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The annual fall occurrence of Daylight Saving Time and the return in spring to standard time brings with it the biannual confusion of what time zones and countries do what and how many hours people in different parts of the world are from each other.
The most well-known time zone is Greenwich Mean Time which is considered the standard by which all other time zones are based after. Greenwich Time was established because the world needed a prime meridian location by which to conduct navigation, shipping, trade, and more. The Greenwich Meridian became the prime meridian used to establish a baseline for time that could then be used for timekeeping and navigational purposes around the world.
Greenwich Mean Time was first set up in 1675 by the Royal Observatory. The organization established the set time to assist sailors and mariners in navigation while at sea, as the method of doing so had been perfected by that time. By using the time and a few other navigational instruments sailors could accurately predict their location without needing to have a visible landmass nearby. Different cities within England and around the world still kept their local times.
Prior to the establishment of the Greenwich Mean Time the time of day would be calculated with a sun dial using solar time. This time would be different for every location but gave an accurate representation of the local time depending on where exactly in the world the sundial was being used. Once mechanical clocks and watches began gaining in popularity during the early 19th century there continued to be an increase in time standardization.
The gap between official time and solar time around the world. Map: Steffano Maggiolo.
The methods of establishing each time zone come down to determining factors regarding Earth’s orbit around the sun and the 24-hour day. By this reckoning each time zone is approximately 15 degrees wide. However, there is some disagreement on whether or not there are 24 or 25 time zones; the International Date Line is seen by some as a time zone, but not by others. There are standard time zones as well as non-standard ones, just to add some more confusion to the mix.
As with Daylight Savings Time there is no consistent universal agreement about the implementation of time zones. The International Date Line itself doesn’t run in a straight line at the request of some Pacific Island nations, who would be split down the middle by the date line. As one side of the line is one calendar day ahead of the other side this could cause difficulties in travel, trade, and economic functions just to name a few.
There are places with time line anomalies, like China. China is technically all under one time zone, but certain areas like Tibet and Xinjiang use a different time zone unofficially. China is 8 hours ahead of Greenwich Mean Time, and 6 hours ahead of Greenwich Mean Time in the case of Xinjiang and Tibet. China wasn’t always under one time zone, however; the country was formerly made up of 5 time zones that included GMT+5.5, GMT+6, GMT+7, GMT+8 and GMT+8.5. The half-hour increments create a non-standard time zone and aren’t uncommon around the world and are often used in some cities as the official local time. China created the uniform time zone in 1949 which applies to Taiwan, Hong Kong and Macau, despite the differences in jurisdiction and ownership of those territories.
While the massive nation of Russia spans nearly 10 time zones there are places in the world that don’t have time zones at all because of their location. Antarctica is one such example; because the continent sits on every line of longitude it is nearly impossible to pick one for its standard time. The extreme day-night cycles aren’t replicated anywhere else on the earth and therefore are unsuitable for use as a marker for what time zone Antarctica should be put in. Nations that lay claim to parts of Antarctica typically use the time zone of the host nation to make things easier. Less established scientific stations or territories do not have a time zone at all due to their lack of consistent use.
Time zones are a bit crazy, as anyone who has ever traveled around the world or even just a few miles away across a time zone marker knows. While time zones do make communication, travel and trade easier they aren’t always as consistent as we think they are. We can all rest in the knowledge that, thanks to time zones, it is always 5 o’clock somewhere.
References
Time and Date. A Brief History of Time Zones. 2014. Web November 2014. http://www.timeanddate.com/time/time-zones-history.html
World Atlas. International Date Line. 2014. Web November 2014. http://www.worldatlas.com/aatlas/infopage/dateline.htm
Wikipedia. Time in Antarctica. 2014. Web November 2014. http://en.wikipedia.org/wiki/Time_in_Antarctica
Wikipedia. Time in China. 2014. Web November 2014. http://en.wikipedia.org/wiki/Time_in_China