordechai Shabbat 35a, Rashba Brachot 2b, Orchot Chaim Yom Kippurim n. 3 citing Rav Hai Goan, Baal Hameor Brachot beginning and Arvei Pesachim s.v. Rav Chinana, Raah on Brachot 27a, Ohel Moed Shabbat 2:7, Rabbenu Peretz on Smak 96, Rosh Tanit 1:12, Rosh Yoma 8:8, and Tosfot Harosh Brachot 2b. In Chazon Ovadia Shabbat v. 1 p. 269 he adds the Raavad, Raavan respona 2, and Rabbenu Yerucham. Dor Hamelaktim v. 1 p. 412 writes that Tosfot Rid (Mehudra Telita Shababt 34b), Nemukei Yosef Shabbat 34b, Hashlama Shabbat 34b, Maharil 163, and Maharik 173 concur with Rabbeinu Tam.
Many poskim hold this as well including: Dor Hamelaktim v. 1 p. 412 cites the Radvaz 1352, Rama (Darkei Moshe Haaruch 261:1), Prisha 261:4, Bach responsa 154, Magen Avraham 331:2, Tosefet Shabbat 261:11, 331:10, and Chatom Sofer OC 80. He concludes with a citation of the Kuntres Ben Hashemashot by R' Shemerler that lists 183 rishonim and achronim who follow Rabbenu Tam!
- Others interpret Rabbeinu Tam slightly differently and state that Tzeit HaKochavim occurs not 72 natural minutes but 72 halachic minutes (1.2 halachic hours per Sha'ot Zemaniot) after natural sunset. 
- The most standard of these positions is that a mil is 18 minutes. Therefore, there are individuals and communities who end Shabbat only after 72 fixed minutes after natural sunset.
Interpretations and Derivatives of Rabbeinu Tam's Position
- There are those fundamentally agree with Rabbeinu Tam's 4 mil opinion, but define a mil as more than 18 minutes. Some define a mil as 22.5 minutes, making Tzeit HaKochavim 90 minutes after sunset. Others define a mil as 24 minutes, making Shabbat end 96 minutes after sunset. Finally, some of those of who hold of a 24 minute mil maintain Tzeit HaKochavim occurs two hours after sunset.
Answering the Questions for Rabbeinu Tam
- Some say that Rabbeinu Tam was only relevant in France but he would agree that in Israel or in place closer to the equator night begins much before 4 mil. In essence Rabbeinu Tam would agree with the Gra. However, others think this is untenable.
- Some say that Rabbeinu Tam held that it is necessary to see 3 stars on the lower part of the Western sky which aren't seen for much longer than most other stars. Others disagree.
Three Quarter Mil (Gra)
According to Degrees
The other major position that sought to resolve the contradiction in Gemaras was that of the Geonim and the Vilna Gaon (Gr"a) who held that there is only one halachic sunset, which occurs at natural sunset. The 0.75 mil the Gemara was referring to is the time that it takes 3 medium sized stars to appear in the sky, which is nighttime on a Torah level. We are then required to wait longer until 3 small stars appear to appear to end Shabbat. When the Gemara was speaking about 4 mil, it is referring to when all the stars appear in the sky, which does not have halachic significance. This position maintains that Tzeit HaKochavim occurs after 0.75 mil after sunset, long before the 4 mil presented by Rabbeinu Tam.
Many Rishonim and Geonim agree with the opinion of the Vilna Goan including the Ri and Rambam. Many achronim and poskim hold of this approach. Many contemporary poskim state and confirm that the minhag is like the Gra.
The application of the Gra's opinion of 3/4 mil practically is generally understood to be done by degrees below horizon. The reason for this opinion is that it would account for the difference in the places of the world and standardize how dark it is to be considered nighttime. This is the approach of myzmanim, Rav Tukachinsky, Rav Schachter, and Rav Belksy.
- Many shuls have the custom to wait 40-42 minutes after sunset to end Shabbat.
- Rav Moshe Feinstein held that Shabbat ends at a maximum of 50 minutes after sunset as by then, the stars that will usually appear in the night sky are out by then.
- There are poskim that made pesakim for the land of Israel specifically. The more lenient positions held that Shabbat ends 24 minutes after sunset in the winter and 30 in the summer in Israel. Those who were more stringent held that Shabbat should end 45-50 minutes after sunset in Israel.
- Rav Yosef Dov HaLevi Soloveitchik (1903-1993) held that Shabbat ends 30 minutes after sunset for New York and Boston, though he privately would wait longer. 
- In Baghdad, the practice of the Ben Ish Chai was to keep Shabbat until 27 minutes after sunset.
- Using the 40 minutes even for a summer day in Jerusalem, that is equivalent to 8.085 degrees below horizon, which would yield 48 minutes on a equinox day in Amsterdam (where the Minchat Cohen lived) and 72 minutes in the summer for Warsaw. He notes that the Minchat Cohen (2:5) advocated for Rabbeinu Tam but upon investigation came to the conclusion that the method of stars emerging occurred at 48 minutes.
For an equinox day here's a timetable of Tzet Hakochavim times according to degrees based on MyZmanim.com and Sefer Zmanim Khalacha.
|Degrees below Horizon||Minutes after Sunset in Yerushalayim (32°N)||Minutes after Sunset in NY (41°N)|
Using Rabbenu Tam for a Safek
- Some hold that we follow the Gra and one should not use the opinion of Rabbenu Tam even as a safek or as a factor in any case. However, others disagree and consider Rabbenu Tam to be a valid opinion even though it isn't the one that is accepted in practice and therefore it can be used as a factor in halacha.
Asking Someone Else to Do Melacha
- According to Sephardim, it is permitted for someone who keeps Rabbenu Tam time to ask someone who doesn't keep Rabbenu Tam time to do Melacha for him.
- Shaar Hatziyun 293:3 writes that it is the time it takes to walk 49 amot which is approximately half a minute. (It is dependent on the amount of time of a mil which is the time it takes to walk 2000 amot.)
- Tosfot Pesachim 94a s.v. Rabbi Yehuda, Tosafot on Shabbat 35a, Sefer HaYashar 221)
- The Bei'ur Halacha (293:1 s.v. ad cites the Minchat Cohen who is of the opinion that even Rabbeinu Tam, who holds that Shabbat should end 72 minutes after sunset (the time it takes to walk 4 mil), would concede that if three small stars in close proximity to each other are visible, Shabbat is over even if 72 minutes have not yet elapsed. This is in contrast to Rav Ovadia Yosef (Shu"t Yabia Omer 2:21) and the Orot HaChaim's opinion that Rabbeinu Tam and Shulchan Aruch are really stating the same position. The Orot HaChaim explains that the stars being mentioned in the Shulchan Aruch are ones that are closer to the western horizon where the sun sets, which apparently take longer to become visible.
- Biur Halacha 261:2 s.v. sh'hu citing the Pri Megadim
- Biur Halacha 261:2 s.v. sh'hu citing Minchat Cohen and Biur Halacha concurs.
- Biur HaGra OC 261:12
- Gra 261:12 at the beginning notes that all of the times in the Gemara are all according to the sun appears on the horizon in Bavel and it would need to be extrapolated to the rest of the world. Biur Halacha 261:2 s.v. sh'hu in citing the Gra, Magen Avraham, and Minchat Cohen clearly and explicitly interprets that the Gra would voche for shaot zmaniyot, seasonal minutes. However, based on Rabbi Belsky myzmanim.com ("Degrees" accessed August 5 2020) there is another approach that calculates the times for the Vilna Goan based on degrees below horizon. As opposed to shaot zmaniyot which takes into account the season or the year, degrees below horizon takes into account the latitude of location in question, though not the longitude or season of the year. This is also the view of Rav Hershel Schachter (Halachos Associated with Zmanim, min 72-74) and Rabbi Levy in Zmanim Bhalacha.
- Zmanim KHalacha p. 43 quotes Hacham Ovadia as holding that the minutes for Alot HaShachar do not depend on location but rather shaot zmaniyot. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Peirush HaMishnah to Berachot (1:1), Rambam uses a unique Arabic term when referring to Alot HaShachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light in the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating Alot HaShachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that Alot HaShachar's calculation is determined by degrees below the horizon.
- Ben Hashemashot 2:8 p. 29
- Tosfot Shabbat 35b s.v. elah’s asks why Shmuel needed to state that the halacha follows Rabbi Yosi with respect to the kohanim not being able to eat trumah if the only discrepancy between Rabbi Yehuda and Rabbi Yosi is minimal, the bat of an eye. Tosfot answers that in fact Rabbi Yosi’s Ben Hashemashot doesn’t begin immediately after Rabbi Yehuda’s, it only begins a little bit or much later. Gra OC 261:12 at the end argues that the Gemara Shabbat 35a is pretty clear that in fact Rabbi Yosi’s Ben Hashemashot starts immediately after that of Rabbi Yehuda’s. Rather the answer to Tosfot’s question is that kohanim can eat Trumah during Ben Hashemashot, however, since we follow Rabbi Yosi they can’t eat until after Rabbi Yehuda’s Ben Hashemashot. Rabbi Yechiel Michel Tukachinsky in Sefer Ben Hashemashot 2:8 notes that the Gra’s opinion is against almost all the rishonim and our text of the Gemara, which the Gra needed to emend. Accordingly he rejects the conclusion of the Gra and sides with Tosfot and others that the Ben Hashemashot of Rabbi Yosi is not immediately after that of Rabbi Yehuda’s. In fact it starts a while later. Therefore, he holds that nighttime begins with the emergence of three stars and is irrelevant to the Ben Hashemashot of 3/4 mil elapsing.
- Biur Halacha 293:2 s.v. shiyru concludes that someone who isn't an expert in the matter of determining when the sky is equally dark on the Western side and that it isn't a cloudy day in order to then check when three stars emerge should not rely on this method. Furthermore, in Biur Halacha 261:2 s.v. sh'hu writes that only on the days when it is very long to follow the 4 mil of Rabbenu Tam according to shaot zmaniyot then one can rely upon the method looking at the stars with all of its conditions. Nonetheless, in Biur Halacha 293:2 s.v. ad he directly asks the question as to why Shulchan Aruch cites both the opinion of Rabbenu Tam that one must wait four mil and also the emergence of the stars method from the gemara. He first answers that if someone doesn't know when four mil elapses such as if he doesn't have a watch then he can use the stars method, however, if he knows he must wait four mil even after the stars emerged. Alternatively, he cites the Minchat Cohen who says that even Rabbenu Tam would allow breaking Shabbat after the emergence of stars if that were to happen before four mil. Biur Halacha ends by saying that even the Minchat Cohen would concede that it is proper to wait for the Gra's condition that the Western part of the sky be darkened equally since it is within 4 mil. Besides this statement he does not give any statement whether one should rely on the Minchat Cohen. (See Dirshu 293:9 who quotes the Biur Halacha 261:2 s.v. sh'hu to be suggesting always to wait for four mil initially and not rely on the stars method. However, from seeing the language of that Biur Halacha as well as the one in 293:2 s.v. ad their interpretation seems questionable.)
- Shulchan Aruch Orach Chaim 293:2 based on Ran and Yerushalmi
- Shulchan Aruch Orach Chaim 293:2. Mishna Brurah 293:3 explains that although in theory three medium stars suffices but since no one today is enough of an expert to make such a determination we need to use three small stars. Mishna Brurah 293:4 cites the Tiferet Yisrael Shabbat ch. 2 that in addition to three small stars one needs to see three medium stars, however the Mishna Brurah proceeds to challenges this. He concludes that if one follows the Gra in Likutim that the sky needs to be dark to the point that the entire Western side is equally dark and not red at all then one need not be concerned for the Tiferet Yisrael.
- Mishna Brurah 293:4 citing the Gra in Likutim, Biur Halacha 293:2 s.v. ad, Biur Halacha 261:2 s.v. sh'hu
- Shu"t Igrot Moshe, Orach Chaim 4:62
- Rabbi Yechiel Michel Tukachinsky, Sefer Bein HaShemashot. Berur Halacha (Zilber) Tinyana Siman.
- In the New York area, this usually takes approximately 40 minutes after sunset at the equinox, and as much as 51 minutes during the summer.
- Under the 18 minute definition of a mil, this would consider halachic day to last until 58.5 minutes after natural sunset. Because of this, Chassidic communities that held like Rabbeinu Tam in Europe continued to do melacha even after natural sunset on Friday evening in America, because, for them, Shabbat had not started yet. Such a practice was contrary to the practice of the rest of the Orthodox community in America, as everyone else stopped doing melacha at natural sunset. Upon the controversy that ensued, Rav Aharon Kotler forged an agreement with these communities that they would begin Shabbat with everyone else at natural sunset.
- Teshuvot V'Hanhagot 1:268
- 72 mins/(60 mins/hr) = 1.2 halachic hours.
To determine how much time this is in natural time, divide the total number of minutes of sunlight that occurred that day (dawn to sunset) by 12, yielding the amount of minutes in an halachic hour on that particular day. Multiply the solution by 1.2 to determine how many minutes after natural sunset Shabbat should end.
- This was the custom of Minsk, based on a letter from the Chofetz Chaim (Dated winter 1916) copied in the Sefer Birur Halacha Tinyana p. 95, as well as the position of Rav Ovadia Yosef (Yalkut Yosef 293:3, Zmanim K'Halacha, page 43).
- Based on Shulchan Aruch, Orach Chaim Siman 459:2. Dor Hamelaktim Shabbat v. 1 261:2:2 p. 409 organizes the three approaches to the amount of time a mil takes. The first approach holds 18 minutes. Those who hold this include Shulchan Aruch Y.D. 69:6, O.C. 459:2, Rama O.C. 261:1, Shach YD 69:25, and Halichot Olam v. 6 p. 7. The second approach holds it is 24 minutes. Those who hold this include the Pri Chadash YD 69:26, OC 459. Kitzur Shulchan Aruch 36:11 and Chayei Adam 30:9 mention it as one opinion. The third approach is 22.5 minutes. Those who hold that include the Chok Yakov 459:10. See Mishna Brurah 459:15 who follows that approach but in other places he follows 18 minutes including 92:3, 184:20, and 235:4.
- 18 min/mil x 4 mil = 72 mins. Biur Halacha 261:2 s.v. sh'hu advocates for the position of the Minchat Cohen to follow shaot zmaniyot, seasonal minutes, for the opinion of Rabbeinu Tam, as opposed to the Pri Megadim who held it was 72 fixed minutes. Yet, in a letter the Chofetz Chaim (Dated winter 1916 and copied in Sefer Birur Halacha Tinyana p. 95) wrote that the minhag of Klal Yisrael is only to wait 72 fixed minutes. Aruch Hashulchan 293:1 also writes that the minhag is to keep 72 fixed minutes. Rabbi Meir Mazuz (Bayit Neeman 1:28) writes that we're strict for Rabbenu Tam but only for 72 fixed minutes and the source for observing Rabbenu Tam with shaot zmaniyot is based on a mistake.
This was the position advocated by R' Moshe Feinstein for Bnei Torah (even though he said 50 minutes was sufficient).
- 96 minutes- Satmar Rebbe (Zemirot Divrei Yoel) and Shu"t Beit Avi (3:117)
- Uvdot V'Hanhagot L'Beit Brisk (Vol. 4, page 54) in the name of the Brisker Rav. This position is based on the Rambam's position that a mil is 24 minutes and on those who maintain there are not four but five mil for Tzeit HaKochavim.
24 mins/mil * 5 mil= 120 mins
- Rav Masas in Tevuot Shemesh YD 1:92 s.v. vod writes that Rabbeinu Tam would agree in Israel because his position contradicts the reality in those places. Rav Mazuz in Bayit Neeman 1:25 s.v. umistabra writes that Rabbeinu Tam would agree with the Gra had he lived in Israel. Essentially they both agree if you see the stars Shabbat is over. The only reason he said his opinion was because he had a contradiction between the two gemara's and his answer fit with the reality he observed. The reason that the Shulchan Aruch and Pri Chadash who lived in Israel and Egypt accepted Rabbeinu Tam was because they didn't have clocks to accurately check 4 mil and also there was no better answer to the contradiction in gemara's. Rav Yosef Schwartz (Divrei Yosef 43b) and Rav Chaim Avraham Gagin (Approbation to Divrei Yosef) agreed with this position.
- Yalkut Yosef (Tzitzit Utefillin 30 fnt. 6) thoroughly rejects the position of Rav Masas. He says that Shulchan Aruch, Pri Chadash, Rav Chaim Abulafia, Rav Laniado, and Rabbi Faragi all lived in Israel, Eygpt or nearby and still held like Rabbeinu Tam.
- Orot Chaim Druk answers that and Bayit Neeman 1:25 s.v. mistabra argues that such a chiddush isn't found in the rishonim. Bayit Neeman 1:28 s.v. ureeh cites Sava Hashamayim (Rav Nissim Vidal v. 1 p. 162) who also had a similar suggestion that the sky needs to be dark enough to see 3 faint stars and argues on that as well. Bayit Neeman finally cites Rav Yonah Merzbach in Aleh Yonah p. 65 who disagreed with the Orot Chaim.
- Shulchan Aruch, Orach Chaim 293:3
- Bei'ur HaGra and Bei'ur Halacha, Orach Chaim 261:2 and Mishna Berurah 293:3
- Mayim Chaim of the Pri Chadash (5704 edition p. 116 s.v. ubemet) writes that Tosfot Pesachim 2a s.v. veha citing the Ri holds like the Geonim and Gra. Be'er Avraham (Pesachim 2a) agrees and asks why the earlier Poskim didn’t quote this Tosfot as a proof. Derech Yeshara Ben Hashemashot p. 124 and Ish Matzliach (MB v. 3 Kuntres Ben Hashemashot p. 91) also bring this proof. The First Lubevitcher Rebbe (the Alter Rebbe / Baal HaTanya) in Piskei HaSiddur (cited by Hazmanim Bhalacha 2:41:9) also says Tosfot Pesachim 2a holds like Geonim. The Hazmanim Bhalacha tries to avoid this reading in Tosfot but is confronted with a challenged by the text of the Tosfot Rash Mshantz and leaves it unresolved.
- The Maharam Alshaker 96 proves that the Rambam agrees with the Geonim that Ben Hashemashot is all of 0.75 mil and begins immediately after shekiya. One of his proofs is from Rav Avraham Ben Harambam's work "Alkafiya." Yabia Omer OC 2:21:4 disagrees and tries to show that the Rambam Pirush Mishnayot (Shabbat 2:6) holds like Rabbenu Tam. Ish Matzliach (Kuntres Ben Hashemashot MB v. 3) thoroughly tries to disprove Yabia Omer's contention and show that the Rambam thinks like the Geonim. Or Letzion 1 YD 10 also explains that the Rambam follows the Geonim.
- Maharam Alshakar 96, Shach YD 266:11, Graz (Piskei Hasiddur), Maharshag 1:38:1, Chazon Ish (Orchot Rabbenu v. 1 p. 127) all cited by Dor Hamelaktim v. 1 p. 413
- Dor Hamelaktim v. 1 p. 415 quotes the Har Tzvi cited in Tzitz Eliezer 17:2:4, Rav Shlomo Zalman Auerbach (Halichot Shlomo Chanuka 16:31), Rav Elyashiv (Tzohar 13:53:3), Tzitz Eliezer 17:2, Yabia Omer 7:41:2, Rav Nevinsal (Byitzchak Yikareh 261:3), and Shemesh Umagen 1:5, 2:18 writes that the minhag is like the Gra.
- Gra 261:12 states that the time for nightfall depends on one's location and the Gemara was only talking about the horizon in Bavel. Birur Halacha Tinyana p. 96 advocates for this position of extrapolating times based on degrees below horizon.
- This might be an American replication of the custom in Israel to wait 30 minutes, per the minhag of the Gr"a. A few minutes are added for Tosefet at the end of Shabbat. Rabbi Eli Belizyon ("Zmanei Hayom: Rabbeinu Tam vs The Geonim")
- Shu"t Igrot Moshe, Orach Chaim 4:62. Rav Moshe held that Binei Torah should be follow the opinion of Rabbeinu Tam. With that said, even Rabbeinu Tam would agree that in America, 50 minutes would suffice since all the stars are out by then. People should strive for 72 minutes as that was Rabbeinu Tam's opinion back in Europe, but 50 minutes is sufficient. Rabbi Yaakov Hoffman mustered evidence that in fact the minhag was always to keep Shabbat until 3 stars appeared and in practice were following the Geonim and even Rabbenu Tam never intended to institute a novel interpretation of Tzet Hakochavim.
- Ketzot HaShulchan 93:2. Shemirat Shabbat Kehilchata (ch. 20 fnt. 45) cites Rav Shlomo Zalman Auerbach as saying that the minhag is to consider it Ben Hashemashot for 25 minutes.
- Dinim V'Hanhagot 8:7 in the name of the Chazon Ish. Rav Aharon M'Belz instructed that one should wait 50 minutes after sunset in Israel. Bayit Neeman 1:28 deals with how the oral reports that the Chazon Ish for only 45 minutes after sunset fits with the letter of the Chazon Ish (Igrot 2:41) that seems to advocate following Rabbenu Tam.
- As stated by his son in-law, Rav Aharon Lichtenstein (etzion.org). Privately, Rav Soloveitchik followed the opinion of Rabbeinu Tam.
- Ben Ish Chai (Shana Sheniya, Vayetzeh n. 1). See Bayit Neeman 1:28 p. 184 s.v. vki who explains that the Ben Ish Chai was following the star observation method. He explains that most of those who wait 45 minutes like the Chazon Ish and Ben Ish Chai (for a shorter time) do so not because of Rav Tukachinsky's approach that rejects the Gra. Rather they all accept the Gra, yet they are strict to be sure that they see three small stars in the sky.
- Kaf HaChayim on Shulchan Arukh Orach Chayim 331:35:1 writes that minhag is to assume it is nighttime after 40 minutes in Jerusalem.
- Birur Halacha Tinyana p. 96
- Based on Gra
- Based on Rav Tukachinsky
- Zmanim Khalacha (p. 107, Table 8, Latitude 41, Motzei Shabbat as per R' Tukachinsky, Row Sept 22)
- Based on Rabbeinu Tam
- Rav Hershel Schachter in Bikvei Hatzoan 38:3 p. 260 explains that Rabbeinu Tam's position can not be added as a factor in a halachic question since it is based on a reality and it seems to us to be incorrect. Therefore, even elu v'elu divrei elokim chayim doesn't apply. For other reasons Bayit Neeman 1:25 agrees. He also quotes Rav Shlomo Zalman Auerbach (Puah p. 138 fnt. 61) as holding that one can't use Rabbeinu Tam as a factor.
- Rav Ovadia Yosef in Taharat Habayit v. 2 pp. 265-274 uses the opinion of Rabbeinu Tam as one factor in allowing a hefsek tahara after sunset. However, Bayit Neeman 1:25 p. 144 s.v. vod argues that Rabbeinu Tam's opinion was rejected as the halacha and therefore one may not accept it as a factor to be lenient. The only one halacha where the Bayit Neeman is willing to accept using Rabbeinu Tam to be lenient is davening mincha after sunset up to 13.5 minutes since that is the minhag.
- Yalkut Yosef 293:11