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Imagine that you are travelling from the United States to Japan on Sunday morning. You are excited to see Mount Fuji in Japan and your mouth is already watering thinking of Japanese cuisine. But, as soon as you cross the Pacific Ocean and reach Japan you will find that it’s suddenly Monday. On the reverse trip when you fly from Japan to the United States on Friday you will find out that it is suddenly Thursday. This happens as you cross the International Date line.
What is the International Date Line?
The international date line (IDL) is an imaginary line that is running from the North Pole to the South Pole. It passes through the middle of the Pacific Ocean, roughly following the 180° line of longitude. The imaginary line is located halfway around the world from the prime meridian — the 0 degrees longitude line in Greenwich, England.
It is also commonly known as the ‘Line of Demarcation’. This is because IDL separates two calendar dates. If you are travelling to the west and cross the date line then you gain a day. Although if you are travelling to the east and cross the date line you will lose a day.
For example, if you are travelling eastward across the Pacific Ocean on 22nd February when you will reach your destination you will jump backwards to 21st February. Although if you are travelling in the opposite direction i.e westward you will jump forward to 23rd February.
Now, it does not necessarily mean that the difference will always be 24 hours. Depending upon the time zone the country follows and the rate of speed at which you are travelling the difference can be more than 24 hours or less.
The International Date Line carries no legal status which means that countries are free to choose the date and time zone that their country will follow.
Why is the International Date Line Important?
The international date line, which runs around the surface of the Earth at 180 degrees longitude, passes through the Bering Strait, Pacific Ocean, Arctic Oceans, Antarctica, Fiji, Tonga and other islands. The imaginary line is not straight. Instead, it has been drawn in a zig-zag pattern.
The time difference on either side of this imaginary line is 24 hours. If the line was present in the straight line then it would mean that both the places on either side of the line will have different dates on the same day. There would be so much confusion if one side of the line is observing one date of the week while the other side is following some different date.
How the International Date Line Was Determined?
The international date line was determined in 1884 during the International Meridian Conference. This conference took place in Washington D.C. During this conference representatives of 26 nations were present. President Chester A. Arthur told the committee the importance of implementing standards for an international agreement on time and longitude.
By the end of the 19th Century, the whole world witnessed an increase in commerce and the establishment of advanced communication technologies. A lot of nations were dependent on each other. To avoid any kind of confusion the decision to set clocks to a world standard was taken.
The conference considered the prime meridian in Greenwich as the world’s single ‘initial meridian’. This meridian was recognised because over two-thirds of ships were already utilising the zero longitudes.
The International Date Line was the result of the conference’s Third Resolution. According to this resolution, meridian longitude would be considered in two directions up to 180 degrees.
Although it was on the countries to enforce this rule of the imaginary line. Even today, IDL does not come under international law. It is used by all the countries even today because it ensures smooth communication between two nations and maintains consistent international databases.
Conclusion:
The international date line is extremely important as it helps to determine the time zones of different nations. Always remember that it is an imaginary line that is running from the North Pole to the South Pole. It is located halfway around the world from the prime meridian — the 0 degrees longitude line in Greenwich, England. The time difference on either side of this imaginary line is 24 hours. If you travel eastward then your day decreases by 24 hours. On the other hand, if you travel westward then your day increases by 24 hours.
