December 7, 2021

I, Science

The science magazine of Imperial College

Why does Russia have 11 time zones while China has just one? Peter Sherman investigates the history, politics and technology behind some of the world’s most incongruous ways of telling time.

local time zones (South Yorkshire)

Humankind was once dependent on the location of the sun to determine the time of day. With the onset of rail transport and the telegraph, however, solar time quickly became obsolete. As people began travelling great distances in short periods of time, it became necessary to standardise local time scales.

Greenwich Mean Time (GMT) was initially established in 1675 for mariners at sea, but it took centuries to catch on as the standard time zone. Nowadays the world is partitioned into 24 standard time zones, which correspond to the 24 hours in each day. The time at any location is determined by its longitudinal proximity to Greenwich, London – every 15˚ in longitude alters the time by one hour.

Curioso elemento el tiempo LeoplusDespite this attempt at standardisation, for several historical and technological reasons time zones still come with their fair share of bizarrely interesting quirks.

Although India spans nearly three time zones, it observes only one uniform time zone, Indian Standard Time (IST = GMT+5.30), across the entire country. IST was originally created to simplify railway times countrywide in the 19th century. Due to the inefficiencies of having one time zone for a nation that covers nearly 3,000km longitudinally, eastern regions, like Assam, demand timezone reform.

Time zones in Russia  WonderWhy
Time zones in Russia compared with line of longitude. White number are the actual time zones, the black numbers represent the ‘ideal’ time zones going by lines of longitude.

While regions in India are looking to get ahead of the times (pun intended), Russia appears to be taking steps in the opposite direction. In early 2010 Vladimir Putin signed three decrees to abolish two of Russia’s 11 time zones in an attempt to unite other regions and increase business relations with Moscow. Putin may have taken this idea from China.

China Standard Time (CST = GMT+8.00) is used throughout all of China. From 1912 to 1949 China was divided into five separate time zones which, geographically speaking, made sense. Once the People’s Republic of China was established, however, the government abandoned all of the time zones, and sought to establish a single time zone based on Beijing time for the entire nation. This is especially problematic for cities in western China, such as Kashgar, where the sun typically sets at midnight CST.

In another example of time zone weirdness, Spain is an hour ahead of the UK despite the fact that the two nations are in the same 15˚ longitudinal gap. The reason for this discrepancy dates back to over seven decades ago, during World War II, when Spanish dictator Francisco Franco turned the clocks ahead an hour to match with their ally, Nazi Germany. Even though their time zone now seems outdated and nonsensical, Spain has yet to change it back to what it once was.

Well-known by most of Western civilisation is the infamous Daylight Savings Time (DST). The main purpose of DST is to start the day earlier, to correspond with the earlier rise of the sun in the spring and summer, which gives us more time awake in daylight. The process can be difficult to track as there are more countries that have not adopted DST than those that have. It is especially confusing in North America where there are regions of Canada, the US, and Mexico that have forgone DST while the rest of their nations have stayed put.

international date lineStrangest of all is the International Date Line, an imaginary line running through the Pacific Ocean that marks a difference of one calendar day depending on which side of the line you’re on. Travelling from west to east over the IDL moves you ahead one full day, and vice versa for east to west.

While time zones can be bring about some confusion, they are a necessary evil for a world that is more interconnected than ever before.

Peter Sherman is a second year undergraduate studying Physics

Images: South Yorkshire time zones by Edwyn Anderton; Curioso elemento el tiempo by Leoplus; Time zones in Russia compared with lines of longitude by WonderWhy; Time Zones at the International Date Line by WonderWhy