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A Traveler's Guide To The International Dateline
Rabbi Dovid Heber, Star-K Kashrus Administrator
Summer 2012

In today's global market, the furthest regions of the Earth are much closer to home than one could ever imagine.  For example, citric acid – an integral ingredient in soft drinks, ascorbic acid (vitamin C) – a common nutrient, and amino acids used in numerous food items, are produced in a variety of Star-K certified Chinese plants.  Star-K certified glycerine is manufactured in the Philippines and shipped to the United States.  Mashgichim are frequently sent to Thailand, Fiji, Vietnam, and Indonesia to oversee production of kosher spices, tuna fish, and canned fruits and vegetables.  The Star-K has an office in Shanghai to administer the supervision and inspect facilities.

When assigning a mashgiach from the United States to inspect these factories, besides briefing the mashgiach on ingredients, equipment, and products at the plant, the halachic issues of crossing the International Dateline often must be addressed.  This issue is not unique to mashgichim.  Tourists and business travelers flying to the Far East and South Pacific regions, as well as Hawaii and Alaska, are confronted with such shailos on a regular basis.

What is the International Dateline?  The International Dateline accepted worldwide (hereafter referred to as the Civil Dateline) is an imaginary line zig-zagging around 180° longitude through the Pacific Ocean (see attached map), separating one day from the other.  If it is 1:00 p.m. Monday on the eastern side of the Dateline, it is 1:00 p.m. Tuesday on the western side.1  Therefore, if one travels from the United States to China, a day is "lost".  For example, if one crosses at noon Monday, one would turn his watch (with date display) ahead from noon Monday to noon Tuesday as he crosses the line traveling westbound, "skipping" Monday afternoon and night, and Tuesday morning.  When one travels from China to the United States, a day is "gained," as one would turn his watch back from noon Tuesday to noon Monday.  This person will experience Monday afternoon and night, as well as Tuesday morning, twice.

Halacha addresses two aspects of the Dateline:  The location and halachic implications of crossing the Dateline.

I. Location: Various Rishonim, early commentators, and many Acharonim, later commentators, have written extensively on this topic.  The three major opinions are as follows:

A. The Chazon Ish2 bases his opinion on the Baal Hamaor's explanation of a gemara in Rosh Hashana.3  The Dateline "technically" runs 90 degrees east of Yerushalayim,4 where the time is six hours later. This line is at 125.2°E and runs through Australia, the Philippines, China, North Korea and Russia.

However, if this was the Dateline it would cut through land.  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 havdala.  It may be possible for those who want two days of Shabbos to walk one block eastbound, down Dongfeng Street, after Seuda Shlishis and start Shabbos again.  Those who want to skip almost all of Shabbos could take a short stroll westbound, and go from sunset Friday to sunset Saturday.  However, halacha does not allow for such a situation. Instead, we consider the eastern land masses tafel (secondary) to the western land masses of these same continents.  Therefore, eastern landmasses of Asia and Australia observe the same day for Shabbos as the western sections.  This is known as graira.5

Therefore, the halachic Dateline of the Chazon Ish avoids going through land by gerrymandering along the Asian coast (see map), then along the 125.2°E longitude line, through the East China Sea, Philippines, and Indonesia.  Finally, the line cuts eastward, around most of the northern, eastern and southern coasts of Australia, and then at 125.2o E turns south towards Antarctica.  According to the Chazon Ish, Japan, New Zealand, Tasmania, and Fiji are on the same side of the Dateline as the United States.  When the Japanese and New Zealand residents say it is Saturday, halacha says it is Friday.  When they say it is Sunday, it is halachically Shabbos.  This would also apply to parts of Indonesia and the Philippines.

B. Rav Yechiel Michel Tukatzinsky, zt”l,6 bases his ruling on Chazal's Judaic principle that Yerushalayim is "the center of the world."  If so, the Earth "starts and ends" (i.e. the Dateline) on the exact opposite side of the Earth, halfway around the globe at 144.8°W. This line runs from the Gulf of Alaska through the Pacific Ocean east of Hawaii, placing the entire state of Hawaii on the "other side of the Dateline" from the United States.  Hawaii would then be nineteen hours ahead of Baltimore, rather than five hours behind, as it is on the same side of the Dateline as Asia.  The day Hawaiians call Friday is halachically Shabbos, and the day they call Saturday is halachically Sunday.7

C. "Mid-Pacific Poskim" - Several Poskim, including the Bnai Tzion,8 are of the opinion that the halachic Dateline runs through the middle of the Pacific Ocean and closely resembles the Civil Dateline.  According to these opinions, Japan and New Zealand are on the western side of the Dateline (similar to Asia), and residents of these locations observe Shabbos on the local Saturday.  Hawaii is on the eastern side of the Dateline (similar to America), and residents observe Shabbos on their local Saturday.

The exact location varies among the Mid-Pacific Poskim.  The Bnai Tzion's Dateline slants westward through the Bering Straits (between Alaska and Siberia), touching the Siberian coast, through the Pacific Ocean at approximately 177°E (west of Fiji), then turns east of New Zealand.  Other Mid-Pacific Poskim, including Rabbi B. Rabinowitz Thumim,9 Atzei Sodeh10 and Alai Yonah are of the opinion that the line is at 169.7°W - from the eastern tip of Siberia, directly southward through the Pacific Ocean, 10° east of the Civil Dateline.11

What is the Halacha?  One should consult with his Rav prior to crossing the Pacific Ocean, especially if he must stay over Shabbos in Japan, New Zealand, or Hawaii.  The halachic ruling of HaRav Moshe Heinemann, shlit"a, Rabbinic Administrator of the Star-K, is as follows:  One should follow the majority of opinions (as listed in sections A, B and C above) in determining which day is observed as Shabbos, and also observe dinei d’Oraisa shel Shabbos, Shabbos prohibitions of the Torah, on the day of the minority opinion.  However, Rabbinic prohibitions, such as shopping and the handling of muktzah, are permissible on the day which the minority opinion considers Shabbos.  In addition, performing even a biblically prescribed violation of Shabbos through a shinui, unusual manner, or through the action of a non-Jew, would be permitted on the day which the minority opinion considers Shabbos.

The halachic ramifications of this psak are as follows:  In New Zealand and Japan, "Saturday" is Shabbos according to Reb Yechiel Michel Tukatzinsky and the Mid-Pacific Poskim.  Therefore, the local Saturday should be fully observed as Shabbos, with tefilos Shabbos and kiddush, etc.  However, according to the Chazon Ish, Shabbos is on the local Sunday.  Therefore, one should not perform any melacha d’Oraisa on Sunday.  Nevertheless, on Sunday, one should daven regular weekday tefillos, donning tefillin during Shacharis.

In Hawaii, "Saturday" is Shabbos according to the Chazon Ish and the Mid-Pacific Poskim.  Therefore, the local Saturday is fully observed as Shabbos.  The day known locally as "Friday" is Shabbos according to Reb Yechiel Michel Tukatzinsky, and one should not perform melacha d’Oraisa on that day.  Cooking for Shabbos should be done on Thursday.  On Friday, when preparing for “Shabbos”, one may turn on hot water, electricity or fire (e.g. to cook) with a shinui.  To light Shabbos candles, using one’s elbow or chin (a shinui), turn on two flashlights12 that use incandescent bulbs13 and then recite the brocha.

Determining the majority opinion on the Aleutian Islands or South Pacific Islands, including Fiji, American Samoa, and Samoa,14 is complicated and details are beyond the scope of this article.  Consult a Rav.  However, in the following locations, Shabbos is observed on the local Saturday, and a "second day" is not necessary:  Australia, China, Russia, and Korea.15  This is also the case in Hong Kong and Taiwan.

II. Crossing the Dateline:  Repeating or skipping a day by crossing the Dateline poses various concerns in many aspects of halacha, including davening, sefira, holidays, and laws of family purity.  The guidelines are as follows:  Halachos relating specifically to the time of day are not affected by crossing the Dateline.  For example, if one davens Shacharis on Monday morning on a plane flying westbound, and crosses the Dateline "into" Tuesday morning, one does not daven Shacharis again.16  The person has already fulfilled his obligation and is not required to perform these mitzvos until the sun sets and rises again.  Furthermore, if one crosses eastbound and experiences an additional sunrise, one would daven Shacharis again, even if the day is repeated.17  However, mitzvos that are dependent on the day of the week or month are affected by crossing the Dateline.  For example, if one crosses the line westbound from 1:00 p.m. Thursday to 1:00 p.m. Friday, one must begin preparing for Shabbos as it is Erev Shabbos and Shabbos will begin in several hours.  If one flies westbound from 1:00 p.m. on Monday, the 16th of Tammuz, and crosses the halachic Dateline to 1:00 p.m. Tuesday on the 17th of Tammuz, one fasts until nightfall.18

III. Sample Itineraries:

A. Westbound - "Lose a Day" - Qantas Airlines Flight #12
Leave Los Angeles 10:10 p.m. Sunday - Arrive Sydney 6:10 a.m. Tuesday

Except for the end of the flight, this 15 hour flight is through the night.  One davens Maariv in Los Angeles.  After crossing the Dateline, an additional Maariv is not required, even though it instantaneously becomes the next night.19  If Sunday night is 32 b'omer, and one counts sefira in Los Angeles, when crossing the Dateline one counts 33 b'omer without a brocha and then again counts 33 b’omer without a brocha upon landing in Sydney on Tuesday morning. On Tuesday night, 34 b'omer, and on the remaining nights of sefira, a brocha is recited.20  On Chanukah, if one lights three Chanukah candles on Sunday night, before leaving Los Angeles, one lights five candles on Tuesday night in Sydney.  The fourth night is "skipped".  If a hefsek tahara was performed on the previous Shabbos afternoon, Sunday is Day #1 of the shiva n'kiim, Monday is skipped, Tuesday is Day #2, etc. Sunday is Day #7, and one goes to the mikvah on Sunday night.21  Shabbos and Yom Tov22 are on the same day on which the Australians keep it.23 

B. Eastbound - "Gain a Day" - United Airlines Flight #896
Leave Hong Kong 11:10 a.m. Tuesday - Arrive Chicago 12:50 p.m. Tuesday

The sun sets several hours into this 13 hour flight.  It then rises several hours later. One davens Tuesday's Mincha two hours after take-off, Maariv after nightfall, and Shacharis after sunrise.  Although the Dateline has been crossed before sunrise, and it is Tuesday morning again, one davens the Tuesday Shacharis on the plane and Tuesday Mincha in Chicago.  One davens all three tefilos twice on Tuesday since these laws are governed by cycles of sunrise and sunset, not days of the week.24  If Tuesday is 33 b'omer, 33 b'omer is counted on Monday night in Hong Kong.  After landing in Chicago on Tuesday, 33 b'omer is counted again without a brachaOn Tuesday night, 34 b'omer, and on the remaining nights of sefira, a bracha is recited.25  If Tuesday is the third day of Chanukah, three candles are lit on Monday night in Hong Kong and four candles on Tuesday night in Chicago. Hallel is recited nine times, as one davens Shacharis on Tuesday morning (the third day of Chanukah) twice.  In this case, if a woman made a hefsek tahara on Sunday afternoon in Hong Kong, and crossed the Dateline during the Shiva Neki’im, she could go to the mikvah on Motzai Shabbos, as she has experienced seven days and seven nights.26

One should preferably not depart Sydney, Hong Kong or Shanghai going east over the Pacific on Sunday as, according to the Chazon Ish, it is Shabbos shortly after take-off, when the plane begins flying northeast over the Pacific Ocean.  B’shaas hadchak (if very necessary), if one flies on Sunday, one should not do any melacha d'Oraisa until nightfall.  Similarly, it is preferable that one should not depart from these locations (to fly east toward America) on Friday.  B’shaas hadchak, if one departs on Friday,27 one must take off well before sunset (to avoid issues of t’chum Shabbos) and keep Shabbos from sunset until crossing 144.8°W longitude, when it is Friday again according to all opinions, including Reb Yechiel Michel Tucatzinsky.28

In the summer of 1894, the Rav of Melbourne, Rav Avraham Abir Hirschwitz, traveled by ship from Sydney to Auckland, New Zealand, and San Francisco.  The details of his trip and psak were published in 1908 in his sefer, Shailos U' Teshuvos Beis Avrohom. Perhaps at the time, those studying this sefer thought this was halacha she'aino nogaya l'maaseh, non-practical, non-relevant law.  Little did they realize that one hundred years later, Jews from all over the world would fly this route on a regular basis, and the laws would become more relevant than they could ever imagine.


The author wishes to thank Rabbi S.D. Siegel, author of Atzei Sodeh, Rabbi Yisroel Taplin, author of Sefer Taarich Yisroel, and Mr. Chaim Brumer for their invaluable assistance in preparing the original article on this topic, published in 1997.  Special thanks to R’ Eliyahu Hershfeld for his assistance and for providing the map, as found at www.kosherjava.com/2012/03/25/the-halachic-date-line-map/.  For a detailed discussion in English on this topic, see “The Dateline in Halacha” by Rabbi Zalman Tropper.

1. In reality, there are locations whose times differ by 25 and even 26 hours.  When it is 12:01 a.m. Tuesday on Kiritimati Island, in the easternmost time zone of the world, it is 12:01 a.m. Monday – 24 hours earlier in Honolulu (which is directly north); in Pago Pago, American Samoa it is 11:01 p.m. on Sunday night.  In the uninhabited shipping regions just east of the Dateline, and on Howland & Baker Islands, it is 10:01 p.m. on Sunday night – 26 hours behind Kiritimati.

2. In Kunteres Yud Ches Sha’os.  This is also the opinion of the Kuzari (2:19-20) and various other Rishonim.

3. Rosh Hashanah 20b, which discusses the appearance of the new moon in different regions of the world.

4. The Kodesh Hakadashim, on the Har Habayis, was located at or near 35o 14’ 07”E longitude and 31o 46’ 41”N latitude.  The Baal Hamaor’s line would be 90o east of this longitudinal line.  See Sefer Shaarei Zmanim, Siman 4 Footnote 2, as to how the exact location of the Har Habayis impacts on understanding the time of the molad and Kiddush Levana.

5. This is based on the Yesod Olam, Rav Yitzchok Yisraeli, a talmid of the Rosh.  For a full discussion of graira and those who disagree with this concept, see Sefer Taarich Yisroel 1:4-8, and and 1:14.

6. The author of the Gesher Hachaim, in Sefer Hayomam B'Kadur Ha'aretz. Harav Henken, zt”l, has a similar opinion in Edus L’Yisroel page 119.

7. According to this opinion, the Aleutian Islands of Alaska are on the western side of the dateline. Whether this opinion holds of graira is a safek and, in turn, there is a machlokes haposkim.  If graira is said, then all of mainland Alaska is the same day as the rest of America.  According to the opinion that graira is not said, the line runs through the city of Central, AK and, therefore, most of Alaska – including Anchorage and Fairbanks – are on the western side of the Dateline.  However, either way, Juneau is on the eastern side and the same day of the week as the Lower 48 states.  For a full discussion, see Sefer Taarich Yisroel 1:15.  In Alaska, there are additional halachic concerns above the Arctic Circle (where it can be 24 hours day or night).  For a full discussion, see Sefer Shaarei Zemanim Siman 11 and  "When Does One Pray When There Is No Day" in Kashrus Kurrents, Summer 2007.

8. Rav Dovid Shapiro in Shaalos U’teshuvos Bnai Tzion 2:10.

9. In Hapardes Iyar 5714.

10. Rabbi Shmuel Dovid Siegel

11. For a full discussion of additional opinions, including those who hold that one follows the local tradition and other similar opinions, see Sefer Taarich Yisroel 1:11-12.

12. One may use one flashlight, if that is all that is available.

13. One may not use a fluorescent or LED light, as they are not considered a ner (candle), even though they may be aish (fire).

14. L’halacha, one keeps 49 hours of Shabbos every weekend, due to this safek.  At the end of 2011, Samoa “skipped” the entire Friday, December 30 by turning their clocks ahead 24 hours in order to switch from the eastern side of the dateline to the western side (i.e. the same day as New Zealand).  Therefore, any Yid there should have kept Shabbos from sunset on Thursday, until it became dark on Sunday night (49 hours later).

15. The above is true if land is attached to the Asian or Australian continent.  Islands may have a different status, depending upon their location. 

16. One should, however, recite the Yom for Tuesday.

17. This is similar to the opinion of the Tshuvos Betzel Hachochma (5:103) written by Harav Betzalel Stern.  See Sefer Taarich Yisroel 4:2, that this is also the opinion of Harav Y.S. Eliashiv shlita.  It should be noted that the Sefer Emek Hateshuva (2:6), written by Harav Yechezkel Roth, disagrees and is of the opinion that one davens based on the date.  For example, according to this opinion, if one flies west at night and crosses the dateline, one should daven maariv again.  If one flies eastbound over the dateline and repeats a day, one need not daven again, despite the sunset and sunrise.  Rabbi Yisroel Taplin suggests a “compromise” between both opinions is to daven Shemoneh Esrei with a “t’nai nedava” (i.e. one says “This Shemona Esrei is a nedava [gift] if I am not obligated”, etc.) going in either direction.  For a full explanation of this opinion, see Taarich Yisroel (4:15 & 20).  This compromise is a “hiddur”.  L’halacha l’maase, Rav Moshe Heinemann holds that one can follow the opinion of the Betzel Hachochma, as noted above.

18. See Sefer Yisroel V’hazmanim, Siman 79.

19. See Footnote 17.

20. Sefer Yisroel V’hazemanim, Siman 79.  He also notes that Shavuos is celebrated on the same day as the locals.

21. See Footnote 26.

22. Including Shavuos.

23. The following westbound flight poses a fascinating shaila.  China Airlines Flight #5 in the winter, leaves Los Angeles at 1:55 p.m. on Friday, arriving in Taipei, Taiwan on Motzai Shabbos at 8:35 p.m.  On this flight, one departs on Friday afternoon and lands Motzai Shabbos!  When the sun goes down, or when one crosses the Dateline, whichever comes first, it is Shabbos at 37,000 feet for several hours, until one crosses the dateline into “Motzai Shabbos” or it gets dark.  If a person is not mechalel Shabbos on the plane, since he does not take off or land on Shabbos, there are svaros to be matir this flight.   Nonetheless, the consensus of the poskim is to avoid taking this flight and skipping most of Shabbos    (see Igros Moshe O.C. 3:96).

One need not cross the International Dateline to have this shaala. For example, if one flies Air India Flight #102 on a Friday in late November or early December, one would take off at 2:25 pm on Erev Shabbos two hours before sunset and land in Mumbai, India at 6:55 pm on Motzai Shabbos, shortly after tzais hakochavim. One would experience the entire Shabbos onboard without taking off or landing on Shabbos. Shabbos would begin about an hour after takeoff (candle lighting time/before sunset) and the sun would rise Shabbos morning about 9 hours later. The entire Shabbos day would go by relatively quickly with sunset (6:00 pm Mumbai time) and tzais hakochavim occurring shortly before landing at 6:55 pm. Once again, the consensus of the Poskim is not to take such a flight.

24. See Footnote 17.

25. See Footnote 20.

26. This is based on the explanation above, in Section II “Crossing The Dateline”.  See Tshuvos L’Horos Nosson 11:6:7.    

27. Sefer Taarich Yisroel 21:15 quotes several poskim, including Rav Eliashiv shlita, who holds this is permissible in order to be home with one’s family for Shabbos.

28. Once one reaches 169o W, one may perform issurei d’rabanan but should refrain from d’Oraisas until reaching 144.8oW or mainland Alaska. 




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