International Date Line

It's a weird thing to think about, but often, when we travel across the International Date Line, we have no alibi for a certain day on the calendar. Other times we live a day that never seems to end! It's a weird thing.

It's especially fun to try to explain all that to children.

Imagine a conversation in the plane

across the Pacific Ocean.

"Daddy, what day is it?"

"Well, do you mean where we've come from or where we're going?"

"Daddy, just answer the question."

"Hmm, legally we start functioning on arrival time but biologically we are in limbo, and then if we were to have to return to our departure city then . . . ."

"Mum, what's today's date?" . . . .

Another funny thing is trying to navigate between dates

when communicating via the internet knowing that the date of your writing may be before or after the date of the one reading.

For example, in the US it is the birthday of my friends Cheryl & Cindy. Judith's birthday is the same day but because she lives in Zimbabwe, her birthday is nearly over.

Marcus & Jaime's birthdays are on the 4th which is today in New Zealand but tomorrow in USA.

Now another dilemma arises. Do we celebrate our birthday on the date & time of the city in which we were born or by the calendar and time zone in which we live?

I think I was born in the wee hours of the morning, so I rarely think of celebrating it at the time, but you get my drift.

Hope I won't need an alibi for any of those days spent enroute.

Wikipedia explains it thus:

The first date line problem occurred in association with the circumnavigation of the globe by Magellan's expedition (1519–1522). The surviving crew (a mere 18 men on 217 who departed) returned to a Spanish stopover sure of the day of the week, as attested by various carefully maintained sailing logs. Nevertheless, those on land insisted the day was different. This phenomenon, now readily understandable, caused great excitement at the time, to the extent that a special delegation was sent to the Pope to explain this temporal oddity to him.

The effect of ignoring the date line is also seen in Jules Verne's book Around the World in Eighty Days, in which the travelers, led by Phileas Fogg, return to London after a trip around the world, thinking that they have lost the bet that is the central premise of the story. Having traveled the direction opposite to the one taken by Magellan, they believe the date there to be one day later than it truly is. Lest anyone accuse Fogg of cheating by obtaining one extra day, this is not so. On average, each travel day was 18 minutes short of a full 24 hours, accumulating to one full day, which they failed to correct as we would by setting our calendar back a day in mid-Pacific.

The date line is also a central factor in Umberto Eco's book The Island of the Day Before, in which the protagonist finds himself on a becalmed ship, with an island close at hand on the other side of the International Date Line. Unable to swim, the protagonist's writings indulge in increasingly confused speculation of the physical, metaphysical and religious import of the date line.The International Date Line can cause confusion among airline travelers. The most troublesome situation usually occurs with short journeys from west to east. To travel from Tonga to Samoa by air, for example, takes approximately two hours but involves crossing the International Date Line, causing passengers to arrive the day before they left. This often causes confusion in travel schedules, like hotel bookings (unless those schedules quote times in UTC, but they typically do not since they must match domestic travel times, local transport, or meeting times).

FYI: The International Date Line (IDL) is an imaginary line on the surface of the Earth opposite the Prime Meridian where the date changes as one travels east or west across it. Roughly along 180° longitude, with diversions to pass around some territories and island groups, it mostly corresponds to the time zoneboundary separating −12 and +12 hours Coordinated Universal Time (UTC) (Greenwich Mean Time – GMT). Crossing the IDL travelling east results in a day or approximately 24 hours being subtracted, and crossing west results in a day being added.