Lines Of longtitude & The World's Time Zones

A line of longtitude is an imaginary, vertical line which connects locations on a map. A locational position can then be determined along with the line of longtitude's opposite counterpart, a line of latitude. Lines of longtitude, also known as parallels, because they run parallel to one other, start at 0 degrees and travel east or west along a map at intervals of 15 degrees. Each line starts at the North Pole and radiates south towards the South Pole covering half the great circle of the earth, which measures 20,003,093 kms.There are two major lines of longtitude, the Prime Meridian situated at 0 degrees and the International Date Line situated half a globe away at 180 degrees, where it is also known as the 180th Parallel.

These lines determine the globe's time zones, which are ultimately determined by the Sun and it's relative position to the earth.


The word meridian comes from the Latin for midday, hence the use of the terms AM ( ante meridian = morning) and PM (post meridian = afternoon) with the 12 hour clock.

The Prime Meridian is located on a map at 0 degrees, which is situated radiating from the North Pole down towards the South Pole. The Prime Meridian was adopted in 1884 at the International Meridian Conference and the location chosen for it was The Royal Observatory at Greenwich in London, England due to the country's long and distinguished naval history. This heralded the start of the world's time zones being determined by GMT ( Greenwich Mean Time), which has since been superceded by UTC ( Co-ordinated Universal Time).

The Prime Meridian divides the globe into it's Western and Eastern Hemispheres and, along with it's opposte counterpart the 180th Parallel, ultimately determines the planet's international time zones and dates.

Countries situated along the Prime Meridian are; Algeria, Burkina Faso, France, Ghana, Mali, Spain, Togo, United Kingdom.


The International Date Line, also known as the 180th Parallel, is an imaginary line situated roughly in the centre of the Pacific Ocean, which determines the place on earth where each new calendar day ( 24 hour period) begins. It is a fixed, albeit arbitrary, boundary on the globe which was drawn with certain diversions - unlike the Prime Meridian it is not in a straight line - to pass around certain territories and islands.

Travelling from east to west, one hour is lost every 15 degrees of longtitude, this is symbolised for the purpose of time keeping, by the minus sign.

Travelling from west to east, one hour is gained every 15 degrees of longtitude, this is symbolised, for the purpose of time keeping, by the plus sign.

Kiribati's Line Islands in the Pacific Ocean are the most easterly land mass from the Prime Meridian and therefore have the most advanced time of + 14 hours, that means that they are located at plus (in front of ) 14 hours or fourteen lines of longtitude, from the Prime Meridian. The time of day in the Line Islands is exactly the same time as in Hawaii, but the date is one day ahead.

Attu Island in the the Aleutian Islands of the North Pacific, situated about 60 kms from the International Date Line, is the location of the most westerly land mass from the Prime Meridian and is situated on time zone - 11, meaning that it is located eleven hours minus (behind) or eleven lines of longtitude, from the Prime Meridian.

This imaginary line does not touch upon on any areas of land, but is instead, situated between certain land points, these are ;

From north to south running east of -

Russia's Wrangel Island and Chuchki Peninsula and further south to Russia's Commander Islands, continuing south to divide the Diomede Islands, further south to circumscribe the far east of the island of Kiribati, almost to the 150th parallel, and then back on course to run east of the island of Wallis and Futuna Islands, Samoa, Tokelau, Fiji, Tonga and New Zealand's Kermadec Island and the Chatham Islands.

From north to south running west of -

Alaska's St Lawrence and St Mathew Islands, further south to west of Alaska's Aleutian Island of Attu Island, continuing south to The U.S Islands of Hawaii and then continuing on to the west of Baker and Howland Islands in the United States Minor Outlying Islands, Tahiti, American Samoa, Niue and the Cook Islands.


There are countries however, which although lie physically or geographically on one particular time zone, actually use a different time zone, such as France and Spain which use Western European Time, and eight countries / territories which use UTC, which should geographically use UTC + 1, these countries / territories are;

Azores - Portugal - Canary Islands, Spain - Faroe Islands, Denmark - Iceland - Madeira, Portugal - Outer Hebrides, Scotland - tristan Da Cunha Archipelago, United Kingdom Overseas Territory.

The UTC's most easterly point on a map is Suffolk in England and it's most westerly point on a map is Isafjordur in Iceland.

A country's Standard Time can also differ by way of using Summer Time or Daylight Saving Time, which is used by various countries around the world, particularly those in the Northern Hemisphere.

One country which uses UTC , but is not physically / geographically situated on UTC, and uses neither Daylight Saving Time or Summer Time is Iceland, whose time is often used to regulate and configure electronic devices, due to the fact that it's time remains unchanged throughout the year.


There are twenty four time zones in the world. Below are the countries, along with the names of their individual time zones, which, due to their vast size, have the most standard time zones in the world.

RUSSIAN FEDERATION - 9 - Kalingrad, Moscow, Ekaterinburg, Omsk, Krasnoyarsk, Irkutsk, Yakutsk, Vladivostock and Magadan - From UTC + 3 to UTC + 12. Daylight Saving Time is observed.

UNITED STATES - 6 - Eastern, Central, Mountain, Pacific, Alaskan and Hawaiin / Aleutian - The contigious states are set at UTC - 5 to UTC - 8 , and the non contigious states are set at UTC - 9 to UTC - 11. Daylight Saving Time is observed

CANADA - 6 - Newfoundland, Atlantic, Eastern, Central, Mountain and Pacific - From UTC - 3.5 to UTC - 8. Daylight Saving Time is observed.

BRAZIL - 4 - Acre, Amazonas, Eastern and Fernando de Noronha - From UTC - 3 to UTC - 5. Daylight Saving Time is observed only in southern Brazil.

GREENAND- 4 - East, West, Central and Danmarkhavn - From UTC - 1 to UTC - 4. Daylight Saving Time is observed.

AUSTRALIA - 3 - Eastern Standard Time (EST), Central Standard Time (CST) and Western Standard Time (WST) - From UTC + 8 to UTC + 10. Daylight Saving Time is observed.

MEXICO - 3 - Central, Mountain and Pacific - From UTC - 6 to UTC - 8. Daylight Saving Time is observed.

* FRANCE - Theoretically France has the most time zones of any country in the world, as France considers all of it's outlying territories as regions of it's mainland. Therefore with mainland France situated on UTC - 1 and it's most far reaching territory of New Caledonia situated on UTC + 11, France actually spans twelve time zones.

** CHINA - 1 - Geographically China spans five time zones, but the whole country actually uses just the one, China Standard Time (CST). The administration districts of Hong Kong, Macau and Taiwan, although having their own time zone names, are also on the same time as China, all of which are UTC + 8 and non of which use Summer Time or Daylight Saving Time.

*** INDIA - 1 - Geographically India spans two time zones, but the whole country actually uses only one, India Standard Time (IST), which is set at UTC + 5.5, which uses neither Summer Time nor Daylight Saving Time.


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