Around the World in Eighty Days ...
Most of us would have heard of or read an abridged version of Jules Verne's Around the world in 80 days in our childhood. (written in 1873)
In the story, the main protagonist, Phileas Fogg, travels eastward around the world as a challenge with his friends, that he can traverse the world in 80days and come back to his starting point. Fogg is supposed to come back to London, latest by 8:45 pm on Saturday, 21 December 1872. And meet his friends the next day.
However, the journey suffers a series of delays and when Fogg reaches London, it is 8:50 pm on Saturday, 21 December, according to him and he believes that he has lost the wager by a margin of only five minutes. The next day, however, it is revealed that the day is Saturday, not Sunday, and Fogg arrives at his club just in time to win the bet.
Verne explains it thus:
In journeying eastward Fogg had gone towards the sun, and the days therefore diminished for him as many times four minutes as he crossed degrees in this direction. There are three hundred and sixty degrees on the circumference of the earth; and these three hundred and sixty degrees, multiplied by four minutes, gives precisely twenty-four hours - that is, the day unconsciously gained. In other words, while Phileas Fogg, going eastward, saw the sun pass the meridian eighty times, his friends in London only saw it pass the meridian seventy-nine times.
Fogg had thought it was one day later than it actually was, because he had not accounted for this fact. During his journey, he had added a full day to his clock, at the rhythm of an hour per fifteen degrees, or four minutes per degree, as Verne writes.
It is nothing short of brilliant that Jules Verne thought about this concept and kept it as a plot point in a seemingly non Sci Fi novel.
As a child, I was really intrigued and often wondered, if all these jet setting, Globetrotting people kept adding days to their lives!
Subsequently I heard about the International Dateline - invented just to solve the above issue, but did not delve deep into the hows, whys and wheres of it.
Till recently, I read another book
The Island of the Day Before ...
This finally led me to read up on the International Dateline, and learn about it in detail.
What is International Dateline?
Open Dictionary defines it as
An imaginary line on the Earth's surface that is internationally agreed upon as the place where each new calendar day begins. (which is rather obscure to say the least)
To elaborate -
The International Dateline is an internationally accepted demarcation on the surface of the Earth, running between the South and North Poles and serving as the boundary between one calendar day and the next. Areas to the west of the date line are one calendar day ahead of areas to the east. In other words, Crossing the date line eastbound decreases the date by one day, while crossing the date line westbound increases the date.
It is not a straight line, however. It passes through the Pacific Ocean, roughly following the 180.0° line of longitude and deviating to pass around some territories and island groups. These deviations generally accommodate the political and/or economic affiliations of the affected areas.
Why do we need it?
The 14th century Arab Geographer Abulfeda predicted that circumnavigators would accumulate a one-day offset (plus or minus) to the local date, based on his calculations and research.
This phenomenon was confirmed in 1522 at the end of the Magellan–Elcano expedition, the first successful circumnavigation. After sailing westward around the world from Spain, the expedition called at Cape Verde for provisions on Wednesday, 9 July 1522 (ship's time). However, the locals told them that it was actually Thursday, 10 July 1522. The crew was surprised, as they had recorded each day of the three-year journey without omission.
Cardinal Gasparo Contarini, the Venetian ambassador to Spain, was the first European to give a correct explanation of the discrepancy.
When?
The International Meridian Conference (1884)...
In October 1884 astronomers and representatives from 25 countries convened in Washington at the International Meridian Conference to recommend a common prime meridian for geographical and nautical charts that would be acceptable to all parties concerned. Here it was decided that, the Greenwich Meridian should be adopted as the Prime Meridian for Time zones, rather than the 180° meridian, because this mostly passed over water, making it difficult to draw/mark or define. It was decided that the 180° meridian would be retained only as a Dateline. However, no attempts were made during this conference to specify the exact course of the date line when it happened to cross land or pass through island groups.
Infact, the Conference explicitly refused to propose or agree to any time zones, stating that they were outside its purview. The conference resolved that the Universal Day, midnight-to-midnight Greenwich Mean Time (now redefined and updated as Coordinated Universal Time, or UTC), which it did agree to, "shall not interfere with the use of local or standard time where desirable". From this comes the utility and importance of UTC or "Z" ("Zulu") time: it permits a single universal reference for time that is valid for all points on the globe at the same moment.
“There is no International Date Line. The theoretical line is 180° from Greenwich, but the line actually used is the result of agreement among the commercial steamships of the principal maritime countries.”
Based on the recommendations of the hydrographic departments of the British and the American Navy, the date line was marked & sanctified from 1899 and 1900.
Subsequently, the following adjustments of the dateline took place
In 1900 near the island chain of Hawaii and between Samoa and the Chatham Islands, a small westward extension of the date line had been deemed necessary so that the small islands of Patrocinio and Morrell Island featured on most 19th-century nautical charts would keep the same date as Hawaii. By 1910 the non-existence of these islands had become firmly established and the date line was straightened out at that point.
Next it passed to the east of Wrangel Island and the Chukchi Peninsula, the easternmost part of Russian Siberia. This is to ensure all of Russia is to the west of the IDL, and all of the United States is to the east except for a few insular areas.
The IDL circumscribes Kiribati by swinging far to the east, almost reaching the 150°W meridian. South of Kiribati, the IDL returns westwards but remains east of 180°, passing between Samoa and American Samoa. Thus all islands on the side of Samoa including New Zealand's Kermadec Islands fall to the west and have the same date, while American Samoa, Cook Islands and French Polynesia fall to the East and are one day behind.
The IDL then bends southwest to return to 180°. It follows that meridian until reaching Antarctica, which has multiple time zones. Conventionally, the IDL is not drawn into Antarctica on most maps.
Circumnavigating the globe -
People traveling westward around the world must set their clocks:
- Back by one hour for every 15° of longitude crossed, and
- Forward by 24 hours upon crossing the International Date Line.
People traveling eastward must set their clocks:
- Forward by one hour for every 15° of longitude crossed, and
- Back by 24 hours upon crossing the International Date Line.
De facto and de jure date lines...
There are two ways time zones and thereby the location of the International Date Line are determined, one on land and adjacent territorial waters, and the other on open seas.
All nations unilaterally determine their standard time zones, applicable only on land and adjacent territorial waters. This date line can be called de facto since it is not based on international law, but on national laws. These national zones do not extend into international waters.
The nautical date line, not the same as the IDL, is a de jure construction determined by international agreement. It is the result of the 1917 Anglo-French Conference on Time-keeping at Sea, which recommended that all ships, both military and civilian, adopt hourly standard time zones on the high seas. The United States adopted its recommendation for U.S. military and merchant marine ships in 1920. This date line is implied but not explicitly drawn on time zone maps. It follows the 180° meridian except where it is interrupted by territorial waters adjacent to land, forming gaps—it is a pole-to-pole dashed line. The 15° gore that is offset from UTC by 12 hours is bisected by the nautical date line into two 7.5° gores that differ from UTC by ±12 hours.
In theory, ships are supposed to adopt the standard time of a country if they are within its territorial waters within 12 nautical miles (14 mi; 22 km) of land, then revert to international time zones (15° wide pole-to-pole gores) as soon as they leave. In practice, ships use these time zones only for radio communication and similar purposes. For internal (within-ship) purposes, such as work and meal hours, ships use a time zone of their own choosing.
Cartographic practice...
The IDL on all maps is based on the de facto line and is an artificial construct of cartographers, as the precise course of the line in international waters is arbitrary. The IDL does not extend into Antarctica on the world time zone maps.
The IDL on modern CIA (United States Central Intelligence Agency) maps reflects the most recent shifts in the IDL.
On the other hand the HMNAO (United Kingdom's His Majesty's Nautical Almanac Office) maps do not draw the IDL in conformity with recent shifts in the IDL; they are drawn virtually identical to the line adopted by the UK's Hydrographic Office about 1900. However, HMNAO labels Island groups with their time zones, thus keeping them updated with National and Nautical Time Zones.
In fact, the islands of eastern Kiribati are actually "islands" of Asian date (west side of IDL) in a sea of American date (east side of IDL). Similarly, the western Aleutian Islands are islands of American date in a sea of Asian date.
No international organization, nor any treaty between nations, has fixed the IDL drawn by cartographers.
Issues with Religion...
Generally, the Christian calendar and Christian churches recognize the IDL. Christmas for example, is celebrated on 25 December as that date falls in countries located on either side of the IDL. Thus, Christians in Samoa, immediately west of the IDL, will celebrate the holiday a day before Christians in American Samoa, which is immediately east of the IDL.
However a problem arises when a day & not a date is observed. Like the Sabbath on Saturday. Because, notwithstanding the difference in dates, the same sunrise happens over American Samoa as happens over Samoa a few minutes later, and the same sunset happens over Samoa as happens over American Samoa a few minutes earlier. In other words, the secular days are legally different but they are physically the same; and that causes questions to arise under religious law. Because the IDL is an arbitrary imposition, the question can arise as to which Saturday on either side of the IDL (or, more fundamentally, on either side of 180 degrees longitude) is the "real" Saturday. This issue (which also arises in Judaism) is a particular problem for Seventh Day Adventists, Seventh Day Baptists, and similar churches located in countries near the IDL. Many countries observe Sabbath on part Fridays and part Sundays too, because of this.
The Islamic calendar and Muslim communities recognize the convention of the IDL. In particular, the day for holding the Jumu'ah prayer appears to be local Friday everywhere in the world. The IDL is not a factor in the start and end of Islamic lunar months. These depend solely on sighting the new crescent moon. The fasts of the month of Ramadan begin the morning after the crescent is sighted. That this day may vary in different parts of the world is well known in Islam.
The concept of an International Date Line in Jewish law is first mentioned by 12th-century decisors. But it was not until the introduction of improved transportation and communications systems in the 20th century that the question of an International Date Line truly became a question of practical Jewish law. However, now the IDL is taken as a de facto line by Jews, the world over, who observe Shabbath on local Saturday.
IDL Crossing Ceremonies...
Ceremonies aboard ships to mark a sailor's or passenger's first crossing of the Equator, as well as crossing the International Date Line, have been long-held traditions in navies and in other maritime services around the world.
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Line-crossing ceremony aboard Méduse on the first of July 1816. |
When Jules Verne wrote his book, the concept of a de jure International Date Line did not exist. Yet it was his sheer genius coming up with a story like that, that could stir the imagination of so many children and adults alike.
In today's world, if Phileas Fogg travelled across the globe, once he reached the IDL, he would have readjusted his clock/ calendar. Thus, the day he would add to his clock through his journey would get automatically removed upon crossing this imaginary line.
However, this pragmatic solution is rather anticlimactic for my imaginative premise of the Rich and the Famous adding endless days to their lives!
