Time zone

Time zones of the world

A time zone is an area that observes a uniform standard time for legal, commercial and social purposes. Time zones tend to follow the boundaries between countries and their subdivisions instead of strictly following longitude, because it is convenient for areas in frequent communication to keep the same time.

All time zones are defined as offsets from Coordinated Universal Time (UTC), ranging from UTC−12:00 to UTC+14:00. The offsets are usually a whole number of hours, but a few zones are offset by an additional 30 or 45 minutes, such as in India, South Australia and Nepal.

Some areas of higher latitude use daylight saving time for about half of the year, typically by adding one hour to local time during spring and summer.

List of UTC offsets

Time zones of the world

In the table below, the locations that use daylight saving time (DST) are listed in their UTC offset when DST is not in effect. When DST is in effect, approximately during spring and summer, their UTC offset is increased by one hour (except for Lord Howe Island, where it is increased by 30 minutes). For example, during the DST period California observes UTC−07:00 and the United Kingdom observes UTC+01:00.

UTC offsetLocations that do not use DSTLocations that use DST
UTC−12:00 Baker Island Howland Island
UTC−11:00 American Samoa
 Jarvis Island
 Kingman Reef
 Midway Atoll
 Niue
 Palmyra Atoll
UTC−10:00 Cook Islands
 French Polynesia (most)
 Johnston Atoll
 United States: Hawaii
 United States: Andreanof Islands, Islands of Four Mountains, Near Islands, Rat Islands (Aleutian Islands, Alaska)
UTC−09:30 French Polynesia: Marquesas Islands
UTC−09:00 French Polynesia: Gambier Islands United States: Alaska (most)
UTC−08:00 Clipperton Island
 Pitcairn Islands
 Canada: British Columbia (most)
 Mexico: Baja California
 United States: California, Idaho (north), Nevada (most), Oregon (most), Washington
UTC−07:00 Canada: British Columbia (northeast), Yukon
 Mexico: Sonora
 United States: Arizona (most)
 Canada: Alberta, British Columbia (southeast), Northwest Territories, Nunavut (west)
 Mexico: Baja California Sur, Chihuahua, Nayarit (most), Sinaloa
 United States: Colorado, Idaho (most), Montana, New Mexico, Utah, Wyoming
UTC−06:00 Belize
 Canada: Saskatchewan (most)
 Costa Rica
 Ecuador: Galápagos
 El Salvador
 Guatemala
 Honduras
 Nicaragua
 Canada: Manitoba, Nunavut (central), Ontario (west)
 Chile: Easter Island
 Mexico (most)
 United States: Alabama, Arkansas, Illinois, Iowa, Kansas (most), Louisiana, Minnesota, Mississippi, Missouri, Nebraska (most), North Dakota (most), Oklahoma, South Dakota (most), Tennessee (most), Texas (most), Wisconsin
UTC−05:00 Brazil: Acre
 Canada: Atikokan, Mishkeegogamang, Southampton Island
 Cayman Islands
 Colombia
 Ecuador (most)
 Jamaica
 Mexico: Quintana Roo
 Navassa Island
 Panama
 Peru
 Bahamas
 Canada: Nunavut (east), Ontario (most), Quebec (most)
 Cuba
 Haiti
 Turks and Caicos Islands
 United States: Connecticut, Delaware, District of Columbia, Florida (most), Georgia, Indiana (most), Kentucky (most), Maine, Maryland, Massachusetts, Michigan (most), New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Vermont, Virginia, West Virginia
UTC−04:00 Anguilla
 Antigua and Barbuda
 Aruba
 Barbados
 Bolivia
 Brazil: Amazonas (most), Mato Grosso, Mato Grosso do Sul, Rondônia, Roraima
 British Virgin Islands
 Canada: Quebec (east)
 Caribbean Netherlands
 Curaçao
 Dominica
 Dominican Republic
 Grenada
 Guadeloupe
 Guyana
 Martinique
 Montserrat
 Puerto Rico
 Saint Barthélemy
 Saint Kitts and Nevis
 Saint Lucia
 Saint Martin
 Saint Vincent and the Grenadines
 Sint Maarten
 Trinidad and Tobago
 U.S. Virgin Islands
 Venezuela
 Bermuda
 Canada: Labrador (most), New Brunswick, Nova Scotia, Prince Edward Island
 Chile (most)
 Greenland: Thule Air Base
 Paraguay
UTC−03:30 Canada: Newfoundland, Labrador (southeast)
UTC−03:00 Argentina
 Brazil (most)
 Chile: Magallanes
 Falkland Islands
 French Guiana
 Suriname
 Uruguay
 Greenland (most)
 Saint Pierre and Miquelon
UTC−02:00 Brazil: Fernando de Noronha
 South Georgia and the South Sandwich Islands
UTC−01:00 Cape Verde Greenland: Ittoqqortoormiit
 Portugal: Azores
UTC±00:00 Burkina Faso
 Gambia
 Ghana
 Greenland: Danmarkshavn
 Guinea
 Guinea-Bissau
 Iceland
 Ivory Coast
 Liberia
 Mali
 Mauritania
 Saint Helena, Ascension and Tristan da Cunha
 Senegal
 Sierra Leone
 São Tomé and Príncipe
 Togo
 Faroe Islands
 Guernsey
 Ireland
 Isle of Man
 Jersey
 Portugal (most)
 Spain: Canary Islands
 United Kingdom
UTC+01:00 Algeria
 Angola
 Benin
 Cameroon
 Central African Republic
 Chad
 Congo
 Democratic Republic of the Congo: Équateur, Kinshasa, Kongo Central, Kwango, Kwilu, Mai-Ndombe, Mongala, Nord-Ubangi, Sud-Ubangi, Tshuapa
 Equatorial Guinea
 Gabon
 Morocco[a]
 Niger
 Nigeria
 Tunisia
 Western Sahara[a]
 Albania
 Andorra
 Austria
 Belgium
 Bosnia and Herzegovina
 Croatia
 Czech Republic
 Denmark
 France (metropolitan)
 Germany
 Gibraltar
 Hungary
 Italy
 Kosovo
 Liechtenstein
 Luxembourg
 Malta
 Monaco
 Montenegro
 Netherlands (European)
 North Macedonia
 Norway
 Poland
 San Marino
 Serbia
 Slovakia
 Slovenia
 Spain (most)
 Sweden
 Switzerland
  Vatican City
UTC+02:00 Botswana
 Burundi
 Democratic Republic of the Congo (most)
 Egypt
 Eswatini
 Lesotho
 Libya
 Malawi
 Mozambique
 Namibia
 Russia: Kaliningrad
 Rwanda
 South Africa (most)
 South Sudan
 Sudan
 Zambia
 Zimbabwe
 Akrotiri and Dhekelia
 Bulgaria
 Cyprus
 Estonia
 Finland
 Greece
 Israel
 Jordan
 Latvia
 Lebanon
 Lithuania
 Moldova
 Northern Cyprus
 Palestine
 Romania
 Transnistria
 Syria
 Ukraine (most)
UTC+03:00 Abkhazia
 Bahrain
 Belarus
 Comoros
 Djibouti
 Eritrea
 Ethiopia
 French Southern and Antarctic Lands: Scattered Islands[4]
 Iraq
 Kenya
 Kuwait
 Madagascar
 Mayotte
 Qatar
 Russia (most of European part)
 Saudi Arabia
 Somalia
 Somaliland
 South Africa: Prince Edward Islands
 South Ossetia
 Tanzania
 Turkey
 Uganda
 Ukraine: occupied territories
 Yemen
UTC+03:30 Iran
UTC+04:00 Armenia
 Azerbaijan
 French Southern and Antarctic Lands: Crozet Islands[4]
 Georgia
 Mauritius
 Oman
 Russia: Astrakhan, Samara, Saratov, Udmurtia, Ulyanovsk
 Réunion
 Seychelles
 United Arab Emirates
UTC+04:30 Afghanistan
UTC+05:00 French Southern and Antarctic Lands: Kerguelen Islands, Saint Paul Island, Amsterdam Island
 Heard Island and McDonald Islands
 Kazakhstan: Aktobe, Atyrau, Baikonur, Kyzylorda, Mangystau, West Kazakhstan
 Maldives
 Pakistan
 Russia: Bashkortostan, Chelyabinsk, Khanty-Mansi, Kurgan, Orenburg, Perm, Sverdlovsk, Tyumen, Yamalia
 Tajikistan
 Turkmenistan
 Uzbekistan
UTC+05:30 India
 Sri Lanka
UTC+05:45 Nepal
UTC+06:00 Bangladesh
 Bhutan
 British Indian Ocean Territory
 Kazakhstan (most)
 Kyrgyzstan
 Russia: Omsk
UTC+06:30 Cocos Islands
 Myanmar
UTC+07:00 Cambodia
 Christmas Island
 Indonesia: Sumatra, Java, West Kalimantan, Central Kalimantan
 Laos
 Mongolia: Bayan-Ölgii, Khovd, Uvs
 Russia: Altai Krai, Altai Republic, Kemerovo, Khakassia, Krasnoyarsk, Novosibirsk, Tomsk, Tuva
 Thailand
 Vietnam
UTC+08:00 Australia: Western Australia (most)
 Brunei
 China
 Hong Kong
 Indonesia: South Kalimantan, East Kalimantan, North Kalimantan, Sulawesi, Bali, West Nusa Tenggara, East Nusa Tenggara
 Macau
 Malaysia
 Mongolia (most)
 Philippines
 Russia: Buryatia, Irkutsk
 Singapore
 Taiwan
UTC+08:45 Australia: Eucla
UTC+09:00 East Timor
 Indonesia: Maluku, North Maluku, Papua, West Papua
 Japan
 North Korea
 Palau
 Russia: Amur, Sakha (most), Zabaykalsky
 South Korea
UTC+09:30 Australia: Northern Territory Australia: South Australia
UTC+10:00 Australia: Queensland
 Guam
 Micronesia: Chuuk, Yap
 Northern Mariana Islands
 Papua New Guinea (most)
 Russia: Jewish, Khabarovsk, Primorsky, Sakha (central-east)
 Australia: Australian Capital Territory, Jervis Bay Territory, New South Wales (most), Tasmania, Victoria
UTC+10:30 Australia: Lord Howe Island
UTC+11:00 Micronesia: Kosrae, Pohnpei
 New Caledonia
 Papua New Guinea: Bougainville
 Russia: Magadan, Sakha (east), Sakhalin
 Solomon Islands
 Vanuatu
 Norfolk Island
UTC+12:00 Fiji
 Kiribati: Gilbert Islands
 Marshall Islands
 Nauru
 Russia: Chukotka, Kamchatka
 Tuvalu
 Wake Island
 Wallis and Futuna
 New Zealand (most)
UTC+12:45 New Zealand: Chatham Islands
UTC+13:00 Kiribati: Phoenix Islands
 Samoa
 Tokelau
 Tonga
UTC+14:00 Kiribati: Line Islands
  1. ^ a b Observes UTC±00:00 around Ramadan.[1][2][3]

History

The apparent position of the Sun in the sky, and thus solar time, varies by location due to the spherical shape of the Earth. This variation corresponds to four minutes of time for every degree of longitude, so for example when it is solar noon in London, it is about 10 minutes before solar noon in Bristol, which is about 2.5 degrees to the west.[5]

The Royal Observatory, Greenwich, founded in 1675, established Greenwich Mean Time (GMT), the mean solar time at that location, as an aid to mariners to determine longitude at sea, providing a standard reference time while each location in England kept a different time.

Railway time

Plaque commemorating the Railway General Time Convention of 1883 in North America
The control panel of the Time Zone Clock in front of Coventry Transport Museum

In the 19th century, as transportation and telecommunications improved, it became increasingly inconvenient for each location to observe its own solar time. In November 1840, the Great Western Railway started using GMT kept by portable chronometers.[6] This practice was soon followed by other railway companies in Great Britain and became known as Railway Time.

Around August 23, 1852, time signals were first transmitted by telegraph from the Royal Observatory. By 1855, 98% of Great Britain's public clocks were using GMT, but it was not made the island's legal time until August 2, 1880. Some British clocks from this period have two minute hands, one for the local time and one for GMT.[7]

On November 2, 1868, the then British Colony of New Zealand officially adopted a standard time to be observed throughout the colony.[8] It was based on longitude 172°30′ east of Greenwich, that is 11 hours 30 minutes ahead of GMT. This standard was known as New Zealand Mean Time.[9]

Timekeeping on North American railroads in the 19th century was complex. Each railroad used its own standard time, usually based on the local time of its headquarters or most important terminus, and the railroad's train schedules were published using its own time. Some junctions served by several railroads had a clock for each railroad, each showing a different time.[10]

1913 time zone map of the United States, showing boundaries very different from today

Charles F. Dowd proposed a system of hourly standard time zones for North American railroads around 1863, although he published nothing on the matter at that time and did not consult railroad officials until 1869. In 1870 he proposed four ideal time zones having north–south borders, the first centered on Washington, D.C., but by 1872 the first was centered on meridian 75° west of Greenwich, with natural borders such as sections of the Appalachian Mountains. Dowd's system was never accepted by North American railroads. Instead, U.S. and Canadian railroads implemented a version proposed by William F. Allen, the editor of the Traveler's Official Railway Guide.[11] The borders of its time zones ran through railroad stations, often in major cities. For example, the border between its Eastern and Central time zones ran through Detroit, Buffalo, Pittsburgh, Atlanta, and Charleston. It was inaugurated on Sunday, November 18, 1883, also called "The Day of Two Noons",[12] when each railroad station clock was reset as standard-time noon was reached within each time zone.

The North American zones were named Intercolonial, Eastern, Central, Mountain, and Pacific. Within a year 85% of all cities with populations over 10,000 (about 200 cities) were using standard time.[13] A notable exception was Detroit (located about halfway between the meridians of Eastern and Central time), which kept local time until 1900, then tried Central Standard Time, local mean time, and Eastern Standard Time (EST) before a May 1915 ordinance settled on EST and was ratified by popular vote in August 1916. The confusion of times came to an end when standard time zones were formally adopted by the U.S. Congress in the Standard Time Act of March 19, 1918.

Worldwide time zones

Italian mathematician Quirico Filopanti introduced the idea of a worldwide system of time zones in his book Miranda!, published in 1858. He proposed 24 hourly time zones, which he called "longitudinal days", the first centred on the meridian of Rome. He also proposed a universal time to be used in astronomy and telegraphy. However, his book attracted no attention until long after his death.[14][15]

Scottish-born Canadian Sir Sandford Fleming proposed a worldwide system of time zones in 1876 - see Sandford Fleming § Inventor of worldwide standard time. The proposal divided the world into twenty-four time zones labeled A-Y (skipping J), each one covering 15 degrees of longitude. All clocks within each zone would be set to the same time as the others, but differed by one hour from those in the neighboring zones.[16] He advocated his system at several international conferences, including the International Meridian Conference, where it received some consideration. The system has not been directly adopted, but some maps divide the world into 24 time zones and assign letters to them, similarly to Fleming's system.[17]

World map of time zones in 1928

By about 1900, almost all inhabited places on Earth had adopted a standard time zone, but only some of them used an hourly offset from GMT. Many applied the time at a local astronomical observatory to an entire country, without any reference to GMT. It took many decades before all time zones were based on some standard offset from GMT or Coordinated Universal Time (UTC). By 1929, the majority of countries had adopted hourly time zones, though some countries such as Iran, India and parts of Australia had time zones with a 30-minute offset. Nepal was the last country to adopt a standard offset, shifting slightly to UTC+05:45 in 1986.[18]

All nations currently use standard time zones for secular purposes, but not all of them apply the concept as originally conceived. Several countries and subdivisions use half-hour or quarter-hour deviations from standard time. Some countries, such as China and India, use a single time zone even though the extent of their territory far exceeds the ideal 15° of longitude for one hour; other countries, such as Spain and Argentina, use standard hour-based offsets, but not necessarily those that would be determined by their geographical location. The consequences, in some areas, can affect the lives of local citizens, and in extreme cases contribute to larger political issues, such as in the western reaches of China.[19] In Russia, which has 11 time zones, two time zones were removed in 2010[20][21] and reinstated in 2014.[22]

Notation

ISO 8601

ISO 8601 is a standard established by the International Organization for Standardization defining methods of representing dates and times in textual form, including specifications for representing time zones.[23]

If a time is in Coordinated Universal Time (UTC), a "Z" is added directly after the time without a separating space. "Z" is the zone designator for the zero UTC offset. "09:30 UTC" is therefore represented as "09:30Z" or "0930Z". Likewise, "14:45:15 UTC" is written as "14:45:15Z" or "144515Z".[24] UTC time is also known as "Zulu" time, since "Zulu" is a phonetic alphabet code word for the letter "Z".[24]

Offsets from UTC are written in the format ±hh:mm, ±hhmm, or ±hh (either hours ahead or behind UTC). For example, if the time being described is one hour ahead of UTC (such as the time in Germany during the winter), the zone designator would be "+01:00", "+0100", or simply "+01". This numeric representation of time zones is appended to local times in the same way that alphabetic time zone abbreviations (or "Z", as above) are appended. The offset from UTC changes with daylight saving time, e.g. a time offset in Chicago, which is in the North American Central Time Zone, is "−06:00" for the winter (Central Standard Time) and "−05:00" for the summer (Central Daylight Time).[25]

Abbreviations

Time zones are often represented by alphabetic abbreviations such as "EST", "WST", and "CST", but these are not part of the international time and date standard ISO 8601. Such designations can be ambiguous; for example, "CST" can mean (North American) Central Standard Time (UTC−06:00), Cuba Standard Time (UTC−05:00) and China Standard Time (UTC+08:00), and it is also a widely used variant of ACST (Australian Central Standard Time, UTC+09:30).[26]

Conversions

Conversion between time zones obeys the relationship

"time in zone A" − "UTC offset for zone A" = "time in zone B" − "UTC offset for zone B",

in which each side of the equation is equivalent to UTC.

The conversion equation can be rearranged to

"time in zone B" = "time in zone A" − "UTC offset for zone A" + "UTC offset for zone B".

For example, the New York Stock Exchange opens at 09:30 (EST, UTC offset= −05:00). In California (PST, UTC offset= −08:00) and India (IST, UTC offset= +05:30), the New York Stock Exchange opens at

time in California = 09:30 − (−05:00) + (−08:00) = 06:30;
time in India = 09:30 − (−05:00) + (+05:30) = 20:00.

These calculations become more complicated near the time switch to or from daylight saving time, as the UTC offset for the area becomes a function of UTC time.

The time differences may also result in different dates. For example, when it is 22:00 on Monday in Egypt (UTC+02:00), it is 01:00 on Tuesday in Pakistan (UTC+05:00).

The table "Time of day by zone" gives an overview on the time relations between different zones.

Nautical time zones

Since the 1920s, a nautical standard time system has been in operation for ships on the high seas. As an ideal form of the terrestrial time zone system, nautical time zones consist of gores of 15° offset from GMT by a whole number of hours. A nautical date line follows the 180th meridian, bisecting one 15° gore into two 7.5° gores that differ from GMT by ±12 hours.[27][28][29]

However, in practice each ship may choose what time to observe at each location. Ships may decide to adjust their clocks at a convenient time, usually at night, not exactly when they cross a certain longitude.[30] Some ships simply remain on the time of the departing port during the whole trip.[31]

Skewing of time zones

Difference between sun time and clock time during daylight saving time:
1h ± 30 min behind
0h ± 30m
1h ± 30 m ahead
2h ± 30 m ahead
3h ± 30 m ahead
  DST observed
  DST formerly observed
  DST never observed

Ideal time zones, such as nautical time zones, are based on the mean solar time of a particular meridian located in the middle of that zone with boundaries located 7.5 degrees east and west of the meridian. In practice, however, many time zone boundaries are drawn much farther to the west, and some countries are located entirely outside their ideal time zones.

For example, even though the Prime Meridian (0°) passes through Spain and France, they use the mean solar time of 15 degrees east (Central European Time) rather than 0 degrees (Greenwich Mean Time). France previously used GMT, but was switched to CET (Central European Time) during the German occupation of the country during World War II and did not switch back after the war.[32] Similarly, prior to World War II, the Netherlands observed "Amsterdam Time", which was twenty minutes ahead of Greenwich Mean Time. They were obliged to follow German time during the war, and kept it thereafter. In the mid-1970s the Netherlands, as other European states, began observing daylight saving (summer) time.

One reason to draw time zone boundaries far to the west of their ideal meridians is to allow the more efficient use of sunlight.[33] Some of these locations also use daylight saving time (DST), further increasing the difference to local solar time. As a result, in summer, solar noon in the Spanish city of Vigo occurs at 14:41 clock time. This westernmost area of continental Spain never experiences sunset before 18:00 clock time, even in winter, despite lying 42 degrees north of the equator.[34] Near the summer solstice, Vigo has sunset times after 22:00, similar to those of Stockholm, which is in the same time zone and 17 degrees farther north. Stockholm has much earlier sunrises, though.[35]

A more extreme example is Nome, Alaska, which is at 165°24′W longitude – just west of center of the idealized Samoa Time Zone (165°W). Nevertheless, Nome observes Alaska Time (135°W) with DST so it is slightly more than two hours ahead of the sun in winter and over three in summer.[36] Kotzebue, Alaska, also near the same meridian but north of the Arctic Circle, has two sunsets on the same day in early August, one shortly after midnight at the start of the day, and the other shortly before midnight at the end of the day.[37]

China extends as far west as 73°E, but all parts of it use UTC+08:00 (120°E), so solar "noon" can occur as late as 15:00 in western portions of China such as Xinjiang.[38] The Afghanistan-China border marks the greatest terrestrial time zone difference on Earth, with a 3.5 hour difference between Afghanistan's UTC+4:30 and China's UTC+08:00.

A visualization of the mismatch between clock time and solar time in different locations. In blue areas, clock time lags behind solar time; in red areas, the reverse is true. The two are synchronized in the white areas.

Daylight saving time

Many countries, and sometimes just certain regions of countries, adopt daylight saving time (DST), also known as summer time, during part of the year. This typically involves advancing clocks by an hour near the start of spring and adjusting back in autumn ("spring forward", "fall back"). Modern DST was first proposed in 1907 and was in widespread use in 1916 as a wartime measure aimed at conserving coal. Despite controversy, many countries have used it off and on since then; details vary by location and change occasionally. Countries around the equator usually do not observe daylight saving time, since the seasonal difference in sunlight there is minimal.

Computer systems

Many computer operating systems include the necessary support for working with all (or almost all) possible local times based on the various time zones. Internally, operating systems typically use UTC as their basic time-keeping standard, while providing services for converting local times to and from UTC, and also the ability to automatically change local time conversions at the start and end of daylight saving time in the various time zones. (See the article on daylight saving time for more details on this aspect).

Web servers presenting web pages primarily for an audience in a single time zone or a limited range of time zones typically show times as a local time, perhaps with UTC time in brackets. More internationally oriented websites may show times in UTC only or using an arbitrary time zone. For example, the international English-language version of CNN includes GMT and Hong Kong Time,[39] whereas the US version shows Eastern Time.[40] US Eastern Time and Pacific Time are also used fairly commonly on many US-based English-language websites with global readership. The format is typically based in the W3C Note "datetime".

Email systems and other messaging systems (IRC chat, etc.)[41] time-stamp messages using UTC, or else include the sender's time zone as part of the message, allowing the receiving program to display the message's date and time of sending in the recipient's local time.

Database records that include a time stamp typically use UTC, especially when the database is part of a system that spans multiple time zones. The use of local time for time-stamping records is not recommended for time zones that implement daylight saving time because once a year there is a one-hour period when local times are ambiguous.

Calendar systems nowadays usually tie their time stamps to UTC, and show them differently on computers that are in different time zones. That works when having telephone or internet meetings. It works less well when travelling, because the calendar events are assumed to take place in the time zone the computer or smartphone was on when creating the event. The event can be shown at the wrong time. For example, if a New Yorker plans to meet someone in Los Angeles at 9 AM, and makes a calendar entry at 9 AM (which the computer assumes is New York time), the calendar entry will be at 6 AM if taking the computer's time zone. There is also an option in newer versions of Microsoft Outlook to enter the time zone in which an event will happen, but often not in other calendar systems. Calendaring software must also deal with daylight saving time (DST). If, for political reasons, the begin and end dates of daylight saving time are changed, calendar entries should stay the same in local time, even though they may shift in UTC time. In Microsoft Outlook, time stamps are therefore stored and communicated without DST offsets.[42] Hence, an appointment in London at noon in the summer will be represented as 12:00 (UTC+00:00) even though the event will actually take place at 13:00 UTC. In Google Calendar, calendar events are stored in UTC (although shown in local time) and might be changed by a time-zone changes,[43] although normal daylight saving start and end are compensated for (similar to much other calendar software).

Operating systems

Unix

Most Unix-like systems, including Linux and Mac OS X, keep system time in time_t format, representing the number of seconds (excluding leap seconds) that have elapsed since 00:00:00 Coordinated Universal Time (UTC) on Thursday, January 1, 1970.[44] By default the external representation is as UTC (Coordinated Universal Time), though individual processes can specify time zones using the TZ environment variable.[45] This allows users in multiple time zones to use the same computer, with their respective local times displayed correctly to each user. Time zone information most commonly comes from the IANA time zone database. In fact, many systems, including anything using the GNU C Library, can make use of this database.

Microsoft Windows

Windows-based computer systems prior to Windows 2000 used local time, but Windows 2000 and later can use UTC as the basic system time.[46] The system registry contains time zone information that includes the offset from UTC and rules that indicate the start and end dates for daylight saving in each zone. Interaction with the user normally uses local time, and application software is able to calculate the time in various zones. Terminal Servers allow remote computers to redirect their time zone settings to the Terminal Server so that users see the correct time for their time zone in their desktop/application sessions. Terminal Services uses the server base time on the Terminal Server and the client time zone information to calculate the time in the session.

Programming languages

Java

While most application software will use the underlying operating system for time zone information, the Java Platform, from version 1.3.1, has maintained its own time zone database. This database is updated whenever time zone rules change. Oracle provides an updater tool for this purpose.[47]

As an alternative to the time zone information bundled with the Java Platform, programmers may choose to use the Joda-Time library.[48] This library includes its own time zone data based on the IANA time zone database.[49]

As of Java 8 there is a new date and time API that can help with converting time zones. Java 8 Date Time

JavaScript

Traditionally, there was very little in the way of time zone support for JavaScript. Essentially the programmer had to extract the UTC offset by instantiating a time object, getting a GMT time from it, and differencing the two. This does not provide a solution for more complex daylight saving variations, such as divergent DST directions between northern and southern hemispheres.

ECMA-402, the standard on Internationalization API for JavaScript, provides ways of formatting Time Zones.[50] However, due to size constraint, some implementations or distributions do not include it.[51]

Perl

The DateTime object in Perl supports all time zones in the Olson DB and includes the ability to get, set and convert between time zones.[52]

PHP

The DateTime objects and related functions have been compiled into the PHP core since 5.2. This includes the ability to get and set the default script time zone, and DateTime is aware of its own time zone internally. PHP.net provides extensive documentation on this.[53] As noted there, the most current time zone database can be implemented via the PECL timezonedb.

Python

The standard module datetime included with Python stores and operates on the time zone information class tzinfo. The third party pytz module provides access to the full IANA time zone database.[54] Negated time zone offset in seconds is stored time.timezone and time.altzone attributes. From Python 3.9, the zoneinfo module introduces timezone management without need for third party module.[55]

Smalltalk

Each Smalltalk dialect comes with its own built-in classes for dates, times and timestamps, only a few of which implement the DateAndTime and Duration classes as specified by the ANSI Smalltalk Standard. VisualWorks provides a TimeZone class that supports up to two annually recurring offset transitions, which are assumed to apply to all years (same behavior as Windows time zones). Squeak provides a Timezone class that does not support any offset transitions. Dolphin Smalltalk does not support time zones at all.

For full support of the tz database (zoneinfo) in a Smalltalk application (including support for any number of annually recurring offset transitions, and support for different intra-year offset transition rules in different years) the third-party, open-source, ANSI-Smalltalk-compliant Chronos Date/Time Library is available for use with any of the following Smalltalk dialects: VisualWorks, Squeak, Gemstone, or Dolphin.[56]

Time in outer space

Orbiting spacecraft may experience many sunrises and sunsets, or none, in a 24-hour period. Therefore, it is not possible to calibrate the time with respect to the Sun and still respect a 24-hour sleep/wake cycle. A common practice for space exploration is to use the Earth-based time of the launch site or mission control, synchronizing the sleeping cycles of the crew and controllers. The International Space Station normally uses Greenwich Mean Time (GMT).[57][58]

Timekeeping on Mars can be more complex, since the planet has a solar day of approximately 24 hours and 40 minutes, known as a sol. Earth controllers for some Mars missions have synchronized their sleep/wake cycles with the Martian day, because solar-powered rover activity on the surface was tied to periods of light and dark.[59]

See also

References

  1. ^ Morocco Re-Introduces Clock Changes for Ramadan 2019 Archived December 28, 2020, at the Wayback Machine, Timeanddate.com, April 19, 2019.
  2. ^ Time Zone in Casablanca, Morocco Archived March 30, 2021, at the Wayback Machine, Timeanddate.com
  3. ^ Time Zone in El Aaiún, Western Sahara Archived February 14, 2021, at the Wayback Machine, Timeanddate.com
  4. ^ a b Decree no. 2017-292 of 6 March 2017 relative to French legal time Archived December 2, 2020, at the Wayback Machine, Légifrance, 8 March 2017 (in French).
  5. ^ "Latitude and Longitude of World Cities". Infoplease. Archived from the original on May 24, 2011. Retrieved April 18, 2012.
  6. ^ "WESTMINSTER MEDICAL SOCIETY. Saturday, November 21, 1840". The Lancet. 35 (901): 383. December 1840. doi:10.1016/s0140-6736(00)59842-0. ISSN 0140-6736. Archived from the original on March 30, 2021. Retrieved January 27, 2021.
  7. ^ "Bristol Time". GreenwichMeanTime.com. Archived from the original on June 28, 2006. Retrieved December 5, 2011.
  8. ^ "Telegraph line laid across Cook Strait". New Zealand Ministry for Culture and Heritage. Archived from the original on February 18, 2020. Retrieved January 5, 2020.
  9. ^ "Our Time. How we got it. New Zealand's Method. A Lead to the World". Papers Past. Evening Post. p. 10. Archived from the original on October 8, 2013. Retrieved October 2, 2013.
  10. ^ Alfred, Randy (November 18, 2010). "Nov. 18, 1883: Railroad Time Goes Coast to Coast". Wired. Archived from the original on August 19, 2018. Retrieved July 30, 2018.
  11. ^ "Economics of Time Zones" (PDF). Archived from the original (PDF) on May 14, 2012.  (1.89 MB)
  12. ^ "The Times Reports on "the Day of Two Noons"". History Matters. Archived from the original on April 4, 2012. Retrieved December 5, 2011.
  13. ^ "Resolution concerning new standard time by Chicago". Sos.state.il.us. Archived from the original on October 5, 2011. Retrieved December 5, 2011.
  14. ^ Quirico Filopanti from scienzagiovane, Bologna University, Italy. Archived January 17, 2013, at the Wayback Machine
  15. ^ Gianluigi Parmeggiani (Osservatorio Astronomico di Bologna), The origin of time zones Archived August 24, 2007, at the Wayback Machine
  16. ^ Fleming, Sandford (1886). "Time-reckoning for the twentieth century". Annual Report of the Board of Regents of the Smithsonian Institution (1): 345–366. Reprinted in 1889: Time-reckoning for the twentieth century at the Internet Archive.
  17. ^ Stromberg, Joseph (November 18, 2011). "Sandford Fleming Sets the World's Clock". Smithsonian Magazine.
  18. ^ "Time Zone & Clock Changes in Kathmandu, Nepal". www.timeanddate.com. Archived from the original on January 22, 2021. Retrieved December 1, 2020.
  19. ^ Schiavenza, Matt (November 5, 2013). "China Only Has One Time Zone—and That's a Problem". The Atlantic. Archived from the original on August 22, 2018. Retrieved August 22, 2018.
  20. ^ "Russia Reduces Number of Time Zones". TimeAndDate.com. March 23, 2010. Archived from the original on August 9, 2020. Retrieved May 31, 2020.
  21. ^ "About Time: Huge country, nine time zones" (Video). BBC. March 22, 2011. Archived from the original on February 13, 2019. Retrieved February 12, 2019.
  22. ^ "Russian clocks to retreat again in winter, 11 time zones return". Reuters. July 2014. Archived from the original on October 28, 2020. Retrieved October 25, 2020.
  23. ^ "In Canada, You Can Just Write the Date Whichever Way You Want". Atlas Obscura. June 8, 2015. Archived from the original on August 22, 2018. Retrieved August 22, 2018.
  24. ^ a b "Z – Zulu Time Zone (Time Zone Abbreviation)". TimeAndDate.com. Archived from the original on August 22, 2018. Retrieved August 22, 2018.
  25. ^ "What is UTC or GMT Time?". www.nhc.noaa.gov. Archived from the original on August 22, 2018. Retrieved August 22, 2018.
  26. ^ Time Zone Abbreviations – Worldwide List Archived August 21, 2018, at the Wayback Machine, Timeanddate.com.
  27. ^ Bowditch, Nathaniel. American Practical Navigator. Washington: Government Printing Office, 1925, 1939, 1975.
  28. ^ Hill, John C., Thomas F. Utegaard, Gerard Riordan. Dutton's Navigation and Piloting. Annapolis: United States Naval Institute, 1958.
  29. ^ Howse, Derek. Greenwich Time and the Discovery of the Longitude. Oxford: Oxford University Press, 1980.ISBN 0-19-215948-8.
  30. ^ What Is Cruise Ship Time? Archived March 30, 2021, at the Wayback Machine, Cruise Critic, January 8, 2020.
  31. ^ Frequently Asked Questions Archived February 14, 2021, at the Wayback Machine, Caribbean Adventures Roatan.
  32. ^ Poulle, Yvonne (1999). "La France à l'heure allemande" (PDF). Bibliothèque de l'École des Chartes. 157 (2): 493–502. doi:10.3406/bec.1999.450989. Archived (PDF) from the original on September 4, 2015. Retrieved January 11, 2012.
  33. ^ "法定时与北京时间" (in Chinese). 人民教育出版社. Archived from the original on November 14, 2006.
  34. ^ Vigo, Galicia, Spain – Sunrise, Sunset, and Daylength Archived November 10, 2015, at the Wayback Machine, Timeanddate.com.
  35. ^ Stockholm, Sweden – Sunrise, Sunset, and Daylength Archived February 9, 2021, at the Wayback Machine, Timeanddate.com.
  36. ^ O'Hara, Doug (March 11, 2007). "Alaska: daylight stealing time". Far North Science. Archived from the original on September 27, 2007. Retrieved May 11, 2007.
  37. ^ Alaskan village to get two sunsets Friday Archived October 20, 2020, at the Wayback Machine, United Press International, August 7, 1986.
  38. ^ Kashgar, Xinjiang, China – Sunrise, Sunset, and Daylength Archived November 8, 2020, at the Wayback Machine, Timeanddate.com
  39. ^ "International CNN". Edition.cnn.com. Archived from the original on March 10, 2018. Retrieved December 5, 2011.
  40. ^ "United States CNN". Cnn.com. Archived from the original on September 11, 2001. Retrieved December 5, 2011.
  41. ^ "Guidelines for Ubuntu IRC Meetings". Canonical Ltd. August 6, 2008. Archived from the original on February 25, 2011. Retrieved July 13, 2009.
  42. ^ How time zone normalization works in Microsoft Outlook Archived October 6, 2015, at the Wayback Machine. Microsoft (2015).
  43. ^ Use Google Calendar in different time zones Archived October 16, 2015, at the Wayback Machine. Google Calendar Help (as of Oct. 2015)
  44. ^ "The Open Group Base Specifications Issue 7, section 4.16 Seconds Since the Epoch". The Open Group. Archived from the original on December 22, 2017. Retrieved January 22, 2017.
  45. ^ "tzset(3) man page from FreeBSD 12.1-RELEASE". freebsd.org. The FreeBSD project. Archived from the original on August 9, 2020. Retrieved April 21, 2020.
  46. ^ "GetSystemTime function (Windows)". msdn.microsoft.com. Archived from the original on February 13, 2018. Retrieved February 13, 2018.
  47. ^ "Timezone Updater Tool". Java.sun.com. Archived from the original on November 24, 2011. Retrieved December 5, 2011.
  48. ^ "Joda-Time". Joda-time.sourceforge.net. Archived from the original on December 3, 2011. Retrieved December 5, 2011.
  49. ^ "tz database". Twinsun.com. December 26, 2007. Archived from the original on June 23, 2012. Retrieved December 5, 2011.
  50. ^ "ECMAScript 2015 Internationalization API Specification". ecma-international.org. ECMA International. June 2015. Archived from the original on October 26, 2019. Retrieved September 4, 2019.
  51. ^ "Internationalization Support". Node.js v12.10.0 Documentation. Archived from the original on August 28, 2019. Retrieved September 4, 2019.
  52. ^ "DateTime". METACPAN. Archived from the original on March 29, 2014. Retrieved April 14, 2014.
  53. ^ "DateTime". Php.net. Archived from the original on November 22, 2011. Retrieved December 5, 2011.
  54. ^ "pytz module". Pytz.sourceforge.net. Archived from the original on November 30, 2011. Retrieved December 5, 2011.
  55. ^ "zoneinfo module". www.python.org. Archived from the original on February 7, 2021. Retrieved February 8, 2021.
  56. ^ Chronos Date/Time Library Archived April 5, 2014, at the Wayback Machine
  57. ^ "Ask the Crew: STS-111". National Aeronautics and Space Administration. June 19, 2002. Archived from the original on September 28, 2015. Retrieved September 10, 2015.
  58. ^ Lu, Ed (September 8, 2003). "Day in the Life". National Aeronautics and Space Administration. Archived from the original on September 1, 2012. Retrieved September 10, 2015.
  59. ^ New Tricks Could Help Mars Rover Team Live on Mars Time Archived August 12, 2014, at the Wayback Machine, Megan Gannon, Space.com, September 28, 2012.
  60. ^ "Map Maker Sun Clock". mapmaker.com. Retrieved July 9, 2022.

Further reading

External links

Media files used on this page

Flag of the United States.svg
Author/Creator: unknown, Licence: PD
Flag of Canada (Pantone).svg
Flag of Canada introduced in 1965, using Pantone colors. This design replaced the Canadian Red Ensign design.
Flag of Mexico.svg
Flag of Mexico Official version of the Flag of the United Mexican States or Mexico, adopted September 16th 1968 by Decree (Published August 17th 1968), Ratio 4:7. The previous version of the flag displayed a slightly different Coat of Arms. It was redesigned to be even more resplendent due to the upcoming Mexico City 1968 Olympic Games; According to Flag of Mexico, the colors are Green Pantone 3425 C and Red Pantone 186 C. According to [1] or [2], that translates to RGB 206, 17, 38 for the red, and RGB 0, 104, 71 for the green.
Flag of Ecuador.svg
Made by author of Xramp, first uploaded by Denelson83 as Flag of Ecuador.svg, modifications by Husunqu.
Flag of Chile.svg
It is easy to put a border around this flag image
Flag of Brazil.svg
Author/Creator: unknown, Licence: PD
Flag of Jamaica.svg
Flag of Jamaica. “The sunshine, the land is green, and the people are strong and bold” is the symbolism of the colours of the flag. GOLD represents the natural wealth and beauty of sunlight; GREEN represents hope and agricultural resources; BLACK represents the strength and creativity of the people. The original symbolism, however, was "Hardships there are, but the land is green, and the sun shineth", where BLACK represented the hardships being faced.
Flag of Haiti.svg
The national and official state flag of Haiti; arms obtained from http://www.webchantier.com/. The civil flag can be found at here.
Flag of Aruba.svg
The flag of Aruba
Flag of Curaçao.svg
The flag of Curaçao is a blue field with a horizontal yellow stripe slightly below the midline and two white, five-pointed stars in the canton. The geometry and colors are according to the description at Flags of the World.
Flag of the Dominican Republic.svg
The flag of the Dominican Republic has a centered white cross that extends to the edges. This emblem is similar to the flag design and shows a bible, a cross of gold and 6 Dominican flags. There are branches of olive and palm around the shield and above on the ribbon is the motto "Dios,Patria!, Libertad" ("God, Country, Freedom") and to amiable freedom. The blue is said to stand for liberty, red for the fire and blood of the independence struggle and the white cross symbolized that God has not forgotten his people. "Republica Dominicana". The Dominican flag was designed by Juan Pablo Duarte, father of the national Independence of Dominican Republic. The first dominican flag was sewn by a young lady named Concepción Bona, who lived across the street of El Baluarte, monument where the patriots gathered to fight for the independence, the night of February 27th, 1844. Concepción Bona was helped by her first cousin María de Jesús Pina.
Flag of Portugal.svg
Flag of Portugal, created by Columbano Bordalo Pinheiro (1857-1929), officially adopted by Portuguese government in June 30th 1911 (in use since about November 1910). Color shades matching the RGB values officially reccomended here. (PMS values should be used for direct ink or textile; CMYK for 4-color offset printing on paper; this is an image for screen display, RGB should be used.)
Flag of Iceland.svg
The Flag of Iceland.
  • Horizontal aspect ratio: 7:1:2:1:14;
  • Vertical aspect ratio: 7:1:2:1:7.
Flag of Côte d'Ivoire.svg
Flag of the Ivory Coast, written by Jon Harald Søby, modified by Zscout370. The colors match to what is reported at http://fotw.vexillum.com/flags/ci.html.
Flag of Mauritania.svg
Flag of Mauritania, adopted in 2017. The National Assembly added red stripes to the top and bottom edges to represent “the blood shed by the martyrs of independence”.
Flag of the United Kingdom.svg
Flag of the United Kingdom, Union Jack or Union Flag in a 1:2 ratio (typical on British warships and also the rank flag of an admiral of the fleet).
Flag of Senegal.svg
Flag of Senegal
Flag of Sao Tome and Principe.svg
Flag of São Tomé and Príncipe
Flag of Ireland.svg
Note that the green portion of the flag was designed to represent the majority Catholic residents of the island, the orange side the minority Protestant and the white middle part peace and harmony between them.
Flag of Spain.svg
Author/Creator: unknown, Licence: PD
Flag of the Central African Republic.svg
The proportions of this flag are 3:2; however, there is no official definition for the correct proportions and also 5:3 is widely used.
Flag of the Democratic Republic of the Congo.svg
The national flag of the Democratic Republic of the Congo. Created according to the 2006 constitution : Son emblème est le drapeau bleu ciel, orné d’une étoile jaune dans le coin supérieur gauche et traversé en biais d’une bande rouge finement encadrée de jaune. (Its symbol is a sky blue flag, decorated with a yellow star in the upper left corner and crossed in the diagonal by a red strip with thin yellow borders) It seems to be identical, except for a lighter field hue, to the 1966–1971 flag.
Flag of Niger.svg
This flag was created with a text editor.
Flag of Albania.svg
Flag of Albania
Flag of Austria.svg
Flag of Austria with the red in the Austrian national colours which was official ordered within the Austrian Armed Forces (Bundesheer) in the characteristic “Pantone 032 C” (since May 2018 the Red is ordered in the characteristic “Pantone 186 C”.)
Flag of Belgium (civil).svg
The civil ensign and flag of Belgium. It is identical to Image:Flag of Belgium.svg except that it has a 2:3 ratio, instead of 13:15.
Flag of Croatia.svg
It is easy to put a border around this flag image
Flag of Germany.svg
Author/Creator: unknown, Licence: PD
Flag of Italy.svg
Author/Creator: unknown, Licence: PD
Flag of Liechtenstein.svg
Flag of Liechtenstein
Flag of Montenegro.svg
Flag of the Republic of Montenegro (adopted on 13 July 2004) - RGB colours, official 1:2 dimensions and construction details based partly on the templates: Flag (Government of Montenegro) and Coat of arms (Government of Montenegro).
Flag of Norway.svg
Flag of Norway. The colors approximately correspond to Pantone 200 C (deep red) and 281 C (dark blue).
Flag of Slovenia.svg
The flag of Slovenia.
"The construction sheet for the coat of arms and flag of the Republic of Slovenia
is issued in the Official Gazette Uradni list Republike Slovenije #67, 27 October 1994
as the addendum to the Law on the coat of arms and flag."
Flag of Sweden.svg
Author/Creator: unknown, Licence: PD
Flag of the Vatican City.svg
Author/Creator: Unknown authorUnknown author, Licence: CC0
Flag of the Vatican City.
Flag of Namibia.svg
Flag of Namibia
Flag of Rwanda.svg
Flag of Rwanda. The flag ratio is 2:3 with the stripes being 2:1:1. Colors are the following officially: Pantone 299 C 2X (blue), RAL 6029 (green), RAL 1023 (yellow) and RAL 1003 (golden yellow). (As of 03/08/2010, the only color used is the Pantone 299 C, which is from here. The rest of the colors are RAL shades from here.)
Flag of Estonia.svg
Flag of Estonia 7:11, blue PANTONE 285C.
Flag of Greece.svg
Flag of Greece (since 1978) and Naval Ensign of Greece (since 1828)
Flag of Israel.svg
Flag of Israel. Shows a Magen David (“Shield of David”) between two stripes. The Shield of David is a traditional Jewish symbol. The stripes symbolize a Jewish prayer shawl (tallit).
Flag of Syria.svg
It is easy to put a border around this flag image
Flag of Ethiopia.svg
Flag of Ethiopia
Flag of Iran.svg
Flag of Iran. The tricolor flag was introduced in 1906, but after the Islamic Revolution of 1979 the Arabic words 'Allahu akbar' ('God is great'), written in the Kufic script of the Qur'an and repeated 22 times, were added to the red and green strips where they border the white central strip and in the middle is the emblem of Iran (which is a stylized Persian alphabet of the Arabic word Allah ("God")).
The official ISIRI standard (translation at FotW) gives two slightly different methods of construction for the flag: a compass-and-straightedge construction used for File:Flag of Iran (official).svg, and a "simplified" construction sheet with rational numbers used for this file.
Flag of Australia (converted).svg

Flag of Australia, when congruence with this colour chart is required (i.e. when a "less bright" version is needed).

See Flag of Australia.svg for main file information.
Flag of Maldives.svg
Flag of Maldives. The colours used are Pantone 186 C for red and Pantone 348 C for green.
Flag of India.svg
Author/Creator: unknown, Licence:
Flag of Laos.svg
Flag of Laos
Flag of Thailand.svg
The national flag of Kingdom of Thailand since September 2017; there are total of 3 colours:
  • Red represents the blood spilt to protect Thailand’s independence and often more simply described as representing the nation.
  • White represents the religion of Buddhism, the predominant religion of the nation
  • Blue represents the monarchy of the nation, which is recognised as the centre of Thai hearts.
Flag of Malaysia.svg
Flag of Malaysia – Jalur Gemilang (Stripes of Glory)
Flag of Japan.svg
Author/Creator: unknown, Licence: PD
Flag of Guam.svg
The flag of Guam, courtesy an e-mail from the author of xrmap. Modifications by Denelson83.
Flag of Papua New Guinea.svg
Flag of Papua New Guinea
Colours: Pantone 186 C for red and 116 C for yellow
Flag of Fiji.svg
Author/Creator: unknown, Licence: CC0
Flag of New Zealand.svg
Flag of New Zealand. Specification: http://www.mch.govt.nz/nzflag/description.html , quoting New Zealand Gazette, 27 June 1902.
Flag of Tonga.svg
Author/Creator: unknown, Licence: CC0
The Earth seen from Apollo 17.jpg
"The Blue Marble" is a famous photograph of the Earth taken on December 7, 1972, by the crew of the Apollo 17 spacecraft en route to the Moon at a distance of about 29,000 kilometres (18,000 mi). It shows Africa, Antarctica, and the Arabian Peninsula.
World Time Zone Chart 1942.jpg
Time Zone Chart of the World. Originally published 1928, New Edition 1942. Reproduced in: Admiralty Navigation Manual Vol 1 (1938)
DaylightSaving-World-Subdivisions.png
Author/Creator: Paul Eggert, Licence: CC-BY-SA-3.0
World map showing current and past daylight saving time usage. The Spring-forward/Fall-back adjustment is a common practice at high latitudes.
  DST is used.
  DST is no longer used.
  DST has never been used.
Flag of the Turks and Caicos Islands.svg
Flag of the Turks and Caicos Islands
Aleutian Islands with 180th meridian and International Date Line (cropped).png
Author/Creator: First file version uploader was User:Jailbird, Licence: CC-BY-SA-3.0
Map illustrating the current (post 2011) International Date Line
Solar time vs standard time.png
It's a Solar Time Vs Standard Time Map of Timezones in the World.
Flag of the Cocos (Keeling) Islands.svg
Flago de la Kokosinsuloj, uzo ne oficiala
Flag of Nauru.svg
The national flag of Nauru. Official Pantone colours are: PMS 280 blue, PMS 123 yellow.
Flag of Tuvalu.svg
Author/Creator: Nightstallion (original)
Zscout370 (most recent), Licence: CC0
Flag of Tuvalu.

FIAV 111111.svg
World time zones.svg
Author/Creator: Heitordp, Licence: CC0
Time zones of the world
Flag of the Northern Mariana Islands.svg
Author/Creator: unknown, Licence: CC0
Flag of Dominica.svg
Author/Creator: See File history below for details., Licence: CC0
The Flag of Dominica.
Flag of the Isle of Man.svg
Author/Creator: Edited by Reisio, Alkari, e.a., Licence: CC0
Flag of the Isle of Man
Time zone map of the United States 1913 (colorized).png
Colorized version of File:Time zone map of the United States 1913.tif, showing old time zones of the USA from the year 1913. The colors used are chosen from the conventions of WikiProject Maps on the English Wikipedia.
Flag of Anguilla.svg
Flag of Anguilla (adopted on 30 May 1990) - RGB colours, 1:2 dimensions and construction details based partly on the templates: Flag of Anguilla – A Brief History
Flag of South Ossetia.svg
Flag of South Ossetia
Flag of the Pitcairn Islands.svg
The flag of the Pitcairn Islands, arms courtesy an e-mail from the author of xrmap and the Blue Ensign from Image:Government Ensign of the United Kingdom.svg
Wooden hourglass 3.jpg
Author/Creator: User:S Sepp, Licence: CC-BY-SA-3.0
Alternative version of image:Wooden hourglass 2.jpg. Wooden hourglass. Total height:25 cm. Wooden disk diameter: 11.5 cm. Running time of the hourglass: 1 hour. Hourglass in other languages: 'timglas' (Swedishrtrttttyo), 'sanduhr' (German), 'sablier' (French), 'reloj de arena' (Spanish), 'zandloper' (Dutch), 'klepsydra' (Polish), 'přesýpací hodiny' (Czech), 'ampulheta' (Portuguese).
Flag of Gibraltar.svg
Flag of Gibraltar
Tzdiff-Europe-summer.png
Author/Creator: Naive cynic at English Wikipedia, Licence: CC-BY-SA-3.0
Difference between legal time and local mean time in Europe during the summer.
Time zone chicago.jpg
Author/Creator: JoeSmack, Licence: CC BY-SA 3.0
Chicago, IL - USA. Taken while on vacation visiting my brother in the windy city.
Flag of Transnistria (state).svg
Flag of the Pridnestrovian Moldavian Republic (Pridnestrovie, Transdniestria, Transnistria). The flag's reverse omits the hammer and sickle
World Time Zones Map.png
Map of current official time zones.
Marine sandglass MMM.jpg
© Marie-Lan Nguyen / Wikimedia Commons, CC BY 2.5
Marine sandglass.
Flags of New Caledonia.svg
Drapeaux de la France et de la Nouvelle-Calédonie côte-à-côte.
Coventry Time Zone Clock.jpg
Author/Creator: Cmglee, Licence: CC BY-SA 3.0
Time Zone Clock control panel in front of Coventry Transport Museum.
Flag of Norfolk Island.svg
Author/Creator: unknown, Licence: CC0