Dear Rabbi, On December 29, 2011, the Pacific island of Samoa has changed from the east side of the International Date Line to the west, to be in sync with Australia and New Zealand, its main sources of tourism and business. I’ve been wondering if there are any implications in Jewish law. When will Samoan Jews and Jewish tourists observe the Sabbath? Answer: You ask a good question. Jews worldwide celebrate the Sabbath, or Shabbat, on the seventh day of the week. But what happens when a country skips a day and changes their Friday to Saturday? The concept of a date line, and the fact that a traveler would either gain or lose a day after circumnavigating the globe, had been discussed in Jewish works hundreds of years before the establishment of the International Date Line. In fact, the first to articulate the need for a date line was the Jewish philosopher Rabbi Yehudah Halevi (1075–1141), in his classic work, the Kuzari.

History of the International Date Line In 1884 Greenwich, England, was chosen as the central point for time and date calculations (the prime meridian), and the International Date Line sits at exactly 180° longitude from there. By using Greenwich as the prime meridian, the International Date Line falls conveniently in the Pacific Ocean. In those few areas where it should traverse a landmass, the line was slightly bent to avoid dividing countries. The date line is not governed by international law, and it is up to the individual countries to choose which side of the line they wish to be on. Occasionally a country decides to switch sides, as the islands of Samoa and Tokelau did last week. To determine the Jewish view on the date line and Sabbath observance, we must examine four major opinions in halachah, Jewish law.

1. 90° East of Jerusalem Rabbi Zerachiah ben Isaac Halevi Gerondi (12th century) and Rabbi Yehudah Halevi opined that the date line runs 90° east of Jerusalem. The reasoning behind their opinion is that we consider Israel, and more specifically Jerusalem, to be the center of the “inhabited” world (at that time). In other words, six hours, or 90°, to the east and west of Jerusalem at one time encompassed the entire known world. The other side of the world (i.e. the western hemisphere) was considered the “lands of the sea.” Since the day begins to the east of Jerusalem, the quarter of the world to the west of Jerusalem, together with the entire western hemisphere, completes the day. Thus, the date line is 90°, a quarter of the globe, east of Jerusalem, or about 125° east of Greenwich. The problem with this is that the date line would cut right through two huge landmasses—Asia (Russia, China, Korea) and Australia—and several Southeast Asian islands. You could end up with two people standing right next to each other, where for one the Sabbath is starting and for the other it is ending! As such, Rabbi Avraham Yeshayah Karelitz, known as the Chazon Ish, bases the 90° on the knowledge that the major landmass to the east of Jerusalem ends at that point. Since the entire landmass is on one side of the date line, the line actually zigzags, and so Siberia, Korea, eastern China, and Australia are considered to be on the west of the date line, while Japan and New Zealand are on the east side. According to the Chazon Ish’s date line, Sabbath in Japan and New Zealand is actually on Sunday.

2. 180° East of Jerusalem Rabbi Yechiel Michel Tucazinsky says that the date line runs 180° east of Jerusalem. He explains that because Jerusalem is considered the center of the land given to the Jewish people, it is also considered the center of the world according to Jewish law. Therefore, the date line would be located exactly 180° opposite Jerusalem, which would also enable every Jew in the world to observe at least 12 hours of the Sabbath together with those who live in Jerusalem. Since Jerusalem is 35° east of Greenwich, the date line would be 35° east of the current International Date Line, or 145° west of Greenwich. Accordingly, Hawaii and parts of Alaska would be on the western side of the date line, and the Sabbath in Hawaii would be on Friday. However, it is possible that according to this opinion the line would zigzag around Alaska, in order that it follow the majority of the landmass.

3. Mid-Pacific: Closely Resembling the International Date Line Rabbi David Shapira opined that the date line is approximately 135°, or 9 hours, east of Jerusalem. This would make the date line approximately 170° east of Greenwich, which is only 10° off the International Date Line. According to R. Shapira, however, the line zigzags, slanting toward the Siberian coast as it goes through the Bering Straits, and then through the Pacific at 177°. Then it turns east of New Zealand. His rationale for this placement is based on the statement of our sages that G‑d positioned the sun in the heavens at the end of the third hour of the fourth day of creation. Now, if it is the third hour of the day in Jerusalem, then three hours (45°) to the east of Jerusalem it would be noon, and nine hours (135°) east of Jerusalem the sun would be setting. To say that the sun was placed in the heavens on the fourth day, it must have been the fourth day on the entire planet. Therefore, we have to say that east of where the sun was setting, the fourth day was just beginning. Accordingly, Hawaii and Japan would observe the Sabbath on Saturday.

4. There is No Specific Date Line According to Rabbi Menachem Kasher, since there is no clear tradition or Talmudic source, one should observe the Sabbath when the locals do. Since we, as individuals, are commanded to count six days and rest on the seventh , when the first Jews settled in remote areas (over a long period of time), they simply continued counting six days and resting on the seventh. It was only later, when travel became more frequent, that the question of changing the dates arose. As such, there is no need for any community to change dates from their established custom (which is basically the same as following the International Date Line). However, travelers continue counting six days from the last Sabbath they observed, and the seventh day is the Sabbath. Only once the travelers arrive at their destination would they follow the local Jewish community’s Sabbath.

The Samoa Issue The Jewish Telegraphic Agency tracked down one Jew living in Samoa, and there may be many more. When would this person mark future Sabbaths? It would depend on which of the above opinions he follows. According to the first opinion—that the date line is 90° east of Jerusalem—then it runs west of Samoa, so until now the Sabbath was on Saturday. But now that Samoa has switched to the western side of the International Date Line, Sabbath would actually be on Sunday. According to the second opinion—that the date line runs 180° east of Jerusalem—these islands, as well as Hawaii, were always west of the line. So until now the Sabbath in Samoa was actually on Friday, but now it will be on Saturday. If, according to the third opinion, we say that the date line is 135° east of Jerusalem, then it runs to the west of Fiji. This means that until now the Sabbath in Samoa was on Saturday, but from now on it will be on Sunday. According to the last opinion, Sabbath observance is based on an existing Jewish community. If a traveler or tourist were to arrive on an island with no Jewish community, the traveler would continue to keep the Sabbath according to his or her individual count, as if still on a boat.