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Tomorrow-Today: The International Date Line

Posted by Keith on May 10, 2007 at 10:05 pm  

It’s all sort of confusing. Catch a morning flight from Majuro, The Marshall Islands, to Honolulu on, say, May 18, and you’ll arrive a few hours later in Honolulu on May 17. If you are then connecting to the mainland that same day, your connecting flight leaves the day before you left Majuro!

It’s all about the International Date Line, its exact opposite, the Prime Meridian, and “Zone Time.”


We have divided our planet into 25 rigidly divided time zones. The zones appeal to our human sense of orderliness I suppose; and they accommodate the Earth’s daily rotation around the Sun. They make the light at, say, 3 PM on a spring afternoon look pretty much the same anywhere on earth.

Zone Time is also known as both Greenwich Mean Time (the English town through which runs the Prime Meridian, or Longitude Zero), or Universal Coordinated Time (UTC). But ultimately they are just lines on a map, for our convenience, or confusion, as the case may be.

Out here where we’ve not seen another soul for more than five days, the ocean is certainly oblivious to whatever time we say it is. It has its own clock and does not need ours, thank you very much.

With 25 time zones, it figures that at the exact opposite side of the earth as the Prime Meridian, something funky would happen. And it does. If you are heading west and cross 180 degrees longitude, today becomes tomorrow, regardless what time of day you cross the line. If you are heading east and cross 180, today becomes yesterday, regardless of the time of day.

That is, unless you cross at a point where the Russians or the Americans bend the line at the Aluetian Islands for their mutual convenience, or where a number of Pacific Island nations do the same for theirs. Or maybe they do it just to confuse us.

In fact, nations and states bend time zones all the time, or they just flat out change them during the year. Spring forward. Fall back. Except in Arizona where we don’t use Daylight Savings Time. We already have more daylight than we know what to do with.

At this very moment it is 17:35 (5:35 PM) here in this time zone, just east of longitude 180. But there is nothing here except the ocean. And except for us, there are no people out here who really care that it is an hour earlier here than in the zone to our east, and an hour (and a day) later than in the zone to our west. And, frankly, after a week at sea, we don’t care all that much either.

What I do know is this: At our present course and speed, we should cross the International Dateline into tomorrow at, coincidentally, almost exactly midnight.

Oh my gosh! If we cross the line at exactly midnight will we leap into the day after tomorrow? Will we explode?

Where’s Rod Serling when you need him?

I’ll write again tomorrow, or the day after tomorrow, or whatever its going to be on the other side!

–Keith


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