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 Losing or gaining a day in your life!


February 2018

International Date Line

It is a funny story...the couple who booked a cruise to celebrate their 25th wedding anniversary travelling from America to Japan but found their anniversary did not exist because they crossed the International Date Line and went from Tuesday to Thursday missing out the special date entirely!

As more and more of us travel longer distances, the International Date Line can cause lots of confusion. It is not as if it is even a straight line, or clear cut as the line zigzags around various political borders to keep one country in the same time zone.

The basis of time zones of course is so that everyone has daylight hours at roughly the same time, with the sun rising in the morning and setting in the evening wherever you live.

While early sailors were aware of changes in daylight hours, the first real date-line problem occurred in association with the circumnavigation of the globe by Magellan in 1519 through 1522 when some of the sailors worked out they were on different days. This phenomenon caused such great excitement at the time that a special delegation was sent to the pope to explain this temporal oddity to him.

But it wasn’t until 1884 that representatives from 26 countries attended an International Meridian Conference in Washington DC, America, and decided on the details to establish the International Date Line. It was agreed that the day should change down a line from the north to South Pole on the 180 degree meridian, exactly opposite the 0 degrees of Greenwich.

This it was agreed sorted things out so that as you travelled around the world, you either gained or lost increasing number of hours until you did a 24 hour jump to get back to the right time.

But of course no country wanted to be divided by a day, so the International Date Line zigzags a little to ensure every nation or island group is within the same time zone.

There have also been instances where alterations have been necessary. In 2011 Samoa decided to miss out on December 30th totally. Its problem was that on its original time zone near to the International Date Line, when it was Friday there it was Saturday in New Zealand, and then it was Sunday in Samoa it was already Monday in Australia. The Samoan authorities worked out they were losing two working days a week for their international trade, so they swapped sides to go west of the date line and now are far more in line with their main trading partners.

One of the biggest zigzags occurs around Kiribati, an island nation of 32 atolls that straddles the equator. In 1995, Kiribati moved a chunk of the line to the east so that the entire country was on the same side, and they now capitalize on their position by celebrating New Year ahead of most others.

An interesting little snippet is that for two hours each day, between 10 am and 11.59am universal standard time, three different calendar dates exist at the same time in different places in the world. For instance, at 10.15 UTC time on Thursday, it is 23.15 on Wednesday in American Samoa, Thursday across most of the world, but already 00.15 on Friday morning in Kiritimati.

The main thing is to factor in the change of date if you ever plan to fly across the Pacific. The easiest thing to remember is “west is best”…when you travel west to add a day. Travelling from west to east, and as you cross the International Date Line you will go back to where you were 24 hours before.

For a full albeit technical explanation, a good site to visit is international-date-line-explained

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