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December 10, 2024
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Rav Mordechai Kuber’s ‘Crossing the Dateline’: The International Dateline Halachic Issues Finally Clarified

Part II

Location of the Halachic Dateline: Sephardic and Chabad Approaches

Last week we introduced Rav Mordechai Kuber’s spectacular new three-volume collection titled “Crossing the Dateline,” the authoritative sefer on the halachic ramifications of the International Dateline (IDL). Together with more than 30 TABC students, we devoted our recent intersession to delving into this magnificent sefer capped by hearing directly from Rav Kuber via Zoom.

Volume one presents the great debate surrounding the location of the dateline. Rav Kuber states that a halachic consensus has emerged supporting the opinion that the halachic dateline lies 180 degrees from Jerusalem. Accordingly, baseline halacha requires observance in Japan and New Zealand on Saturday, but Shabbat’s fulfillment on Friday in Hawaii and most of Alaska.

The Star-K posts a magnificent map that very clearly outlines the issues. https://www.star-k.org/articles/wp-content/uploads/2015/12/IDL_Map.pdf

However, the Sephardic and Chabad approaches differ. Yalkut Yosef Orach Chaim 37:10 indicates that Rav Ovadia Yosef believes that the halacha follows the civil dateline, and Rav Gavriel Elbaz confirmed that this is the opinion of Rav Ovadia Yosef. Rav Shlomo Amar told me that this is his opinion as well. Similarly, the Chabad communities in Japan, New Zealand, Alaska, and Hawaii all observe Shabbat on Saturday of their respective locations. The Lubavitcher Rebbe was in good health for at least four years when Chabad Houses were already following this practice.

Anyone traveling to these areas should consult their rabbi for guidance. Many rabbanim will advise travelers to follow the 180 line or the IDL but refrain from Torah prohibitions on Shabbat according to the other opinions. Some rabbis even recommend avoiding being in these areas near and on Shabbat unless it is essential. Rav Kuber, in volume three of his monumental work, provides detailed guidance to those who wish to accommodate all opinions while traveling in the disputed zones.

Crossing the Dateline Westbound to ‘Tomorrow’

Volume two tackles the issues involved when crossing the dateline westbound into “tomorrow” and eastbound into “yesterday.” In other words, when crossing the dateline heading west, one enters the next day, but when traversing this boundary heading east, one leaps back into the previous day. I will relate how I handled this issue while traveling back and forth with my wife to Hong Kong in 1998.

We left Newark airport Sunday morning and expected to cross the dateline at about 3 p.m. that afternoon. I made sure to pray Sunday afternoon’s Mincha before crossing the 180-degree line to the west. After crossing the IDL, I placed tefillin and prayed Mincha for Monday afternoon. While Rav Kuber sets forth the many opinions regarding this matter, I followed Rav Ovadia Yosef (Yalkut Yosef Orach Chaim 37:10) and Rav Herschel Schachter. They believe that crossing the dateline to the west terminated my Sunday afternoon’s obligations and triggered my Monday afternoon responsibilities.

Their ruling is based on the Gemara (Shabbat 118b), which praises those who begin Shabbat in Tiberius and those who end Shabbat in Tzippori. Rashi (ad. loc. s.v. MiMachnisei) explains that Tiberius lies on a low altitude, and thus the sun appears to set early there, leading its residents to begin Shabbat early. Tzippori, on the other hand, rests on a mountain where the sun seems to set late, and its residents, therefore, observe Shabbat until quite late.

Rav Akiva Eiger (Gilyon HaShas ad. loc.) cites a responsum of the Ri Migash (45), who explains that the praise refers specifically to those who begin Shabbat in Tiberius and walk on Shabbat to Tzippori to complete Shabbat there. The people who begin Shabbat in Tiberius and end it in Tzippori deserve praise because they place themselves in a situation in which they are obligated to observe Shabbat longer.

This interpretation of the Gemara teaches that even if one is a resident of Tzippori but finds himself in Tiberius on Friday evening, he must accept Shabbat when it begins in Tiberius even though it has not yet commenced in Tzippori. Similarly, a resident of Tiberius located in Tzippori must wait until Tzeit HaKochavim in Tzippori to end Shabbat even though Shabbat already has finished in Tiberius.

Thus, one’s real-time location determines one’s halachic obligations and not his usual place of residence. Chacham Ovadia and Rav Schachter believe that one’s duties in the air are the same as if one is located on the land or sea below. They both also believe that there is no difference between land and sea regarding crossing the dateline.

Next week we shall conclude our review of the halacha and the IDL with a discussion of when crossing the IDL to the east.


Rabbi Haim Jachter is the spiritual leader of Congregation Shaarei Orah, the Sephardic Congregation of Teaneck. He also serves as a rebbe at Torah Academy of Bergen County and a dayan on the Beth Din of Elizabeth.

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