Can someone please explain the International Date Line to me? Obviously I understand time zones but how can there be a place where you always switch days?
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Replying to @BootlegGirl
It's not, it's called that because it's the place on the map where a new day officially starts first (tomorrow is Jan 13 and the first place it will be Jan 13 is on the western edge of the IDL, after which it will slowly sweep westward across the globe)
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Replying to @arthur_affect @BootlegGirl
This GIF explains it There can only be two different calendar days at once on Earth - as midnight moves across the globe, today slowly replaces yesterday, and tomorrow officially only comes into existence when midnight hits the IDL againpic.twitter.com/BNbMi9qsKZ
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Replying to @arthur_affect @BootlegGirl
So because this is how it works, there are always two places on Earth where you can go to "switch days" - one of them is crossing the line where it's currently midnight, which is constantly moving (which happens automatically if you sit still)
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Replying to @arthur_affect @BootlegGirl
The other is to go across the IDL and go "back" into yesterday At the exact instant that it's midnight on the IDL, yesterday is over everywhere and the whole Earth is briefly in the same day Then at 12:00:01 tomorrow starts and begins slowly moving across the world
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Replying to @arthur_affect @BootlegGirl
I dunno if I'm explaining this very well Obviously in reality the Earth is a continuous range of solar time from midnight to noon to midnight as the Earth turns But in order to divide time into calendar days we need to have a starting point where we can say the day starts
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Replying to @arthur_affect @BootlegGirl
So if it's 3 pm Monday on the west side of the IDL it's always 4 pm *Sunday* on the east side, because Monday started at midnight and moved west
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Replying to @arthur_affect @BootlegGirl
(Actually I looked this up and this is inaccurate - if we were logical we'd only have time zones ranging from UTC -12 to UTC +12 but instead some countries lobbied to get special UTC +13 and +14 time zones, which fucks it all up, but that's human society for you)
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Replying to @arthur_affect @BootlegGirl
I would suspect that those places were the time zone takes an unusual jag would also give you that situation.
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Technically the zigzag here represents the IDL *not* matching the time zones - the country of Kiribati still does time zones normally, it just flips what day it is
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The creation of the UTC +13 and +14 time zones is represented by the IDL swerving east to keep Kiribati in the "today" portion of the Earth rather than the "yesterday" as the new day starts
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