Sukka on Shmini Atzeres?
As the sun sets on Hoshana Rabba, effectively ending the holiday of Sukkos, an annual machlokes dawns. As with much related to the Yomim Tovim, different minhagim come to the forefront this time of year. Not just the Sukkos-long variances as to the proper method of nanuim with the Lulav and Esrog, nor the correct order of the Ushpizin. Rather, this author is referring to sitting in the Sukka on Shmini Atzeres. Is it an obligation or recommendation? Prohibited or permitted? Why do some go to great lengths to make sure to eat or even sleep in the Sukka on this day, while others will make due with a simple Kiddush or even less? This article sets out to address this annual Sukkos “battle”.
The Torah states in Parashas Emor that “the Eighth day”, the day following the weeklong holiday of Sukkos, is a holiday as well, and also “an Atzeres,” generally translated as an ‘Assembly’ or a day of ‘Stopping’ work. Rashi famously elucidates this interesting turn of phrase with the comment, “Atzarti Eschem Etzli”, that after a week of festivities, Hashem wishes to remain an extra day together with us, His children; reminiscent of a king who would do the same before taking leave of his children, to show how difficult it is to part from them.
This also means that this ‘extra’ day, colloquially known as Shmini Atzeres, is technically not part of Sukkos. Accordingly, on this day there is no Biblical obligation to do any of the Mitzvos exclusive to Sukkos: not shaking the Lulav nor eating in the Sukka. If so, why would anyone have a minhag to eat in the Sukka on Shmini Atzeres? It is an entirely separate Yom Tov!
To properly understand this, some Jewish History is in order, dating back several millennia. As long as the Sanhedrin in Eretz Yisrael established the New Month (Rosh Chodesh) based on eyewitnesses, far away places where Jews resided that did not receive messengers in time to tell them when the Rosh Chodesh was declared, would keep two days of Yom Tov instead of one. This was due to the uncertainty of which day Rosh Chodesh truly was and consequently when the Yomim Tovim actually fell out. This was done in order to ensure that no one should unwittingly transgress any Biblical prohibitions. Later, when much calendar confusion reigned due to the subversive efforts of the Kutim, Chazal decreed that in Chutz La’aretz (the Diaspora), “Yom Tov Sheini”, or a two-day Yom Tov, instead of the Biblically mandated one day, must be observed.
The Gemara itself (Beitzah 4b) actually asks the most common question regarding “Yom Tov Sheini”: ‘But now that we have a set calendar and we know in advance when Rosh Chodesh will be, why must we still observe a “two-day Yom Tov”?’The Gemara answers that in the times of Rabbi Elazar ben Pedasa message was sent from the Rabbanim of Eretz Yisrael to the Diaspora: “Hizharu B’Minhag Avoseichem B’Yadeichem”, ‘You should still be vigilant with the custom of your forefathers that has been handed down to you (meaning that they must still keep “Yom Tov Sheini”) because there might be times when the local government will issue a decree and it will cause confusion.”
This is not the only time that such a communiqué was sent from Eretz Yisrael to Chutz La’aretz mandating them to keep ‘Yom Tov Sheini’. In fact, the Yerushalmi records a similar occurrence, that after Chazal found out about a specific incident in Alexandria, Rabbi Yosi (bar Zavda) sent out a message that even though there was a set calendar (‘shekasvu lachem sidrei Moados’), still, “al tishnu Minhag Avoseichem”, “Do not deviate an iota from the custom set by your forefathers”, and observe ‘Yom Tov Sheini’.
Chazal were extremely strict with this Takana and even put someone in Cherem (excommunication) for violating this decree (see Gemara Pesachim 52a).
The outcome of this has long since become a famous dichotomy: in Eretz Yisrael where there never was a safek yom or “day in doubt”, since messengers would always be able to reach every community throughout Eretz Yisrael in time for Yom Tov, only one day of Yom Tov is celebrated, exactly as it is written in the Torah, while in Chutz La’aretz each day of Yom Tov has long since become a “two-day Yom Tov”.
However, it is important to note that this din of ‘Yom Tov Sheini’ only applies to the Shalosh Regalim: Pesach, Shavuos, and Sukkos. Other Yomim Tovim do not share this distinction due to various reasons. In fact, and although debated by the Rishonim, nowadays everyone must observe two days of Rosh Hashana, even in Yerushalayim, while all other holidays including Yom Kippur, Purim, and Chanuka, are observed worldwide as just one day.
Separate But Equal
With this background in mind, let us return to our humble Sukka. In Eretz Yisrael there are no aspects of Sukkos manifested on the separate and distinct holiday of Shmini Atzeres. In fact, it is simply celebrated as Simchas Torah.
Yet, this also compounds our original dilemma for everyone inChutz La’aretz. Since Yomim Tovim are celebrated as two days, what should be done on Shmini Atzeres in Chutz La’aretz? Is it treated as part and parcel of the preceding holiday of Sukkos, or does it maintain its exclusive status as a separate holiday? The upshot of this question would be whether one must still perform the Mitzvos of Sukkos on Shmini Atzeres or not.
Not a recent issue, the Gemara in Maseches Sukka (46b-47a) actually deals with this very subject: How Shmini Atzeres is viewed in halacha. After extensive debate the Gemara famously concludes l’halacha that on Shmini Atzeres “Maysiv Yasvinan, Brochi Lo Mevorchinan.” In other words, we must eat in the Sukka, but we don’t make the regularly mandated bracha of “leisheiv baSukka.” The Rosh explains that since Sukkos and Shmini Atzeres are separate and different holidays and have different sets of Mitzvos, we cannot perform all of their Mitzvos, as it would be ‘tarti desasri’, an outright contradiction. Rather, we only do what we can lechumra, meaning eating in the Sukka, but not making the blessing.
Another interesting result of this ruling is that we also do not wave the Arba Minim on Shmini Atzeres. The reason being that if Shmini Atzeres truly was a separate holiday, then waving the Arba Minim would not only be deemed unnecessary, they would be considered muktzah. Therefore, Chazal would not rule that we be required to do something that would potentially be a safek mitzvah / safek aveirah, and especially not to make a bracha on it! Tosafos adds that since a Lulav would be muktzah on Shmini Atzeres since it is a separate Yom Tov, waving it would clearly demonstrate that one is treating Shmini Atzeres like Chol Hamoed, whereas, in regard to eating in a Sukka, the act is not so noticeable because many people enjoy eating in a Sukka. Therefore, although waving the Arba Minim is out of the question on Shmini Atzeres, on the other hand, eating in the Sukka would not be considered ‘tarti desasri,’ and thus is mandated.
This dual ruling is duly codified as halacha by the Rambam, Sefer Hachinuch, Tur Shulchan Aruch andLevush, and as the Mishnah Berurah notes, followed by virtually all later Acharonim, that although we do not make the bracha of “leisheiv baSukka”, nevertheless, we are still required to eat in the Sukka on Shmini Atzeres.
Yet, something seems to be lacking in the application of this halacha. Forif this the proper conclusion, why are there divergent customs? And there most definitely are divergent customs here! There are those who sleep in the Sukka on Shmini Atzeres; those who don’t even step foot in the Sukka; those who only make Kiddush in the Sukka but eat the majority of their meals inside, and those who only eat in the Sukka but don’t sleep there. Which is correct?
To Sleep or Not to Sleep?
It is well known that the Vilna Gaon was very makpid not only to eat but also to sleep in the Sukka on Shmini Atzeres. The Chayei Adam relates that the Gr”a once made the whole yeshiva sleep in the Sukka on a freezing Shmini Atzeres night, just to show the rest of the city the importance of following this halacha. Several authorities rule like the Gr”a, saying that one must sleep in the Sukka on Shmini Atzeres, maintaining that there should not be a halachic difference between eating and sleeping in the Sukka.
However, most authorities do not agree with this reasoning and maintain that although one must eat in the Sukka on Shmini Atzeres, nevertheless, one does not (and some say nor should not) sleep in the Sukka. The Chasam Sofer famously did not sleep in the Sukka on Shmini Atzeres. This is also the conclusion of the Mishnah Berurah, who states that the “Minhag HaOlam” is not to sleep in the Sukka on Shmini Atzeres. However, the Kitzur Shulchan Aruch, who also acknowledges that the Minhag HaOlam is not to sleep in the Sukka, nevertheless concludes that it is still proper to do so anyway.
Surprisingly, and although not the common practice, it is known that the Gadol HaDor Rav Moshe Feinstein zt”l, was extremely makpid on sleeping in the Sukka, even when it was freezing outside and even on Shmini Atzeres. He explained that his father, Rav Dovid zt”l, was particularly vigilant with sleeping in the Sukka and in what was to be the last year of his life, caught pneumonia from doing so one freezing Shmini Atzeres, and passed away six days later. Rav Moshe related that he learned from this tragedy the lengths of Mesiras Nefesh required of himself to sleep in a Sukka, and even on Shmini Atzeres.
Not to Eat ?
However, on the opposite end of the halachic spectrum, there were many great authorities who ardently defended those who follow a minhag of not even eating in the Sukka on Shmini Atzeres. These include the Baal Shem Tov, Sfas Emes, Aruch Hashulchan, Kozeglover Gaon, and the Minchas Elazar. Moreover, there is record, even among the Rishonim, of certain Rabbanim and specific well-known families who ate indoors on Shmini Atzeres. Rav Tzadok HaKohen of Lublin wrote an over-60 page halachic sefer titled “Meishiv Tzedek” defending the practice of not eating in the Sukka on Shmini Atzeres. Even the Chayei Adam and the Maharsham (although not ruling this way), cite minhagim to eat only partially in the Sukka, such as simply making Kiddush in the Sukka, but having the bulk of the Seudah inside.
Many of these authorities base their hetter on the Korban Nesanel, who writes that since eating in the Sukka on Shmini Atzeres is only mandated due to a safek, therefore, in places where it is cold and windy, one is not required to do so. Others understand that the Gemara’s conclusion of “Maysiv Yasvinan, Bruchi Lo Mevorchinan” meant that one may eat in the Sukka on Shmini Atzeres without the bracha of “leisheiv baSukka”, but not that one is actually obligated to. There is even a recently published manuscript of a Rishon, Rav Yehuda ben Klonimos, the Rebbi of the Rokeach, who maintains that the Gemara’s conclusion was actually added in later to the Gemara and is not authoritative.
Interestingly, many centuries prior, the Midrash Tanchuma, implied that one does not have to eat in the Sukka on Shmini Atzeres, but for a very different reason: “in order so that one should be able to (properly) daven for rain with a ‘lev shalem.’” Since Tefillas Geshem (or is it Gashem?) is recited on Shmini Atzeres, if one’s tefillos would be answered right away, he would be rained out of his Sukka! Additionally, the Yerushalmi as well as Targum Yonason / Yerushalmi, state that one should eat indoors on Shmini Atzeres (although it must be noted that this may not be a strong proof, as it has been argued that that is likely that these passages may simply be referring to Bnei Eretz Yisrael).
Either way, different minhagim of not exclusively eating in the Sukka on Shmini Atzeres have earned staunch following, even though they run contrary to the normative halacha.
This author realizes that at this point readers in Israel are probably saying that this is all very nice, but this doesn’t affect them; they only keep one day, Simchas Torah! No safek yom here! But actually it just might concern them. For what is a “Chutznik” or two-day Yom Tov keeper who happens to be in Israel for Sukkos (quite commonly yeshiva bochurim) to do?
Although the famed Chacham Tzvi, and later the Shulchan Aruch Harav, ruled that even one merely visiting Eretz Yisrael over Yom Tov should keep only one day of Yom Tov like the natives, (to paraphrase: “when in Israel do as the Israelis”), nevertheless, the vast majority of halachic authorities, including the author of the Shulchan Aruch himself and even the Chacham Tzvi’s own son, Rav Yaakov Emden, maintained that vistors’ status is dependant on whether or not their intention is to stay and live in Eretz Yisrael, known as ‘im da’atam lachzor’. This dictum is based on Gemara Pesachim (51a-b) regarding Rabba Bar Bar Chana, Rav Ashi, and Rav Safra. As elucidated by Rav Yosef Karo zt”l, author of the Shulchan Aruch, in his responsa (Shu”t Avkas Rochel 26), anyone who has Da’as Lachzor, intention to return, maintains his original status as if he were still in the place from ‘whence he came’.
Practically, this means that if one is planning on living in Eretz Yisrael he would keep only one day of Yom Tov. Correspondingly, if planning on returning to Chutz La’aretz, one must still observe a two day Yom Tov, even while currently staying in Eretz Yisrael.
Back to our bochurim, since these striving students are generally only based in Eretz Yisrael temporarily, according to the majority halachic consensus they must still keep the second day of Yom Tov in Israel as well. However, this leads us to another issue; one not mentioned in halachic literature until modern times: Must these visitors, who are keeping ‘Yom Tov Sheini’ in Eretz Yisrael still sit in a Sukka on Shmini Atzeres, or may they do as the Romans…err, Israelis do?
Remarkably, contemporary halachic decisors are divided as to the proper halacha, with no clear cut ruling. Rav Yechiel Michel Tukachinsky, Rav Shlomo Zalman Auerbach, the Minchas Yitzchak, the Shemiras Shabbos K’hilchasa, and Netei Gavriel rule that a “Chutznik” should not eat in a Sukka in Israel on Shmini Atzeres. They explain that one should not be stringent on a safek yom that does not apply where they currently are, especially as the whole rule of keeping two days in Eretz Yisrael is a matter of dispute. Additionally, sitting in a Sukka publicly when the locals do not, might be of halachic concern.
On the other hand, other contemporary authorities, including Rav Moshe Feinstein, Rav Yosef Shalom Elyashiv, Rav Chaim Pinchas Scheinberg, Rav Shmuel Halevi Wosner, and the Debreciner Rav, rule that someone who always keeps ‘Yom Tov Sheini’ must continue to keep it to its full extent - even in Eretz Yisrael. This includes sitting in the Sukka on Shmini Atzeres, even though the locals do not.
A third opinion, a middle ground approach, is that of Rav Ben Tzion Abba Shaul, the Betzeil Hachochma, and Rav Ovadia Yosef. They agree that a Chutznik should preferably eat in a Sukka on Shmini Atzeres in Eretz Yisrael. However, these authorities make an exception for a ‘visitor’ who is dependant on locals for his meals, as they aver that a guest is not obligated to cause undo hardship for his hosts. Following this ruling would mean that an American bochur eating with Yerushalmi relatives who are having their Yom Tov seudah inside, may indeed eat with them in their home, and is not obligated to trek out to find a Sukka. As with any other halachic question, one should ask his own Rabbinic authority which opinion he should personally follow.
An interesting and important outcome of this three way Israeli machlokes is that it sheds some light on how many contemporary halachic decisors ruled regarding several other issues mentioned previously in this article. For, although they disagree on what an American bochur should do while in Eretz Yisrael for Shmini Atzeres, nevertheless, their disparate positions clearly show that all of the aforementioned contemporary authorities agree that in Chutz La’aretz one must eat in the Sukka on Shmini Atzeres, and that visitors to Eretz Yisrael are dependant on whether da’atam lachzor or not, and if one meets that requirement he must keep ‘Yom Tov Sheini’ there.
In Parashas Re’eh, Moshe Rabbeinu tells us that “Banim Attem La’Hashem Elokeichem,” Hashem considers us His children. Which Yom Tov can possibly lay claim to exemplify this notion more than Shmini Atzeres, a day that Hashem kivyachol personally requests to stay with us? Whatever one’s minhag is on this ‘extra’ day, we should all merit feeling the embrace and protection of HaKadosh Baruch Hu all Yom Tov long!
This article was written L'iluy Nishmas Shoshana Leah bas Yaakov Eliezer and the Rosh HaYeshiva - Rav Chonoh Menachem Mendel ben R' Yechezkel Shraga and l’zechus for Shira Yaffa bas Rochel Miriam v’chol yotzei chalatzeha for a yeshua sheleimah teikif umiyad!
For any questions, comments or for the full Mareh Mekomos / sources, please email the author: email@example.com.
Rabbi Yehuda Spitz, author of M’Shulchan Yehuda on Inyanei Halacha, serves as the Sho’el U’Meishiv and Rosh Chabura of the Ohr Lagolah Halacha Kollel at Yeshivas Ohr Somayach in Yerushalayim. He also currently writes a contemporary halacha column for the Ohr Somayach website titled “Insights Into Halacha”. http://ohr.edu/this_week/insights_into_halacha/.
 Vayikra (Ch. 23:36).
 Rashi (ad loc. s.v. atzeres hi). This is also cited by the Sefer Hachinuch (Parashas Emor, Mitzva 323:1 s.v. kvar and 324:1 s.v. v’taam), quoting the Midrash. The Machon Yerushalayim edition of the Minchas Chinuch (ad loc. in the footnotes) identifies it as Midrash Rabba (Bamidbar Ch. 21:24), Midrash Hagadol (Shemos Ch. 29:36), and Pesikta D’Rav Kahana (30).
 See Rambam (Hilchos Kiddush Hachodesh Ch. 3:11 and Ch. 5:4).
 See Gemara (Beitzah 4b and Rosh Hashana 21a; and commentaries), Yerushalmi Rosh Hashana (Ch. 2, Halacha 1), Shu”t HaGaonim Lyck (1, which cites Rav Hai Gaon and other Gaonim explaining that this Takana actually dates to the times of Yechezkel and Daniel, and possibly even Yehoshua bin Nun, [Rav Saadiah Gaon held it was halacha l’Moshe M’Sinai!]; referenced in Shaar Hatziyun 496, 1), Rambam (Hilchos Kiddush Hachodesh Ch. 5:6), Sefer Hachinuch (Parashas Emor, Mitzva 301; and Minchas Chinuch ad loc.), Tur and Shulchan Aruch and main commentaries to Orach Chaim 496, Magen V’Tzina (pg. 7b), Kuzari Hasheini (Matteh Dan, pg. 83 and 241), Maharitz Chiyus (Darchei Horaah pg. 7-8), Tiferes Yisrael (Mishnayos Ediyos Ch. 1, Mishnah 6:35), Rav Yisrael Moshe Chazzan’s ‘Kedushas Yom Tov’, Shu”t Yad Eliezer (131), Shu”t Shaar Asher (Orach Chaim 8), Sdei Chemed (vol. 6, Ma’areches Yom Tov 2:8), Chazon Ish (Hilchos Yom Tov, Orach Chaim 130), Rav Yechiel Michel Tukachinsky’s Ir Hakodesh V’Hamikdash (vol. 3, Chapters 18 and 19), and the forward to Rabbi Yerachmiel Dovid Fried’s classic sefer Yom Tov Sheini K’Hilchaso at length. See also Meshech Chochma (Parashas Bo, Beginning of Ch. 12, s.v. uvazeh) who offers a compelling reason why ‘Yom Tov Sheini’ still applies nowadays – “gezeira shema yivneh Bais Hamikdash.”
 Rashi (ad loc. s.v. d’gazri) clarifies that this is referring to calendar confusion. He explains that the government will decree against learning Torah and the ‘sod haIbur’ (the principle of the intercalation of the New Month) will be forgotten, and if they revert to keeping one day of Yom Tov, they might establish a ‘Chasar’ month as a ‘Malei’ or vice versa, and Klal Yisrael will possibly (Chas V’Shalom) end up eating Chametz on Pesach. Although the Gemara does not specify which Amora sent this message, nor to which community in Chutz La’aretz it was sent, nevertheless, the Gemara’s unique choice of phraseology “shalchu mesum”, clues us in that it denotes a message sent by Rabbi Elazar ben Pedas, as explained in Gemara Sanhedrin (17b) and Rashi’s commentary to Gemara Shabbos (19b s.v. R’ Elazar). See Ir Hakodesh V’Hamikdash (vol. 3, Ch. 19:1). [Interestingly, the Meiri (Beis HaBechira on Sanhedrin ad loc.) has a different Girsa in the Gemara; he quotes the expression “shalchu mesum” as indicating a missive from Rabbi Yirmiya!] See also Shu”t Goren Dovid (Orach Chaim 41) who utilizes the infamous 1242 burning of 24 wagonloads of Gemaros and Kisvei Rishonim in France as a reason to explain why nowadays Yom Tov Sheini is still observed. [For more on this topic see recent article titled ‘Forgotten Fast Days: Zos Chukas HaTorah’]. Unfortunately, throughout our long and bitter Galus we never know when a government might make a gezeira ra’ah and consequently all halachic literature lost. How then will we be able to properly calculate the months and years to know when are the correct days to observe? He explains that this tragedy was a fulfillment of the Gemara’s warning to keep Yom Tov Sheini, “Hizharu B’Minhag Avoseichem B’Yadeichem”.
 Yerushalmi (Eruvin Ch. 3, end Halacha 9; see also Korban HaEida ad loc.).
 Interestingly, there are several contemporary authorities who were of the opinion that in places in Eretz Yisrael where the messengers did not or possibly did not reach, Yom Tov Sheini must still be observed. This debate seems to be based on several enigmatic passages in the Rambam (see Hilchos Kiddush HaChodesh Ch. 5:5, 6, 9, 10, 11, and 12), whether he was referring exclusively to Chutz La’aretz or even in Eretz Yisrael as depending on the messengers. See Shu”t Maharit Tzahalon (216; cited in Birkei Yosef, Orach Chaim 496), Shu”t She’elas Yaavetz (vol. 1:168), Minchas Chinuch (Parashas Emor, Mitzva 301, 1 s.v. v’hinei shittas and v’ode), Shu”t Tzafnas Pane’ach (vol. 1:51; pg. 117), Chazon Ish (Orach Chaim 132:1 - 3), and Orchos Rabbeinu (vol. 2, pg. 113-115). It is well known that the Brisker Rav was stringent for this opinion and kept Yom Tov Sheini - in Yerushalayim! [However, Rav Shlomo Zalman Auerbach (cited in Yom Tov Sheini K’Hilchaso pg. 488-489) and Rav Moshe Sternbuch (Shu”t Moadim U’Zmanim vol. 8, Hosafos to vol. 3:221) questioned this stringency, as even if the halacha was dependant on messengers, certainly they would have reached all corners of Yerushalayim!] However, the halacha pesuka follows the opinion of the Ritva (Rosh Hashana 18a s.v. v’al and Sukka 43a s.v. d’parich) and Sefer HaChinuch (Parashas Emor, Mitzva 301) and most other Rishonim [including possibly even the Rambam - as there are differing opinions as to his true intent]. See Shu”t Avnei Nezer (Orach Chaim 392:9), Ir Hakodesh V’Hamikdash (vol. 3, Ch. 19; at length), Chazon Ish (Orach Chaim 132, end 2), Shu”t Tzitz HaKodesh (vol. 1:41 and 42), Shu”t Tzitz Eliezer (vol. 3:23), Mikraei Kodesh (Pesach vol. 2:57 and 58), Shu”t Yaskil Avdi (vol. 6:2), and Yom Tov Sheini K’Hilchaso (Ch. 18 and in footnotes - at length - also citing the psakim of Rav Shlomo Zalman Auerbach and Rav Yosef Shalom Elyashiv). For more on this fascinating topic see Yom Tov Sheini K’Hilchaso (Miluim 4), who delves into this inyan at great length.
 Chazal established a Yom Tov Sheini for Shavuos, in order not to make a distinction between the Yomim Tovim, even though the messengers of Tishrei and Nissan would certainly have reached even far flung places by then. See Rambam (Hilchos Kiddush Hachodesh Ch. 3:12), Shu”t Chasam Sofer (Orach Chaim 146 and Yoreh Deah 252), Shu”t Sho’el U’Meishiv (Mahadura Tinyana vol. 2:85 s.v. v’hinei l’fan”d) and Shu”t Machazeh Avraham (Orach Chaim 121). See also Chiddushei Maran Ri”z HaLevi al HaTorah (Parashas Emor); according to the Brisker Rav, the exact date of Shavuos is always already set from the beginning of Nisan, as the pasuk states regarding Shavuos (Parashas Emor Ch. 23:21) that it is observed “b’etzem hayom hazeh”.
 See Rava’s statement (Beitzah 5a) regarding the aftermath of Rav Yochanon ben Zakkai’s Takana that testimony of the New Moon was accepted all day, that when Eidim would come later in the day, “min haMincha u’lemaaleh”, the Sanhedrin would establish both days as Yom Tov. The Rif (Beitzah 3a in his pagination) derives from this that even Bnei Eretz Yisrael are mandated to observe Rosh Hashana as a two day Yom Tov. However, Rabbeinu Efraim (cited by the Ran ad loc. s.v. v’kasav) and the Baal Hamaor (Meor Hakattan ad loc. 2b s.v. v’haRif) strongly disagreed, discounting this logic, and maintaining that Rosh Hashana should be (and always was) observed as one day in Eretz Yisrael. Yet, the Ramban (Milchemos Hashem ad loc. 2b s.v v’od v’harav) and Rosh (Beitzah Ch. 1:4) ardently defend the Rif’s conclusion, and maintain that even in Eretz Yisrael Rosh Hashana need be observed as a two day Yom Tov. This is also the conclusion of the Rashba (Beitzah 5b; albeit for different reasons than the Rif), Rambam (Hilchos Kiddush Hachodesh Ch. 5:12 and Hilchos Yom Tov Ch. 1:1 and 24) and Sefer Hachinuch (Parashas Emor, Mitzva 301, end 2). See also Rashi (Beitzah 5a s.v. m’takanas and ha) and Tosafos (ad loc. s.v. ha). Interestingly, this actually was not simply a theoretical debate, but rather was practical – as this sheilah – sent from Eretz Yisrael - was originally addressed to Rav Hai Gaon about their custom (in his time) of keeping only one day of Rosh Hashana in Eretz Yisrael. Rav Hai Gaon’s response (Shu”t HaGaonim Lyck 1; and later seconded by the Rif, et al. ibid.) was that their ‘minhag’ was a mistake, as the Takana of keeping two days of Rosh Hashana in Eretz Yisrael actually dated to the times of Yechezkel and Daniel, and possibly even Yehoshua bin Nun, and was not simply due to safek yom. See next footnote. It is unclear how large this community was and for how long this minhag was kept, but it seems that certainly by the Rambam’s time, Bnei Eretz Yisrael were all keeping two days Rosh Hashana. Thanks are due to Michael Volpo for pointing this out.
 This majority opinion of the Rishonim (see previous footnote) is codified as halacha in Shulchan Aruch (Orach Chaim 601:2), since even during the times of the Beis Hamikdash, Rosh Hashana was sometimes observed as a two day Yom Tov [see Beis Yosef (ad loc. s.v. v’kasav), Magen Avraham (ad loc. 1), Chayei Adam (vol. 2, 139:14), Matteh Efraim (601:12), Aruch Hashulchan (Orach Chaim 600:1 and 2), and Mishnah Berurah (601:3)]. In fact, the two day Yom Tov of Rosh Hashana is mentioned in the Mishnah (Menachos Ch. 11:9) and was known to have already been observed in the times of Ezra HaSofer (see Nechemia Ch. 8:13, and commentaries ad loc.). The Yerushalmi (end of the first Perek of Eruvin) effectively dates this Takana back to the times of the Neviim Rishonim! There are practical Halachic differences between a standard ‘Yom Tov Sheini’ and the second day of Rosh Hashana, though. Since Rosh Hashana was established by Takana, and not due to safek Yom (see next footnote), the second day shares first day Yom Tov status (referred to as ‘kedusha achas hein’ or ‘yoma arichta’) and generally does not share the Yom Tov Sheini dispensations listed in Orach Chaim 496. See Rambam (Hilchos Yom Tov Ch. 1:24), Tur (Orach Chaim 503:1 and 600:1), Shulchan Aruch (Orach Chaim 513:5 and 515:1), Chayei Adam (vol. 2, 139:14), Kitzur Shulchan Aruch (99:2, in the parenthesis), Aruch Hashulchan (Orach Chaim 600; at length), and Kaf Hachaim (Orach Chaim 503:10 and 600:1). For more on the status and parameters of Rosh Hashana as a two day Yom Tov see Minchas Chinuch (Parashas Emor, Mitzva 301:5 s.v. chutz), Shu”t Sho’el U’Meishiv (Mahadura Tinyana vol. 2:85), Chazon Ish (Orach Chaim 130 and 131), Shalom Yehuda (vol. 1, Moed, 1), Ir Hakodesh V’Hamikdash (vol. 3, Ch. 18), Kaf Hachaim (Orach Chaim 601:5; who cites several Kabbalistic reasons) and Yom Tov Sheini K’Hilchaso (Miluim 6).
 See Rabbi Yechiel Michel Tukachinsky’s Ir Hakodesh V’Hamikdash (vol. 3, Chapter 18:5, pg. 236-238) who deals with this issue at length. Although certainly in the city of Yerushalayim it would have been known when the Sanhedrin would have established the New Month and Year, he concludes that the two day Yom Tov regarding Rosh Hashana that applies universally was not due to the safek Yom, but rather was an actual Takanas Sanhedrin from when the Bais Hamikdash was still standing [see also Rambam (Hilchos Kiddush Hachodesh Ch. 5:12 and Hilchos Yom Tov Ch. 1:24) and Sefer Hachinuch (Parashas Emor, Mitzva 301:end 2); as mentioned previously, the Yerushalmi (end of the first Perek of Eruvin) dates this Takana to the times of the Neviim Rishonim], and is therefore as binding as if it was given at Har Sinai, and even in Yerushalayim.
 Although the Tur (Orach Chaim 624) states that ‘Chassidim and Anshei Maaseh’ would keep two days of Yom Kippur, nevertheless, the halachic consensus is that it is preferable not to; one of the main reasons being the sakana involved (based on the Yerushalmi in Maseches Challah Ch. 1). These poskim include the Ohr Zarua (vol. 2:281), Bais Yosef (Orach Chaim 624), Rema (ad loc. 5), Bach (ad loc.), Magen Avraham (ad loc. end 7), Biur HaGr”a (ad loc. s.v. v’ain linhog), Chasam Sofer (Hagahos ad loc.), Chayei Adam (vol. 2, 145:43), Matteh Efraim (625:10), Hisorerus Teshuva (Shu”t vol. 1:190), Aruch Hashulchan (Orach Chaim 624:5), and Mishnah Berurah (ad loc. 17). They explain that nowadays the calendar is set and there really is no more safek yom, yet the reason we are still stringent with ‘Yom Tov Sheini’ is due to Minhag Avoseinu and the Takana involved. However, there never was a Takana or minhag regarding keeping a two day Yom Kippur due to the potential Sakana. Therefore there would be no reason to keep a two day fast. The most famous contemporary example of keeping Yom Kippur for two days was during World War II, when the Mir Yeshiva, thanks to the efforts of Japanese diplomat Chiune Sugihara, managed to escape the Nazis by fleeing eastward and were ‘shanghaied’ in Kobe, Japan (and later in Shanghai itself). This was due to the safek yom from the International Date Line, and not the standard safek yom referred to in this article. However, before one decides to take on such an undertaking without any other mitigating circumstance, he should realize that he would halachically be beholden to keep a two day Yom Kippur for the rest of his life.
 The Abudraham (Seder Tefillas Purim U’Pirusheha), quoting the Mishmeres Hamoados, cites three reasons why Purim is not observed as a two-day Yom Tov: 1) Purim is a Rabbinic holiday and the same Rabbanim who established it were the same ones who established our calendar and Purim as a one day holiday. 2) Megillas Esther, when describing the holiday (Ch. 9:27) states ‘v’lo ya’avor’, meaning whomever celebrates it on one day cannot do so on another day [The three day ‘Purim Meshulash’ that is celebrated in Yerushalayim when Shushan Purim falls out on Shabbos is not an actual three day Yom Tov. Each separate day has unique observances of Purim. Friday’s is the Megillah reading and Matanos L’evyonim. Shabbos has Al HaNissim and the special Purim Maftir, and Sunday has Mishloach Manos and the Purim Seudah]. 3) Whichever day one would have read the Megillah on he would already have fulfilled his obligation. Several of these reasons are echoed by the Taz (Orach Chaim 688:4), quoting the Mordechai and Rashal, and the Minchas Chinuch (Parashas Emor, Mitzva 301:6). See also Shu”t Dovev Meisharim (vol. 1:15).
 The Abudraham (Seder Tefillas Chanuka), quoting the Baal Ha’Itim, explains that the reason why Chanuka is not celebrated as a nine day holiday is that Chanuka is a Rabbinic holiday and the same Rabbanim who established it were the same ones who established our calendar and Chanuka as a eight day holiday. See also Ateres Zekainim (Orach Chaim 670 s.v. b’ch”h b’Kislev) who cites a different reason from the Mahar”a Mizrachi, and Minchas Chinuch (Parashas Emor, Mitzva 301:6). He maintains that when the Beis Hamikdash will be rebuilt and Klal Yisrael reverts back to Kiddush Hachodesh via witnesses, it is possible that there might be a 9 day Chanuka in outlying areas.
 Rosh (Sukka Ch. 4:end 5).
 Another remarkable outcome based on this ‘tarti desasri’ is that the vast majority of halachic decisors disagree with the Taz’s lenient opinion (Orach Chaim 668:1 s.v. eilu divrei), and rule that one may not be mekabel Yom Tov early on Shmini Atzeres (unless in extremely extenuating circumstances). The reason is that even if one would be mekabel Shmini Atzeres early, it would still technically be the seventh day of Sukkos and any seudah would be required to be held in the Sukka - with a bracha of ‘leishev baSukka,’ which would be a potential bracha levattalah if it were truly no longer Sukkos. These poskim include the Rashal (Shu”t 68; who rules like Rav Tevil), Bach (Orach Chaim 668:1), Levush (Orach Chaim 668:1), Magen Avraham (ad loc. 3), Elyah Rabba (ad loc. 3), Matteh Moshe (970), Pri Megadim (Orach Chaim 668, Eishel Avraham 3), Chida (Birkei Yosef ad loc. 5), Chayei Adam (vol. 2,153:5), Chemed Moshe (cited in Shaar Hatziyun ad loc. 11), Nahar Shalom (Orach Chaim 668:1), Noda B’Yehuda (Dagul Mervava ad loc. s.v. b’Taz), Rav Yaakov Emden (Mor U’Ketziah ad loc. s.v. v’ani), Bigdei Yesha (cited in Shaar Hatziyun ad loc. 11), Minchas Chinuch (Parashas Emor, Mitzva 323:2), Aruch Hashulchan (ad loc. 4), Ben Ish Chai (Year 1, Parashas V’zos Habracha 13), Mishnah Berurah (Orach Chaim 668:7 and Shaar Hatziyun 11 and 12), and Kaf Hachaim (ad loc. 10). However, many later authorities tried to find makom l’smoch on the Taz’s shittah, perhaps as a tziruf, etc. See Shu”t Shoel U'Meishiv (Mahadura Tiny ana vol. 2:9), Shu”t Hisorerus Teshuva (vol. 1:97), Shu”t Chesed L’Avraham (vol. 2, Orach Chaim 70), Shu”t Yefei Nof (Orach Chaim 121), Shu”t Yismach Lev (Orach Chaim 15), Shu”t Mishnah Sachir (vol. 2, 181:5), Shu”t Binyan Olam (Orach Chaim, 7, s.v. v’yesh), Shu”t Ba’er Sarim (vol. 4:38), Shu”t Arugos Habosem (Orach Chaim 189), Shu”t Divrei Yatziv (Orach Chaim vol. 2, 226:6-7), and Rav Leib Malin’s Ohr Simcha (Ch. 15, page 27; he answers the apparent contradiction in the Taz’s shitta to that of him requiring ‘Temimus’ by Shavuos in Orach Chaim beg. 494 s.v. me’acharin). For more on the distinction between Shavuos and other Yomim Tovim and Shabbos, see Rav Betzalel Zolty’s Shu”t Mishnas Yaavetz (vol. 1, Orach Chaim 29, Kiddush B’Leil Chag Shavuos; he concludes that there is no din of Tosefes Yom Tov on Shavuos).
 Tosafos (Sukka 47a s.v. maysiv).
 Rambam (Hilchos Sukka Ch. 7:13), Sefer Hachinuch (Parashas Emor, Mitzvah 323:1), Tur, Shulchan Aruch, and Levush (Orach Chaim 668:1).
 Shaar Hatziyun (ad loc. 3), citing the Magen Avraham (ad loc. 2), Yaavetz (Siddur, Dinei Shmini Atzeres), Derech Hachaim (Dinei Sukka B’Shmini 2), Chayei Adam (ibid.), and Bikurei Yaakov (ad loc. 5), among others, as well as “shaarei Acharonim.” The same is ruled by the Vilna Gaon (Maaseh Rav 222), Matteh Efraim (625:31), Kitzur Shulchan Aruch (138:4), Ben Ish Chai (Year 1, Parashas V’zos Habracha 13), Aruch Hashulchan (ad loc. 2; although he later gives a limud zechus for those who do not), and Kaf Hachaim (ad loc. 8), that one must eat all of his meals in the Sukka on Shmini Atzeres. In a similar vein, the Chida (Birkei Yosef ad loc. 4; cited by the Shaarei Teshuva ad loc. 3) maintains that even Bnei Eretz Yisrael who are merely visiting Chutz La’aretz over Sukkos must nevertheless eat in the Sukka with their hosts (but not sleep), “shelo lezalzel B’Yom Tov Sheini”, all the while telling themselves “she’ein osim meshum mitzvah,” and secretly eat something out of the Sukka as well (to prove it is no longer actually Sukkos for him).
 See Tur (Orach Chaim 668; referring to such minhagim of eating partially in the Sukka as “v’aino minhag”), Beis Yosef (ad loc.; who interestingly defends not eating in the Sukka at night as there may be a potential ‘tarti d’sasri’ if one makes a Shehechiyanu as part of Kiddush on Shmini Atzeres while sitting in the Sukka; albeit it is noteworthy that he does not make such allowance in his final ruling on the subject in his Shulchan Aruch ad loc.), Magen Avraham (ad loc. 2), Ba’er Heitiv (ad loc. 3), Shaarei Teshuva (ad loc. 3), Chayei Adam (vol. 2, 153:5), Mishnah Berurah (ad loc. 6 and Shaar Hatziyun 4-8), and Kaf Hachaim (ad loc. 5) who cite these various minhagim.
 Maaseh Rav (222), Chayei Adam (vol. 2, 153:5), Shaar Hatziyun (668:4). This is also the mashmaos of the Beis Yosef (ad loc. s.v. v’ochlin), although strangely absent in his later authoritative Shulchan Aruch, that poskim do not make a distinction between eating and sleeping in the Sukka on Shmini Atzeres.
 Including the Bikurei Yaakov (Orach Chaim 668:4), citing proof from the Rashba (Rosh Hashana 15a) and also mentioning that Rav Nosson Adler did so as well, the Elyah Rabba (ad loc. 4), citing the Agudah (Sukka 43), the Divrei Malkiel (Shu”t vol. 1:32), Ben Ish Chai (Year 1, Parashas V’Zos Habracha 13), and Kaf Hachaim (Orach Chaim 668:5), who cites precedence from the Ritva (Rosh Hashana 31) and others, all of whom rule that one must also sleep in the Sukka on Shmini Atzeres.
This is opinion of the Ravyah (562; cited by the Mordechai in his glosses to Sukka 772) which is defended by the Rema (Darchei Moshe, Orach Chaim 663:3) and Levush (ad loc.) from the Beis Yosef’s challenge. The Maharil (Seder HaTefillos Chag HaSukkos 13) held this way, as did many later Acharonim, including the Noda B’Yehuda (Shu”t Mahadura Kama Orach Chaim 40), Shoel U’Meishiv (Shu”t Mahadura Rivi’ei vol. 2:120), Derech Hachaim (Dinei Sukka B’Shmini 2), Ksav Sofer (Shu”t Orach Chaim 120), Divrei Yisrael (Shu”t vol. 1:200), and Rav Shlomo Kluger (Hagahos Chochmas Shlomo to Orach Chaim 668), who prove that the Ravyah is correct, and one does not sleep in a Sukka on Shmini Atzeres. The Minchas Ani (Shu”t 25:1), although ruling that one should treat being in the Sukka on Shmini Atzeres the same as the rest of Sukkos, nevertheless was upset at those who held that one should be more stringent regarding the Sukka on Shmini Atzeres, as eating in the Sukka on Shmini Atzeres is a derabbanan m’taam safek, as opposed to the rest of Sukkos.
Shu”t Ksav Sofer (Orach Chaim 120 s.v. vchein ra’isi). See also Shu”t Hisorerus Teshuva (vol. 1:18 and vol. 2:25) who defends this shitta of his grandfather, the Chasam Sofer.
 Mishnah Berurah (668:8). However, the Kitzur Shulchan Aruch (138:5) who also acknowledges that the Minhag HaOlam is not to sleep in the Sukka, nonetheless still concludes that it is proper to do so anyway.
 This shitta of Rav Moshe’s is cited in sefer Shmaatsah D’Moshe (Shmuos Moshe, Hilchos Lulav 640:2 & footnote 18 and 668:1 and footnote 9).
 Baal Shem Tov al HaTorah (Sukkos 2), Kitzur Shulchan Aruch Beis Achiyah L’Baal Shem Tov (pg. 50), Sfas Emes (Sukka 47a s.v. maysiv; cited in Piskei Teshuvos vol. 6, pg. 455, footnote 3), Aruch Hashulchan (Orach Chaim 668:2-5; who is melamed zechus for those who do not eat nor sleep in the Sukka, and explains that a hekker is needed between our actions in the Sukka during Sukkos and those on Shmini Atzeres in colder climates, otherwise it appears that one is doing so exclusively for mitzvah, which would be problematic on Shmini Atzeres), Shu”t Eretz Tzvi (vol. 1:98), and Shu”t Minchas Elazar (vol. 4:31). The Minchas Elazar adds an additional reason to be lenient, based on Tosafos’ comments about waving the Lulav (see footnote 17). He equates eating in the Sukka on Shmini Atzeres in a colder climate with waving the Lulav on Shmini Atzeres, maintaining that neither should be done because it is apparent that one is doing it exclusively for the Mitzvah and will look like a ‘tarti desasri.’ Others who defend this minhag, at least partially, include the Yosef Ometz (Minhag Frankfurt, 1058; while writing that one must eat in the Sukka on Shmini Atzeres and anyone who only eats partially in the Sukka “lo shapir avdu”, nonetheless mentions that the Taryosh (or perhaps Troyes) family have a long-standing minhag not to eat in the Sukka on Shmini Atzeres, “v’yeish lahem al mah lismoch”), Elef Hamagen (on the Matteh Efraim; Orach Chaim 625:42; who cites many Gedolim who were lenient, although he ultimately concludes that nevertheless one should still eat in the Sukka), Katzeh Hamatteh (on the Matteh Efraim ad loc. 60), Shu”t Chedvas Yaakov (Tinyana 127), Shu”t Bais Yisrael (Orach Chaim 107), Shu”t Chok Moshe (27), Rosh Yosef (Ishkapa; 665), Rav Yitzchak Isaac Yechiel of Kamarna (in his Heichal Bracha al HaTorah commentary to Parashas Emor, Vayikra Ch. 23:36, as well asOtzar Hachaim, Mitzva 326 and 456; cited in the beginning of sefer Heichal Kamarna on Sukkos; he adds that the Gemara’s rule of Maysiv Yasvinan on Shmini Atzeres only applied in Bavel where it was pleasant to sit in the Sukka this time of year), Taamei HaMinhagim (822, pg. 358), Shu”t Maharshag (vol. 1:35), Shu”t Divrei Yaakov (77), Shu”t Toras Yekusiel (Tinyana 98), Lekutei Mahariach (vol. 3, pg. 106b, Seder Shmini Atzeres), Minhagei Kamarna (Sukkos 513 and footnote ad loc.), and She’arim Metzuyanim B’Halacha (138:3).
 See Rashi’s Sefer HaPardes (pg. 240, inyan Sukka s.v. Rabbeinu Shlomo), citing several Gedolim who ate indoors based on the Yerushalmi (ibid.; however, see footnote 34), and the Maharil’s Sefer HaMinhagim (Hilchos Lulav 6 s.v. amar lanu), citing the Mahari Segal recounting his visiting the Maharam Igra on Shmini Atzeres, who ate indoors as he was a member of the Lombardia family who had a minhag to do so. However, it is important to note that both Rashi (ibid.) and the Maharil (ad loc. Hilchos Sukkos s.v. b’leil Shmini) ruled and were particular to eat only in the Sukka on Shmini Atzeres.
 Although they do not rule this way, the Chayei Adam (vol. 2, 153:5), Aruch Hashulchan (Orach Chaim 668:3), and Maharsham (Daas Torah, Orach Chaim 668 s.v. chutz) cite minhagim to eat only partially in the Sukka. See also Shu”t Kiryas Chana Dovid (vol. 1, Orach Chaim 81), who writes that the inyan of Sukka on Shmini Atzeres is not a chiyuv but rather chavivus hamitzva.
 Korban Nesanel in his glosses to the Rosh (Sukka Ch. 4:7). An additional potential rationale (perhaps more of a limud zechus) for the widespread custom of eating indoors on Shmini Atzeres, is that many would flock to their Rebbe on Shmini Atzeres in accordance with the Talmudic dictum “Chayav adam lehakbil pnei rabbo b’regel” (Rosh Hashana 16b), and in the Sukka there was not enough room to contain the crowds. Due to overcrowding, people were mitzta’er and hence, pattur from needing to remain in the Sukka, and the gatherings eventually moved indoors. Once such a “minhag” was established, it was not long before people simply moved indoors for their seudos on Shmini Atzeres. See Shu”t Maharshag (ibid.), Moadim U’Zmanim (vol. 1:92), and Nefesh HaRav (pg. 220-221 s.v. inyan Sukka B’Shmini Atzeres). This understanding is a fulfillment of the Magen Avraham’s assessment (Orach Chaim 668:2), that “yeish k’tzas anashim hanohagim kach lefi shera’u kach mei’avoseihem.”
 Yechusei Tannaim V’Amoraim (Mossad Rav Kook expanded edition; pg. 328-330).
 Midrash Tanchuma (Parashas Pinchas, 15). The Hagahos on Rav Yitzchak Isaac Tirna (Tynau)’s Sefer Minhagim (Hilchos Shmini Atzeres 5) cites this as a potential reason why some would only partially eat in the Sukka on Shmini Atzeres, but in the following footnote, he nonetheless rules that on must eat all meals in the Sukka, even Seudas Shlishis if it fell on Shabbos, a psak later echoed by the Bach (Orach Chaim 668:1) and Magen Avraham (ad loc. 2).
 Yerushalmi Sukka (Ch. 4, Halacha 5), Pnei Moshe (ad loc. s.v. tzorech), and Targum Yonason / Yerushalmi (Parashas Pinchas, Bamidbar Ch. 29:35). On the other hand, these may not be such compelling proofs, as the Yerushalmi was written in Eretz Yisrael, as well as was where Rav Yonason ben Uziel lived, and in Eretz Yisrael there was no safek yom, just Acharon shel Chag (Simchas Torah). Indeed, the Elyah Rabba (668:2), citing the Amarcal, refers to those who eat indoors on Shmini Atzeres due to the Yerushalmi as exemplifying the pasuk in Koheles (Ch. 2:14) “ksil b’choshech holech,” as the Yerushalmi was not coming to argue on the Bavli’s psak, but rather was merely referring to Bnei Eretz Yisrael.
 See Netei Gavriel (Hilchos Arba Minim, Chelek HaShu”t 4, pg. 339-344) for an interesting historical ‘scorecard’ of sorts, listing which Gedolim and Admorim ate in the Sukka on Shmini Atzeres and which did not.
 Shu”t Chacham Tzvi (167) and Shulchan Aruch Harav (Orach Chaim 496:11; although he also cites that ‘yesh cholkim’, nonetheless, this first opinion is ikar - see also vol. 1, Mahadura Tinyana 68). This shittah is also defended by the Aderes (Sefer Shevach Ha’aretz, 35) and Shoel U’Meishiv (Shu”t Mahadura Telitai vol. 2:28), and heavily implied by the Avnei Nezer (Shu”t Orach Chaim 242:27 and 335:39: Hashmatos to Hilchos Yom Tov, 48-end; he maintains that ‘da’atam lachzor’ should not apply even for visitors from Eretz Yisrael who are staying in Chutz La’aretz over Yom Tov). This shittah has also found support in certain Rishonim, including Rabbeinu Chananel’s understanding of Rav Safra’s opinion (Pesachim 51b-52a), and the Ra’avan (Pesachim 162:2; see Even Shlomo’s commentary 37). Although, as shown later on, most contemporary authorities do not rule this way, nonetheless, many Chabad chassidim generally follow the shittah of their Alter Rebbe, the Shulchan Aruch Harav, and only keep one day in Eretz Yisrael, no matter how long they intend on staying. [However, there are those who cite different minhagim as prevalent in Chabad psak for this inyan. See, for example, Rav Levi Yitzchak Raskin’s extensive Kuntress Yom Tov Sheini, printed in his sefer Nesivim B’sdei HaShlichus vol. 1. Thanks are due to R’ Nochum Shmaryohu Zajac for pointing this out.] Rav Yechiel Michel Tukachinsky (Ir Hakodesh V’Hamikdash vol. 3, Ch. 19:8 and 11) reports that his grandfather-in-law, the Av Beis Din of Yerushalayim for the latter part of the nineteenth century, Rav Shmuel Salant, was notteh to this shittah as well. However, since he did not want to argue on his Rabbeim, including the Pe’as Hashulchan (see next footnote), who mandated visitors keeping Yom Tov Sheini, Rav Salant ruled that a Ben Chutz La’aretz should keep Yom Tov Sheini lechumrah, a shittah nowadays commonly referred to as ‘A Day and a Half’. This refers to being makpid on not doing any Melachah De’oraysa on the second day, but also not doing the unique Yom Tov Mitzvos, i.e. making Kiddush etc. Rav Avraham Yitzchak HaKohen Kook (Shu”t Orach Mishpat, Orach Chaim 125; thanks are due to Dr. Moshe Simon-Shoshan for pointing out this important source) and Rav Yosef Dov (JB) Soloveitchik (as cited inNefesh Harav pg. 84) were also known to be proponents of this shittah, reporting that this was also the preferred shittah of the Rav’s grandfather, Rav Chaim Soloveitchik of Brisk. [However, in this author’s opinion, the misnomer for this shittah, ‘A Day and a Half’ is somewhat troublesome. Anecdotally, years ago, I met an older relative here in Eretz Yisrael on Yom Tov Sheini and noticed that she was performing Melachah. When I asked her about it, she innocently replied that her Rabbi told her to keep ‘A Day and a Half’… and it was already after noon...] For more on Rav Shmuel Salant’s shittah, see the annual Tukachinsky Luach Eretz Yisrael (Chol Hamoed Sukkos, footnote), Shu”t Lehoros Nosson (vol. 11:26), Toras Rabbeinu Shmuel Salant (pg. 120), and Aderes Shmuel (Piskei Rav Shmuel Salant zt”l; Hilchos Yom Tov 129, and in footnotes at length, pg. 131-135).
 Although there are those who want to prove that the Shulchan Aruch meant to rule that a visitor to Eretz Yisrael should only keep one day, as in the Shulchan Aruch (Orach Chaim 496) he only mentions visitors from Eretz Yisrael in Chutz La’aretz, who need to keep a two-day Yom Tov like the locals [see, for example, Ir Hakodesh V’Hamikdash vol. 3, Ch. 19:11, in the parenthesis, as an additional sevara of Rav Shmuel Salant’s ‘libo amar lo efshar’… ], nevertheless, he personally put that notion to rest in his Shu”t Avkas Rochel (26), where Rav Karo explicitly ruled that the Yom Tov observance of visitors to Eretz Yisrael is dependant on whether they are planning on staying or not. [Indeed, in Ir HaKodesh V’Hamikdash Ch. 19:8, Rav Tukachinsky himself strongly disavows the aforementioned notion.] Other poskim who rule this way include the Rav Yaakov Emden (Shu”t Sheilas Ya’avetz vol. 1:168), the Pe’as Hashulchan (Hilchos Eretz Yisrael 2,15:21), the Chida (Shu”t Chaim Sha’al vol. 1:55, and Birkei Yosef, Orach Chaim 496:7), Mahar”i Chagiz (Shu”t Halachos Ketanos vol. 1:4; however, his son argues quite extensively, including psakim from his grandfather, Rav Moshe Galanti, and ‘Rabbanei Tzfas’, that Bochurim should certainly only keep one day), the Pri Ha’adamah (vol. 3, pg. 17b, and in Mizbach Adamah, Orach Chaim 468:4 s.v. ul’inyan; citing ‘kol Rabbanei Yerushalayim’ regarding a Bochur who plans on returning to Chutz La’aretz), Shaarei Teshuvah (Orach Chaim 496:3, in the parenthesis, and end 5; he makes a sikum of the shittos), Chayei Adam (vol. 2, 103:4), Aruch Hashulchan (Orach Chaim 496:end 5), Mishnah Berurah (ad loc. 13), Kaf Hachaim (ad loc. 38), and Rav Yechiel Michel Tukachinsky (Ir HaKodesh V’Hamikdash vol. 3, Ch. 19 8 and 11, and in his annual Luach Eretz Yisrael ibid.; although he does seem to give equal credence to his grandfather-in-law, Rav Shmuel Salant’s ‘Day and a Half’ psak). The vast majority of contemporary poskim rule this way as well. See Shu”t Igros Moshe (Orach Chaim vol. 3: 73 and 74 and vol. 4: 101), Orchos Rabbeinu (new print - 5775 edition, vol. 2, Ch. ‘Yom Tov Sheini’; citing the Chazon Ish and Steipler Gaon), Shu”t Seridei Aish (new edition; vol. 1, Orach Chaim 51:1), Shu”t Minchas Yitzchak (vol. 4:1-4), Yom Tov Sheini Kehilchaso (pg. 108, footnote 5; citing many Rabbanim including the Tchebiner Rav, Rav Shlomo Zalman Auerbach, Rav Yosef Shalom Elyashiv, and Rav Chaim Pinchas Scheinberg, whose teshuvah is printed in the back of the sefer), Shu”t Shevet Halevi (vol. 5:64), Shu”t Mishnah Halachos (vol. 4:83), Shu”t Tzitz Eliezer (vol. 9:30), Halichos Even Yisrael (Moadim vol. 1, pg. 287-288), Shu”t Yaskil Avdi (vol. 4, Orach Chaim 26), Shu”t B’tzeil Hachochmah (vol. 1:60), Shu”t Yabea Ome r (vol. 6, Orach Chaim 40:1-3), Shu”t Ohr L’Tzion (vol. 3, Ch. 23:5), Shu”t Knei Bosem (vol. 1:28), Chazon Ovadia (Yom Tov, pg. 133:12), and Yalkut Yosef (Moadim, pg. 460).
 Although many Rishonim each understand this Gemara differently, nonetheless, the Shulchan Aruch and other Acharonim, including the Radbaz (Shu”t vol. 4:73 or 1145; depending on edition), Magen Avraham (Orach Chaim 496:7), Shach (Yoreh Deah 214:8), and Pri Chodosh (Orach Chaim 466 and 468), follow the explanation of Tosafos, Rosh, and Ran (Pesachim ad loc.), that the defining factor is indeed ‘im da’atam lachzor.’
 How the poskim define ‘da’atam lachzor’ is not so simple and may vary from Posek to Posek and each individual situation needs to be taken into account. This was addressed at length in an article titled ‘One Day or Two? What is a Chutznik in Eretz Yisrael to Do?’
 Tukachinsky Luach Eretz Yisrael (Shmini Atzeres), Shu”t Minchas Shlomo (Kama vol. 1, 19:1 and Halichos Shlomo, Moadim vol. 1, Ch. 12:18), Shu”t Minchas Yitzchak (vol. 9:54), Shemiras Shabbos K’hilchasa (old print Ch. 31:40; new print Ch. 2:32 and footnote 65) and Netei Gavriel (Hilchos Arba Minim, Chelek HaShu”t 8; at length, and Hilchos Chag HaSukkos Ch. 87:14).
 Rav Moshe Feinstein’s shitta is found in Shu”t Rivevos Efraim (vol. 3:439). Shittos of Rav Yosef Shalom Elyashiv, Rav Shmuel Halevi Wosner, and Rav Chaim Pinchas Scheinberg are cited in Yom Tov Sheini K’Hilchaso (Ch. 2, footnote 48); Shu”t Ba’er Moshe (vol. 7, pg. 315:4 - Dinei Bnei E”Y & Chu"l). However, the Ba’er Moshe held that even though a Chutznik must eat in a Sukka in Eretz Yisrael on Shmini Atzeres, he nevertheless, need not sleep in the Sukka that night. However, the Steipler Gaon is quoted (in Yom Tov Sheini K’Hilchaso Ch. 2, footnote 49) as maintaining that a Chutznik should even sleep in the Sukka on Shmini Atzeres.
 The shitta of Rav Ben Tzion Abba Shaul is cited in Yom Tov Sheini K’Hilchaso (Ch. 2, footnote 49); Shu”t Yechaveh Daas (vol. 2:76); Shu”t Betzeil Hachochma (vol. 5:146). However, it should be noted that both Rav Shlomo Zalman Auerbach and Rav Yosef Shalom Elyashiv explicitly disagreed with this rationale. (See Yom Tov Sheini K’Hilchaso ibid.)
 Devarim (Ch. 14:1).
Disclaimer: This is not a comprehensive guide, rather a brief summary to raise awareness of the issues. In any real case one should ask a competent Halachic authority.
L'iluy Nishmas the Rosh HaYeshiva - Rav Chonoh Menachem Mendel ben R' Yechezkel Shraga, Rav Yaakov Yeshaya ben R' Boruch Yehuda, and l'zchus for Shira Yaffa bas Rochel Miriam and her children for a yeshua teikef u'miyad!