Time Zones: Why Do We Have Them?

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Today it is somewhat possible to talk to someone in the “future” or “past” – as long as they’re in a different time zone, that is.

Time zones are not something that receive a lot of thought in daily life, but they were created to implement more precision in worldwide timekeeping. This article on OnlineClock.net‘s Alarm Clock Blog will be dedicated to the methods and history of these time-dividing structure systems that we call time zones.

Greenwich Mean Time

Map showing where Greenwich, England is located.

Why Time Zones Were Created

Originally, the need for time zones arose in Britain when English mariners needed to know the longitude at sea. By dividing the world into several sections, or time zones, this was much more simple. When the first time zone division emerged, each zone was divided according to its local noon. This was also based on daylight hours, which vary in different parts of the world at a given second, based on the position of the Earth to the sun. Time zones were created to give a uniform standard of time, but at the original time of the first internationally recognized time zone’s emergence, various countries had their own time zone standards. According to reports from Greenwich Mean Time’s website, before the coming of railways to Britain, there was no need for each city to keep in sync with another city’s exact time. For example, the city of Bristol had their own different local time than London did. Before GMT became regulated as the first time zone standard, some pre-1880 British clocks had two minute hands; one to display the local time and the other to display Greenwich Mean Time.

Greenwich Royal Observatory in London

Greenwich Royal Observatory in London

Greenwich Mean Time

Time zones originated with Greenwich Mean Time. This well-known time authority is the mean solar time at the Greenwich Royal Observatory in London. A fact sheet called “This Week In Science,” published by The University of Maryland’s Library notes that Greenwich Mean Time, commonly shortened to GMT, was adopted by British Parliament in 1880 on August 2. Since 1676, Greenwich had been the national time center, initially designed to assist naval navigation. Later in 1883 at 12:00 p.m, the United States followed suit and adopted Greenwich Mean Time as their standard, also called civil time. Before adopting GMT, the United States included more than 300 different localized times. Greenwich Mean Time became the world’s civil time standard on November 1, 1884 after a meeting about time zones occurred in Washington, DC by the International Meridian Conference, remaining the civil time for almost a century.

NIST - National Institute of Standards and Technology

Logo for the National Institute of Standards and Technology

Coordinated Universal Time

The National Institute of Standards and Technology reported the new civil time system – Coordinated Universal Time, shortened to UTC, replaced GMT as the civil time standard. As NIST states, the new system emerged with the influence of atomic clocks and timekeeping. In 1967, the time element known as a second was re-evaluated and redefined for a more precise accuracy in time interval measurement. When tested with the standard of Greenwich Mean Time, it was not possible to make a connection in relation to the Earth’s rotation. For this reason, the UTC was formed and implemented internationally on January 1, 1972. Original time step templates for the new approved time zone standard were developed by Louis Essen in 1968. He is also credited with inventing the caesium atomic clock. The UTC time zone is coordinated with the atomic clock’s rate, however when time intervals and the Earth approaching one second do not match, a leap second, or one-second adjustment, is made to compensate. The NIST and USNO are the official providers of timekeeping for the United States, which may be seen on time.gov.

Daylight Savings Time: Spring Forward

Daylight Savings Time

Most people are familiar with this term, as it is a time standard adopted in most countries. According to the NIST, this includes setting clocks forward one hour around the beginning of the spring season, then setting them back one hour around the beginning of fall. Countries that are located in close proximity to the equator do not use this system, as their sunlight exposure is much more consistent and uniform than other regions of the world. An easy way to remember which way to set the clock to avoid confusion is “spring forward, fall back.” The idea for DST began in 1907 and was implemented during World War I as a way to conserve coal resources. Different countries across the world may have slightly different variations of DST. As noted on their report, NIST states clearly that they do not make the rules for Daylight Savings Time; these rules are made by the U.S Department of Transportation.

Daylight Savings Time: Fall Back

Nautical & Zulu Time Zones

Nautical time systems have been used since the 1920s for ships at sea. In this system, a one-hour time change is implemented for each 15° longitude change. The 15° that is off from GMT by 12 hours is divided by the nautical date by two 7.5° gores that are different from GMT by ±12 hours. A nautical date line is implied on maps, following the 180th meridian everywhere except territorial waters of land locations. Once a ship enters the territorial waters, they must then adapt that country’s civil time standard; changing of the clocks is usually done by the captain at his or her discretion. Zulu Time, according to the U.S Navy, is essentially the same as GMT, but “Zulu” is a term commonly used by the Navy for this system. The Navy states that its origin was due to the fact that as time accuracy need increased, the need for a base point increased too. From this need emerged the “prime meridian” – the beginning point of time base, which is where the Greenwich Observatory lies. The Navy uses the letter “Z,” pronounced “Zulu,” to refer to the prime meridian – this is where the term “Zulu Time” comes from.

Time Zones - U.S.A.

Map showing the various time zones for the United States of America.

Time Zone Facts For Various Countries

  • China once had 5 time zones; now it is the largest country having only one zone, which is UTC+08.
  • North America has 11 time zones – HST (Hawaii Standard), AKDST (Alaska Daylight), PDT (Pacific Daylight), MST (Mountain Standard), MDT (Mountain Daylight ), CST (Central Standard) SASK/CST (Saskachewan Central Standard), CDT (Central Daylight), EDT (Eastern Daylight), EST (Eastern Standard), ADT (Atlantic Daylight), AST (Atlantic Standard) and NDT (Newfoundland Daylight).
  • Europe uses several time zones among its 54 countries, including: UTC (Coordinated Universal Time), AZOST (Azores Summer), BST (British Summer), IST (Irish Summer), WEST (Western European Summer), Canary Islands, Portugal), CEST (Central European Summer), EEST (Eastern European Summer), MSKS (Moscow Summer)
  • There are 22 spots where more than 2 time zones meet in various countries of the world.
  • Russia is the country with the most time zones, having 11 in one country.

Did you know that OnlineClock.net functions perfectly for all time zones across the entire world? It does this by always using your computer’s internal time setting to display the current time on its various online clocks, timers, stopwatches and countdowns. This means: as long as your computer’s clock is set for the correct time zone, all of the various clocks on OnlineClock.net will also show you the correct time for where you’re located. If you ever do travel from one time zone to another, simply update your computer’s time settings for the new time zone where you’re located. OnlineClock.net will then instantly update itself to your computer’s changed time zone, thus showing you the correct time.

We hope we’ve shown that implementing an international time standard made business and travel more efficient globally.

Giving a whole new perspective to the past, present and future, these time zones govern our daily lives and keep us on track with time.

So, the next time you think it’s a bit difficult to keep track of the time due to many geographical places being located in different time zones, try to keep in mind that these time zones fulfill a very necessary role in managing global time-keeping for the entire planet!

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