Textbook Topics: International time zones

Chapter 11 of the Standard textbook is World Locations and Times, with the exercises within that chapter specifically focusing on latitude and longitude, time, timetables, and international time zones.

I loved studying World Locations and Times when I was in high school (back then it was called Spherical Geometry), so much so that I was a little saddened by the fact that it’s one of the shortest chapters in the textbook.

Out of all of the World Locations and Times topics listed above, the one that most interested me was (and still does) international time zones. The fact that I can be lying in bed at midnight and people on the other side of the world are living their lives and going about their days has always fascinated me.

The textbook provided some interesting facts on international time zones, specifically on when they were established and reasons for their differences,

“Since 1884, the world has been divided into standard time zones, with roughly one hour difference for every 15 degrees of longitudes. Some countries make variations for geographical and/or administrative reasons. For example, Australian Central Standard Time (ACST) is 9.5 hours (not 9 hours) ahead of UTC (Coordinated Universal Time) and China has only one time zone (UTC+8) even though it stretches across four.”

The textbook also provided some interesting facts on the International Date Line, which included:

  • It runs on the opposite side of the world to the prime meridian.
  • It runs from the North Pole to the South Pole through the Pacific Ocean between Fiji and Hawaii.
  • It also runs between the Samoan Islands.
  • If you cross the International Date Line travelling east (e.g. going from Australia to the USA), today becomes yesterday and you ‘gain’ a day.
  • If you cross the International Date Line travelling west, today becomes tomorrow and you ‘lose’ a day.

The textbook even provided details on why Samoa changed time zones, losing a day, in 2011. I actually remember when this happened and made headlines, and of course I found it fascinating.


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