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© Copyright 1999, Jim Loy
To the left, we see a view of the earth
from above the North Pole. The top part is experiencing noon on Sunday. To the
right, it is morning, on Sunday, perhaps. Farther to the right, they have not
experienced the rising sun, yet. Is that Sunday, too? Perhaps. There is an
arrow pointing at 1 AM. Maybe that is on Sunday.
If we go the other way, we see that other portions of the earth are experiencing afternoon and evening. Perhaps these are also on Sunday. We have an arrow pointing at 11 PM.
If the two arrows, 11 PM and 1 AM, are both on Sunday, then they are 22 hours apart. And yet they are only 2 time zones apart. It turns out that, no matter how you do it (unless you have the whole earth have the same time of day), two adjacent time zones (somewhere) must be 23 hours different.
So, why not have these two adjacent time zones (that are 23 hours different) be in the middle of the Pacific Ocean, where there are relatively few people. That is what was done. And the dividing line (between days) is called the International Date Line. It was made to zig-zag, so adjacent islands would be in the same time zone.
See Time Zones and Daylight Savings Time. I hope to have a map on this page, eventually.