Lander College Model Beit Din 2017: Halacha and the International Date Line—TABC’s Fourth Consecutive Victory, Part One by Rabbi Chaim Jachter


Introduction: In Search of the Halachic date line

In 1941, hundreds of Yeshiva students from Mir and other European Yeshivot traveled to the Far East to escape Nazi persecution. Before reaching Shanghai, they temporarily settled in Kobe, on the Japanese island of Honshu. Realizing that they may have crossed the Halachic version of the International Date Line, many observed two days of Shabbat each week. The debate reached its crescendo in regard to the question of which day to fast on the Yom Kippur of that year.

During this challenging time, they corresponded with major Halachic authorities in Eretz Yisrael, hoping to determine the exact location of the Halachic date line. While the Encyclopedia Talmudit (22:665-694) presents no less than thirteen opinions regarding this issue, the most widely accepted views are those of the Chazon Ish, who places the line 90 degrees east of Jerusalem (longitude of 125 degrees east); Rav Yechiel Michel Tukitchinsky, who places the line 180 degrees from Jerusalem (longitude of 145 degrees west); and Rav Zvi Pesach Frank, who rules that Halachah accepts the legal international date line, located 180 degrees from Greenwich, England.

These three great authorities were contemporaries and were leaders regarding the debate as to the Halachic practice of the Yeshiva students in the Far East. Today, this fascinating debate has far-reaching ramifications, since travel to the Far East has become commonplace, and for some people, routine. Torah Academy of Bergen County participants in the Lander College Model Beit Din had to be prepared to analyze, debate, challenge, and defend these three formidable views. With Hashem’s help, they emerged as the victors for the fourth consecutive year.

The Chazon Ish’s Approach

A number of English-language articles present excellent summaries of this great debate. These articles include Rav Anthony Manning’s introduction to the issue of the international date line,[4] Rav David Pahmer’s essay,[5] and TABC alumnus Willie Roth’s 2005 essay written for Kol Torah.[6]

The two most prominent Rishonim who directly address this issue are Rav Yehudah HaLevi (Kuzari 2:20) and the Ba’al HaMa’or (Rosh HaShanah 5a in the pages of the Rif, s.v. Ki Salik), who state that the date line is located 90 degrees east of Jerusalem. The Ba’al HaMaor explains his position based on a passage that appears in Rosh Hashana 20b regarding the topic of Kiddush HaChodesh, the sanctification of the new month.

The Ba’al HaMa’or explains that Beit Din has until noon on the day they see the Molad, new moon, to declare Rosh Chodesh on that same day. However, if Beit Din’s announcement comes after noon, Rosh Chodesh is on the next day. The Ba’al HaMa’or reasons that in order for a day to be retroactively declared Rosh Chodesh in the middle of that day in Jerusalem, that same day must be beginning somewhere else in the world. At noon in Jerusalem—18 hours into the Jewish day, starting from sunset—the sun is setting and the Jewish day beginning 18 hours west of Jerusalem, which is 270 degrees west of Jerusalem, or 90 degrees east of Jerusalem, since every hourly time zone is 15 degrees wide. Therefore, writes the Ba’al HaMa’or, the Halachic Date Line must be at the “Ketzei HaMizrach” (literally “eastern edge”), 90 degrees east of Jerusalem.

The Chazon Ish bases his ruling primarily on this assertion of the Kuzari and the Ba’al HaMa’or.[7] It is important to note, though, that many Rishonim, including both Rashi (Rosh HaShanah 20b s.v. Nolad Kodem Chatzot) and Tosafot (op. cit. s.v. Chatzot), do not agree with the Kuzari’s and Ba’al HaMaor’s interpretation of Rosh HaShanah 20b. The Chazon Ish argues that while Rashi and Tosafot reject the Kuzari’s and Ba’al HaMa’or’s interpretation of Rosh HaShanah 20b, Rashi and Tosafot do agree with the assertion that the Halachic date line lies 90 degrees east of Jerusalem. The Chazon Ish argues that this view is an undisputed Mesorah (tradition) from ancient times.

Rav Yechiel Michel Tukachinsky’s 180-Degree Opinion

Rav Yechiel Michel Tukachinsky composed an entire treatise on the subject of the Halachic date line entitled HaYomam BeKadur HaAretz. His 180-degree opinion is based on Yechezkeil 38:12, which describes Eretz Yisrael/Yerushalayim as “Tabur HaAretz,” the center of the world. Radak to this Pasuk translates the phrase “Tabur HaAretz” as “stomach of the land”; Israel lies in the middle of the world, just as the stomach lies in the middle of the body.  

Rav Tukachinsky’s Logic

Rav Tukachinsky and the Chazon Ish engaged in a ferocious and extended battle of arguments both in writing and in person. We present some of the highlights of their arguments in order to allow our readers to sense the intensity of this classic debate. Rav Tukachinsky argues that just as there must be a date line, there must be a center from which the date line measures. Rav Tukachinsky views it as intuitive and obvious (without a need to cite explicit sources from Chazal) that Jerusalem should be the prime meridian and that 180 degrees from Jerusalem is the anti-meridian/date line.

Moreover, he finds it highly counterintuitive to divide the world 90 degrees east of Jerusalem and 270 degrees west of Jerusalem. He cites the Talmud Yerushalmi (Rosh Hashanah 2:4) as support. The Yerushalmi states that there are 365 “windows” (Rav Tukachinsky understands this as the rough equivalent of what we call “degrees”), of which 182 are in the east, 182 are in the west, and one is in the middle.

Rav Yechiel Michel supports his view from a Sefer written by a Rishon, the Yesod Olam (2:17), which dismisses 90 degrees east of Jerusalem as the date line. The Yesod Olam argues that if this was the date line, it would cut through land and would lead to the absurdity of it being one day on one side of a street and another day on the other side of the street. For example, it would intersect Dongfeng Street in Changchun, China. Families on the eastern strip of Dongfeng Street would recite Kiddush while families a block to the west would recite Havdalah. It may be possible for those who want two days of Shabbat to walk one block eastbound down Dongfeng Street after Seudah Shlishit and start Shabbat again. Those who want to skip almost all of Shabbat could take a short stroll westbound and go from sunset Friday to sunset Saturday. The Yesod Olam argues that the Halachah does not tolerate such a situation.

Rav Tukachinsky believes that the Yesod Olam rejects the Ba’al HaMa’or/Kuzari approach, opening the possibility of an alternative, namely 180 degrees from Jerusalem. This date line does not, for the most part, run through land (Alaska is a major exception), thereby avoiding the Yesod Olam’s concern.

The Chazon Ish, however, believes that the Yesod Olam accepts the view that the date line runs 90 degrees east of Jerusalem. Yesod Olam, in the Chazon Ish’s view, merely bends the date line from 90 degrees east to the eastern coasts of Siberia, China, and Australia, where the line would otherwise have crossed land. The Chazon Ish views the sea-coast as an intuitive and plausible border for the date line. Rav Tukachinsky dismisses the Chazon Ish’s bending of the date line to the eastern edges of Siberia, China, and Australia as artificial and baseless.

Rav Yechiel Michel understands Rashi’s alternative approach to Rosh Hashanah 20b as rejecting the Kuzari/Ba’al HaMa’or approach. He notes many Rishonim who explain Rosh HaShanah 20b differently than the Ba’al HaMa’or/Kuzari and who must therefore reject 90 degrees from Jerusalem as the date line.

Rav Tukachinsky understands the Ba’al HaMa’or and Kuzari as holding their opinion only at a time when known human habitation was limited to the “Old World” of Europe, Asia, and Africa. Since only half of the globe was known to be populated, it made sense for the date line to lie at the end of the inhabited portion of the world (i.e. 90 degrees from Jerusalem). He argues that in modern times, when all of the earth is inhabited, the entire globe must be considered when establishing the date line (i.e. 180 degrees from Jerusalem).

Rav Tukachinsky concludes “Jerusalem is our Greenwich,” and thus, since Jerusalem is the Halachic prime meridian, the Halachic date line must be 180 degrees from it. He wonders what the Halachic significance of China could possibly be for the date line to run through it, and he wonders why 180 degrees from China could possibly serve as the Halachic prime meridian.

Alaska poses a difficulty to Rav Tukachinsky—his approach follows the Yesod Olam’s avoidance of the date line running through a community and therefore prefers the date line to run through the sea. However, the 180-degree line runs through the middle of Alaska. Rav Yechiel Michel suggests the date line would run along the western Alaskan coast.  

It is significant to note that Rav Yosef Eliyahu Henkin (Eidut LeYisrael p.119) rules in accordance with Rav Tukachinsky.  


Next week, we will iy”H conclude our review of the debate concerning the Halachic date line with a summary of the Chazon Ish’s response to Rav Tukachinsky’s assertions.

[4] Rabbi Manning’s essay is accessible at


[5] Rav Pahmer’s essay may be found in the Journal of Halacha and Contemporary Society number XXI

[6] Willie Roth’s essay may be accessed at


[7] The Chazon Ish presents his opinion in his Kuntruss Yud Chet Sha’ot, which is included in his commentary on the Orach Chayim section of the Shulchan Aruch.

Lander College Model Beit Din 2017: Halachah and the International Date Line—TABC’s Fourth Consecutive Victory, Part Two by Rabbi Chaim Jachter

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