Five Minute Trivia
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Five Minute Trivia
Earth's Time Machine: The International Date Line
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If you want to turn today into tomorrow, you don't need to wait for science to invent something. You can just go west until you cross 180 degrees longitude. That's where the International Date Line is located. On today's show, we talk about what it is and why it's needed. Special appearances by Gary Cooper and The Ghostbusters.
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I'm so glad we're finally here. Nine hours of flying is too long.
SPEAKER_00Actually, it was more than a day.
SPEAKER_01What are you talking about? I watched two movies, took a nap, and crawled around the floor looking for one of your earbuds. That's nine hours.
SPEAKER_00We left on Monday and now it's Tuesday.
SPEAKER_01No. We left Monday morning in Honolulu, and now it's Monday evening in Tokyo. Which means that we should get dinner and go find a karaoke place.
SPEAKER_00No one wants to hear what you're saying. And it's Tuesday because we crossed the international dateline.
SPEAKER_01The what now?
SPEAKER_00It's like a time machine in the middle of the Pacific Ocean. If you cross it going west, you add a day. If you cross it going east, you go back to the day before.
SPEAKER_01Wait, so because of this international dateline thing, you mean people could be listening to this the day before we even recorded it?
SPEAKER_00Possibly.
SPEAKER_01That sounds crazy. What's the point of that?
SPEAKER_00If only there was a podcast out there that could explain what it is and why it's needed.
SPEAKER_01Yeah. If only.
SPEAKER_02We choose to go to the moon! The Rum Tum Thugger is a curious cat. Hundred billion other galaxies.
SPEAKER_01Welcome to Five Minute Trivia, where we're making the world smarter five minutes at a time. I'm your host, R. M. Zuberi. In 1872, Jules Verne wrote a novel called Around the World in Eighty Days. It's about a man named Phileas Fogg who makes a wager that he can circle the whole planet in well eighty days. It's a great adventure story. Fogg takes boats and trains and a wind-powered sled while he's being pursued by a detective who thinks he's a bank robber. Fogg eventually makes it back to London, but he's late. Or at least he thinks he is, because he has already observed eighty sunsets. But he's informed that London has only observed seventy-nine. He's actually a day early. Phileas Fogg clearly didn't read a history book, but fortunately his creator did. Four hundred years before Fogg left London, an Arab geographer predicted that anyone who circumnavigated the globe would accumulate a one day offset to the local date. This was confirmed by the voyage of Francis Magellan, whose expedition was the first to do that. Not Magellan himself, he died along the way, but when his crew landed in Cape Verde a year later, the local date was a day ahead of the ship's logs. Wait, so Fog was a day early, and Magellan's guys were a day late. What madness is this? Well, Fog sailed east and Magellan sailed west, that seemed to make a difference. But again we ask, what is this madness? So there's a good explanation for this.
SPEAKER_02Fire and brimstone coming down from the skies, rivers and seas boiling. Forty years of darkness, earthquakes, volcanoes, the dead rising from the grave, human sacrifice, dogs and cats living together, mass terrium.
SPEAKER_01Uh okay, so there's a there's a better explanation, actually. A day on Earth means that the planet completes one full rotation in 24 hours. That's a 360 degree revolution. Matmakers divided that 360 degrees into 24 north-south lines of longitude that are 15 degrees apart. Each line corresponds to an hour of the Earth's rotation. So with every move across a line of longitude, the sunrise occurs either an hour earlier or later. If you move east, you're moving toward the sunrise, and it will occur an hour earlier every time you cross a longitude line. The opposite happens when you move west. Move across enough lines and you'll either gain or lose a full day. Throughout history, people have thought of noon as the time when the sun is at its highest point in the sky, hence the name High Noon, which is also a western starring Gary Cooper.
SPEAKER_02A terror-stricken town left him to face four killers single-handed. At high noon.
SPEAKER_01So if you want everyone to have noon occur when the sun is highest in the sky, you need some system to adjust local time according to a standard. In other words, you need time zones. You typically add or subtract an hour as you cross time zones. Let's say you're moving east. Every time you cross a line of longitude, you move your watch forward by an hour. These days, our phones do that automatically. The problem is that if you went all the way around the planet, you would end up a day ahead when you got back home. The reverse would happen if you traveled west. That is why the international dateline was created. That is where the day officially starts and ends. If you cross it moving east, you go back to the previous day. If you cross it moving west, you jump ahead to the next day. This ensures that your day and the day of the place you're traveling to match up. The international dateline is located at 180 degrees longitude. Why there? Well, if you look at a map, you'll see that there's a lot of ocean out there and not much else. If you're gonna pick a place where days turn over, you don't want that to run through any heavily populated areas. Like, just imagine what Monday mornings would be like if the date line ran through your house. Instead of throwing your alarm clock out the window when you want to sleep in, you could just move to the part of the house where it's still Sunday. So 180 degrees longitude runs through the part of the Pacific Ocean that's mainly empty, but not entirely. There are some islands that the date line would run right through, so governments just move the line around as they see fit. The US and Russia have adjusted the line to ensure that all of their Pacific holdings observe the same day as the rest of their respective countries. In some cases, the line zigs and zags as much as 30 degrees. Still, some amount of inconvenience is inevitable. Samoa and American Samoa are just miles apart, but on opposite sides of the line, so a flight between them technically takes just minutes, but according to the clock, it's more than a day's travel. Just a couple of notes for Trivia Knight. The first place on Earth to experience a new day and a new year is the Republic of Kiribati, specifically Caroline Island. It was the first to welcome the year 2000, so Kiribati renamed it Millennium Island. Jules Verne was not the only writer to take advantage of real world time travel. Edgar Allan Poe also wrote a short story called Three Sundays in a Week, in which two ship captains circumnavigate the Earth in opposite directions and can't decide what day it is when they meet. That's all for this week. Join us next Monday, uh or maybe Sunday, or I don't know, Tuesday. Anyway, we'll see you next time on Five Minute Trivia. Thanks for listening.
