THE INTERNATIONAL DATE LINE

 

 Jeanie October 2022


Long, long before the introduction of the international date line, the Arab geographer Abulfeda (1273-1331) predicted that circumnavigators would gain one day.  He was proved right in 1522 at the end of the Magellan-Elcano circumnavigation – the first successful navigation around the world.   After sailing westward from Spain, the expedition called at Cape Verde in the Atlantic Ocean for provisions on Wednesday 9 July 1522 (ship’s time) - however locals told them that it was actually Thursday 10 July.  The crew was very confused as they had meticulously recorded every day of their 3 year journey, without fail.

The international date line (IDL) was not drawn up until 1884.  It is an imaginary line of demarcation that passes through the mid-Pacific at roughly 180 degrees longitude.  It is halfway around the world from the prime meridian (0 degrees longitude) which is in Greenwich London.  The IDL runs from the North Pole to the South Pole and marks the western and eastern hemisphere divide.   It’s not straight but curves round landmasses and national borders.  For example it leans east at the Bering Straight between Asia and North America, making Russia a day ahead of Alaska, even though they are only about 50 miles apart.


The British colony Kiribati (Christmas Island) was just west of the IDL.  It became independent in 1979 and gained the Phoenix and Line Islands, situated just east of the IDL, meaning the country now straddled the IDL.  Business could only be conducted by radio or telephone on the 4 days which were weekdays on both sides.  To fix this, Kiribati simply removed Saturday 31 December for its eastern half:  Friday 30 December 1994 was followed by Sunday 1 January 1995.  By adding 24 hours to the clocks in the Phoenix and Line Islands, Kiribati put a dent in the IDL, moving it all the way to 150 degrees longitude.  As a result of this dent, for the 2 hours between 1000 and 1159 GMT each physical day, three different calendar dates are happening, at the same time, in different parts of the world.  When it is 2315 Wednesday in neighbouring American Samoa, and Thursday in the UK (GMT), it is 0015 Friday in Kiribati.  Kiribati also celebrates the new year before anyone else which is a great draw for tourism!


Some Christian churches solemnly observe a Sabbath day on a particular day of the week.  This gets very confusing when their churches are near the IDL.  The days are legally different but physically the same, so the question is, which Saturday on either side of the IDL is the “real” Saturday?   A really big problem for Seventh Day Adventists, Seventh day Baptists etc.  Bless.

Even though the IDL did not yet exist, the concept appears in Jules Verne’s book, Around the World in Eighty Days (1873).   The protagonist, Phileas Fogg, travels eastward around the world.   He had a bet with friends that he could do it in 80 days.  To win the bet Fogg had to return by 8.45pm on Saturday 21 December 1872.  However, after lots of adventures and mishaps along the way, Fogg reached London at 8.50pm on 20 December, although he believed it to be Saturday 21 December and that he had lost the wager by a margin of only 5 minutes.  The next day it was revealed that is it Saturday, not Sunday, and Fogg arrives at his club just in time to win the bet.  Verne explained that 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.

 


 

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