Six days work may be done but the seventh day is Shabbat, a holy time, during which you shall not work. It is to be a day of Shabbat unto Hashem in all of your settlements.

(Vayikra 23:3)

Adam, the first human being, observed the first Shabbat wherever he happened to be. His Shabbat began when the sun set in his vicinity. Yet at that very moment, elsewhere around the globe, it could have been morning or any other time of day, depending upon the longitude. While for him the sun was setting, at Adam's antipode day was breaking. If so, one might suppose that Shabbat should begin at different times of the day in different parts of the world. This, says the Sforno, is why the Torah wrote the phrase, "in all of your settlements." The Torah is informing us that in every Jewish settlement, on every part of the globe, Shabbat should be one full day and it should begin at sunset, local time. (NOTE: Halachically, the day is defined as beginning and ending at sunset.)

Radbaz (Spain, 14th cent.) deals with this question in his reponsa (1:76). He does not make reference to the verse cited by the Sforno but rather to a verse in Shemot. His explanation has even more interesting implications.

In Shemot (31:13), Hashem tells us, "Keep my Shabbat because it is a *sign* between me and you throughout the generations." Shabbat is a sign of Hashem's closeness to His people. There is another Mitzvah which is referred to as a "sign," and that is the Mitzvah of circumcision. Radbaz suggests that just as the circumcision is a personal covenant between the individual and Hashem so, too, should each Jew see the Shabbat as his or her *personal* covenant with Hashem rather than viewing the Shabbat as a covenant between Hashem and the Jewish People as a whole. Therefore, Radbaz concludes, each person is to observe the Shabbat wherever he may be according to his own longitude and latitude. It makes no difference at all that Jews elsewhere are observing the Shabbat during different hours. (Radbaz points out that the same logic may be followed concerning the Jewish holidays and Yom Kippur. [They, too, are referred to as "signs" -- see Menachot 36b. -MK])

Radbaz insists further, that the observance of Shabbat is not confined to a single day of the week. The Mitzvah of the Torah is simply to observe any one day out of seven as a Shabbat. No matter where a person is in the world, he is fulfilling the will of the Torah by observing Shabbat one day out of seven. Radbaz cites a number of proofs to support this startling position.

Firstly, he quotes a Gemara (Shabbat 69b) which tells us, "If one is traveling in the desert and he forgets which day is Shabbat, he should count six days and keep the seventh day as Shabbat." We see from here, says Radbaz, that observing any one day out of seven as the Shabbat is tantamount to observing the Shabbat.

Similarly, Radbaz quotes a passage in Sanhedrin (58b) which says that a gentile is prohibited from observing the Shabbat because it is a private covenant between Hashem and the Jewish people. The Gemara adds that it is even prohibited for the gentile to make himself a Shabbat on a Monday or Tuesday. Why, asks Radbaz, should it be forbidden for the gentile to keep a different day of the week as his Shabbat? After all, this should not be considered an infringement upon the covenant that God made with the Jewish People, which was to observe the *real* day of Shabbat! Apparently, keeping any one day out of seven is already an infringement on the covenant.

(It is interesting to note that Rashi (loc. cit.) seems to understand both Gemarot differently than Radbaz. According to Rashi's understanding there is absolutely no proof from these passages to Radbaz's principle. Note, too, that the Gemara in Sanhedrin 65b seems to clearly accept that Shabbat is a universal, absolute time-period and not an arbitrary seventh day. -MK)

Radbaz suggests an interesting rationale for his principle. Hashem gave the Mitzvah of Shabbat specifically in this "personal" manner because He knew that eventually the Jews would go into exile and that they would be scattered to the most remote areas of the globe. Since it would be impractical to keep the Shabbat based upon a different time zone, Hashem instructed that the Shabbat be kept privately by each individual, wherever he may be.

One should not reach the mistaken conclusion that, according to Radbaz, everyone can choose his own day of the week to observe as Shabbat. Radbaz himself takes pains to exclude such a possibility. Rather, Radbaz proves that we must accept one of two possible guidelines:

1. One must observe the same Shabbat as everyone else in his region (= longitude?).

2. One's personal Shabbat must overlap with "universal" Shabbat. When the sun is crossing the Pacific Ocean, all of Eurasia (and the Americas) are observing Shabbat. Therefore every Jew, no matter where in the world he lives, must be arrange that his Shabbat day include these hours as well.

First, let us understand why it is necessary to establish a dateline in the first place. Imagine for a moment an earth that does not rotate on its axis. It always presents the same face to the sun and those who live on that face experience a never-ending day. Now imagine that you are traveling around that earth from west to east. As you move further towards the east, you put the sphere of the earth between you and the sun. The sun moves closer to the horizon until it sets behind you in the west. As you round the earth and begin heading towards the sun again, the sun eventually rises before you, over the eastern horizon. You have created an "artificial day" of your own, without resorting to the earth's rotation!

If, during your journey, the earth was rotating as well, the two rotations (yours and the earth's) would have a cumulative effect. Thus, if you were to complete your journey eastward during the course of seven 24-hour periods, everyone else on earth will have experienced seven days while you will have experienced eight! You will return home to find your hometown observing the Shabbat, while for you it will already be Sunday! The same exact situation arises in reverse when traveling around the globe from east to west. The traveler "loses" one day.

In order to correct this absurd situation, an arbitrary international dateline was established. By international consensus, it has become accepted that if a person crosses a certain longitude (~180 degrees east and west of Greenwich) from west to east he sets his calendar back one day. If he crosses it from east to west, he sets his calendar ahead one day. Since it is impossible to circumnavigate the earth without passing this dateline, such an adjustment will offset the effects of the "artificial day." The calendar day and day of the week for our globe-trotter and his neighbors will once again be synchronized.

Is there a similar dateline that resolves the double-date quandary in Jewish law? Will our world traveler observe Shabbat a day earlier than the rest of his countrymen because he has experienced an additional sunset? Or is he to set back his calendar at some point during his journey? It certainly seems logical to assume that in order to avoid the absurd situation described above there must be a Jewish dateline. Those living west of the line would be considered to be ending their Shabbat at the same moment that those living east of the line would be ending their Friday and just beginning their Shabbat. Where should this halachic dateline be drawn?

Interestingly enough, this question is discussed in numerous early Rabbinic sources. The Ba'al HaMe'or (Rav Zerachyah HaLevi, 13th cent. Provence) establishes a dateline based on a Gemara in Rosh Hashanah. We will present here a simplified version of his argument in order to try to understand his reasoning.

First, we must determine the first moment that the new moon will be visible to the naked eye, presuming that it were dark and the skies were clear. (When the moon passes between the earth and the sun it cannot be seen, because the side that reflects the sun's light is away from us. The moon rises and sets together with the sun and is not visible to us, because it is only lit on the side that is away from the earth. Only 24 hours after the point that the moon passes the sun, does the moon set enough time after sunset to visible as a thin sliver. At that moment, if the atmospheric condition are correct, the new moon can be sighted. This, says the Ba'al HaMe'or, is the first calculation which must be made.

Next, we must make the following calculation: If the moon can first be seen *before* midday on Tuesday, then Monday will be Rosh Chodesh [=the new month]. But if the moon can first be seen *after* midday on Tuesday, then Tuesday will be Rosh Chodesh.

The Ba'al HaMe'or explains: As one travels to the west the hour becomes earlier. If one travels three quarters of the way around the globe to the west, then it will be eighteen hours earlier than it is in Israel. If it is midday on Tuesday in Israel, then it would be sunset of Monday going into Tuesday eighteen hours to the west. That spot, eighteen hours to the west, is the Jewish dateline. If one were to travel just a bit more than eighteen hours to the west, one would leap forward by a day. Thus, if the moon appears just before midday on Tuesday in Israel, there will still be a place somewhere in the world, just short of the dateline, where it will be just before sunset on Monday. Since the moon can be seen somewhere in the world on Monday, Monday will be Rosh Chodesh.

But if the moon will not be visible in Israel until just after noon on Tuesday, then in that western most point, just short of the eighteen hour dateline, the moon will appear just after sunset, when it will already be Tuesday. If one travels just a bit farther, crossing the dateline, the moon will indeed appear before sunset, but having crossed the dateline, it will no longer be just before sunset of Monday going into Tuesday, but just before sunset of Tuesday going into Wednesday! Since there is no place on earth where the moon will be visible on Monday, Tuesday will be Rosh Chodesh.

The Ba'al HaMe'or clearly delineates the dateline: It is 270 degrees (or 18 hours) to the west and 90 degrees (or 6 hours) to the east of Jerusalem. One who travels 90 degrees to the east of Israel must turn his calendar back one day. This opinion is mentioned by Rav Yehudah HaLevi (12th cent. Spain) in his Sefer HaKuzari (2:20) as well.

The Ba'al HaMe'or explains why the Gemara chose the point six hours to the east of Jerusalem to be the point that marks the break between the earliest and the latest moment on earth. This point, he explains, marks the easternmost edge of the civilized landmass (= the Asian continent), where it meets the Great Ocean (= the Pacific coast). This is the first point of the mainland that the sun encounters in its east to west circuit. It therefore stands to reason that when the sun rises over this point, it should be considered the very first moment of "Monday" on the globe. East of that point, Sunday is just beginning and Monday will not start for yet another 24 hours. (It is interesting to note that traveling ninety degrees to the east of Jerusalem indeed brings one to a point just off the coast of China, not far from Shanghai.)

We may conclude, based on the words of the Ba'al HaMe'or, that a person who lives just to the east of the point ninety degrees east of Jerusalem would celebrate Shabbat a day later than a person living just to the west of that point.

Following the opinion of the Ba'al HaMe'or, we would be led to conclude that all of the regions east of the 90-degree line ought to keep Shabbat a day later than those to the west of that line. This presents the Jewish communities of the Far East with somewhat of a religious paradox. The secular dateline runs approximately 145 degrees to the east of Israel. Therefore, everyone who lives between 90 degrees east of Israel and 145 degrees east of Israel will be keeping Shabbat on the day which is popularly referred to as Sunday!

Throughout most of history this point was merely a theoretical one, as there was little contact between Jews of the West and the Far East. However, during the 1940's many European Jews, including a large group of yeshiva students from the famous Mir Yeshiva and other yeshivas, fled across Siberia and eventually to Japan in order to escape from the Nazi oppressors. Suddenly, the issue of when to observe Shabbat and Yom Kippur in the Far East became very pertinent. The yeshivas sent letters to all of the Torah authorities of the day, asking them for a clear halachic ruling on this issue.

Numerous authorities responded, in accordance with the apparent meaning of the Ba'al HaMe'or, that as soon as they found themselves beyond the 90-degree line, they must keep Shabbat on Sunday. (This opinion was upheld by Rav Yosef Dinkeles of Jerusalem in his book "Sod Nekudah Deletata," Rav Chaim Zimmerman in his book "Agan HaSahar," and many others.)

A second opinion is presented by the Chazon Ish (HaRav Avraham Yeshayah Karelitz, who resided at that point in Bnai Brak, Israel) in his pamphlet "Yud-Chet Sha'ot." The Chazon Ish insisted that it was illogical to divide a landmass into two different date-zones. Basing his position on the words of Rav Yitzchak ben Rav Yosef HaYisraeli (12th cent.) in "Yesod Olam," he decided that when the dateline passes through a landmass, that entire landmass should observe Shabbat at the same time as those who live to the west (or the Israel-side) of the dateline. Thus, even though the eastern most tip of Siberia is some 60 degrees to the east of the 90-degree line, Jews living there should observe Shabbat on the same day as their neighbors to the west. (i.e. on the day generally recognized as Saturday and not on Sunday.) Similarly, all of Australia should observe Saturday as their Shabbat and not Sunday.

*Islands* to the east of the 90-degree dateline, however, remain a halachic curiosity. They must observe Shabbat a day later, even though they are on the Israel side of the secular dateline. This means that Jews in Japan, the Philippines, New Zealand, etc., should keep Shabbat on the day commonly referred to as Sunday. Even though Japan is some 45 degrees west of the Bering Strait (the eastern tip of the Asian continent), since it is not part of the mainland, it will observe Shabbat a day later.

The Chazon Ish held to his position very firmly and insisted that the students and faculty of the Mir Yeshiva should feel no qualms whatsoever about observing Yom Kippur a day later (Thursday instead of Wednesday) during their sojourn in Japan. Likewise, they were to consider themselves beyond the dateline in regards to Shabbat and all of the festivals. (I have heard that because of the Chazon Ish's ruling, some people in eastern Australia do not go swimming on Sunday. By leaving the shores of their continent they would be crossing a dateline and would find themselves swimming into Shabbat!)

1. That it is to be drawn exactly ninety degrees to the east of Jerusalem.

2. The Chazon Ish's opinion that any landmass which stretches eastward past the 90-degree dateline extends the dateline to its eastern shore.

3. Perhaps we may suggest a third interpretation of the Ba'al HaMe'or's opinion, which would, incidentally, conform much more nicely with the secular international dateline. Perhaps the Ba'al HaMe'or did not intend for the line to be drawn just off the coast of China, but rather at the end of the Asian continental shelf. Although the dateline will still remain 90 degrees east of Israel at some latitudes, nevertheless, it will extend to eastwards in other latitudes to include not only Siberia, but the Japanese Islands as well. Similarly, the Philippine and Indonesian Islands will be included on our side of the dateline. This would put the halachic dateline much closer to the internationally recognized one.

   Support for this position can be drawn from the words of Radbaz (quoted above, section II), who asserts that as the sun crosses the Pacific the entire world is observing the Shabbat together. According to the two positions discussed earlier, the islands immediately off the Asian coast would only begin to observe Shabbat *after* the sun had crossed the Pacific. One might suppose that the Radbaz argues with the Ba'al HaMe'or and the Kuzari. However, in that very responsum, Radbaz himself cites the Kuzari as a consenting opinion. According to our suggestion, however, those islands would indeed start their Shabbat *before* the sun began to cross the Pacific.

(A) Rav David Shapiro (Jerusalem, early 20th century), in "Binyan Tzion" (1:14:8), puts the Jewish dateline 135 degrees east of Israel, or ~170 degrees *east* of Greenwich (ten degrees west of the international line).

(B) Rav Binyamin Rabinowitz Teumim, in "Gevul Yom," drew the dateline along the longitudinal line which passes along the easternmost point of Asia, or the Bering Strait. This line is ~170 degrees *west* of Greenwich (or ten degrees east of the international dateline.

(C) Rav Menachem Kasher, in "Kav Hata'arich Hayisraeli," insisted that one should keep Shabbat in accordance with to the internationally recognized dateline. In his opinion, in each community Shabbat depends upon the local custom.

(D) Rav Yonah Mertzbach, in "Alah Yonah," suggests that the line should be drawn at the midpoint between Asia and America, zigzagging in accordance with the contours of the two coasts, so that it will remain exactly at the mid-point for every latitude.

As a final note, it should be borne in mind that according to these latter four opinions, when the dateline is crossed by air of by sea another halachic disagreement has evolved. Some authorities claim that a person should adjust his calendar at the moment he crosses the imaginary line, while others claim that the date is not to be changed until one sets foot upon a landmass on the other side of the dateline.

And finally, I would like to remind the reader that this article does not represent an halachic position by any means. Should the question of the halachic dateline arise, be sure to consult your Local Orthodox Rabbi!