World Time Zone Map
Current Greenwich World Time
The Geochron Global Time Indicator simultaneously shows the correct time, day, date, and distribution of daylight and darkness everywhere on the Earth...at a glance. NASA, the CIA, the United States Treasury Department, the Air Force, the Navy, and the Coast Guard use the Geochron to provide simultaneous global information. Whether you are a president, potentate, business executive, student, or world traveler, Geochron is the perfect device for your global time orientation needs.
Geochron includes a 0 to 60-minute analog scale, which is located at the top of the map and is set in five-minute increments. The map itself is a continuous belt of mylar film in constant motion, moving from left to right one inch per hour in synchronization with the Earth`s orbit around the Sun. Precision indicators display the month, day, and time for all 40 time zones. Geochron also displays the winter solstice, summer solstice, and fall and spring equinoxes each year as well as the current seasons everywhere in the world.
Geochron includes a 0 to 60-minute analog scale, which is located at the top of the map and is set in five-minute increments. The map itself is a continuous belt of mylar film in constant motion, moving from left to right one inch per hour in synchronization with the Earth`s orbit around the Sun. Precision indicators display the month, day, and time for all 40 time zones. Geochron also displays the winter solstice, summer solstice, and fall and spring equinoxes each year as well as the current seasons everywhere in the world.
Above is a World time zone map showing the standard time zones running east and west from Greenwich England. The above map is centered on Greenwich. The time given is for Greenwich World time.
Time Zones
Before 1972, all time zones were specified as an offset from Greenwich Mean Time (GMT), which was the mean solar time at the meridian passing through the Royal Observatory in Greenwich in London. Since 1972 all official time services have broadcast radio time signals synchronized to UTC, a form of atomic time that includes leap seconds to keep it within 0.9 seconds of this former GMT, now called UT1. Many countries now legally define their standard time relative to UTC, although some still legally refer to GMT, including the United Kingdom itself. UTC, also called Zulu time, is used everywhere on Earth by astronomers and others who need to state the time of an event unambiguously.
Time zones are based on Greenwich Mean Time (GMT), the mean solar time at longitude 0° (the Prime Meridian). The definition of GMT was recently changed – it was previously the same as UT1, a mean solar time calculated directly from the rotation of the Earth. As the rate of rotation of the Earth is not constant, the time derived from atomic clocks was adjusted to closely match UT1. In January 1972, however, the length of the second in both Greenwich Mean Time and atomic time was equalized. The readings of participating atomic clocks are averaged out to give a uniform time scale.
Because the length of the average day is a small fraction of a second more than 24 hours (slightly more than 86400 seconds), leap seconds are periodically inserted into Greenwich Mean Time to make it approximate to UT1. This new time system is also called Coordinated Universal Time (UTC). Leap seconds are inserted to keep UTC within 0.9 seconds of UT1. Because the Earth's rotation is gradually slowing, leap seconds will need to be added more frequently in future. However, from one year to the next the rotation rate is slightly irregular, so leap seconds are not added unless observations of Earth's rotation show that one is required. In this way, local times will continue to stay close to mean solar time and the effects of variations in Earth's rotation rate will be confined to simple step changes relative to the uniform time scale (International Atomic Time or TAI). All local times differ from TAI by an integral number of seconds. With the implementation of UTC, nations began to use it in the definition of their time zones. As of 2005, most nations had altered the definition of local time in this way.
In the United Kingdom, this involved redefining Greenwich Mean Time to make it the same as UTC. British Summer Time (BST) is still one hour in advance of Greenwich Mean Time and is therefore also one hour in advance of Coordinated Universal Time. Thus Greenwich Mean Time is the local time at the Royal Observatory, Greenwich between 0100 hours GMT on the last Sunday in October and 0100 hours GMT on the last Sunday in March. Similar circumstances apply in many other places.
Looking to the future, leap seconds are considered by many to be a nuisance, and ways to abolish them are being considered. This means letting the time difference accumulate. One suggestion is to insert a "leap-hour" in about 5,000 years. For more on this discussion read Proposal to abolish leap seconds.
Notation of time
ISO 8601
Main article: ISO 8601
UTC
If the time is in Coordinated Universal Time (UTC), add a "Z" directly after the time without a space. "Z" is the zone designator for the zero UTC offset. "09:30 UTC" is therefore represented as "09:30Z" or "0930Z". "14:45:15 UTC" would be "14:45:15Z" or "144515Z".
UTC time is also known as "Zulu" time, since "Zulu" is the ICAO spelling alphabet code word for "Z".
Offsets from UTC
Offsets from UTC are written in the format ±[hh]:[mm], ±[hh][mm], or ±[hh]. So if the time being described is one hour ahead of UTC (such as the time in Berlin during the winter), the zone designator would be "+01:00", "+0100", or simply "+01". This is appended to the time in the same way that 'Z' was above. 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, would be "−06:00" for the winter (Central Standard Time) and "−05:00" for the summer (Central Daylight Time).
Abbreviations
Time zones(see below) are often represented by abbreviations such as "EST, WST, CST" but these are not part of the international time and date standard ISO 8601 and their use as sole designator for a time zone is not recommended. Such designations can be ambiguous. For example, "BST", which is British Summer Time, was renamed "British Standard Time" between 1968 and 1971 when Central European Time was in force because legislators objected to calling it Central European Time. The same legislation affirmed that the Standard Time within the United Kingdom was, and would continue to be, Greenwich Mean Time.
Time Zone Abbreviations:
Time in
USA and Canada
Atlantic Time (AST) (Canada), Eastern Time (EST), Central Time (CST), Mountain Time (MT), Pacific Time (PST), Alaska Time (AKST), Hawaii Time (HST), Daylight Saving Time (DST)
Europe:
Central European Time (CET), Eastern European Time (EET), Western European Time (WET), British Summer Time (BST)
Asia and Pacific Regions:
China Time (CST) | India Time (IST) | Japan Time (JST)
Countries on GMT:
Europe (Winter only)
United Kingdom, Ireland, Portugal
Africa:
Burkina Faso, Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Mauritania, Morocco, Sao Tome, Senegal, St Helena, Togo, Western Sahara
Time Zones
Before 1972, all time zones were specified as an offset from Greenwich Mean Time (GMT), which was the mean solar time at the meridian passing through the Royal Observatory in Greenwich in London. Since 1972 all official time services have broadcast radio time signals synchronized to UTC, a form of atomic time that includes leap seconds to keep it within 0.9 seconds of this former GMT, now called UT1. Many countries now legally define their standard time relative to UTC, although some still legally refer to GMT, including the United Kingdom itself. UTC, also called Zulu time, is used everywhere on Earth by astronomers and others who need to state the time of an event unambiguously.
Time zones are based on Greenwich Mean Time (GMT), the mean solar time at longitude 0° (the Prime Meridian). The definition of GMT was recently changed – it was previously the same as UT1, a mean solar time calculated directly from the rotation of the Earth. As the rate of rotation of the Earth is not constant, the time derived from atomic clocks was adjusted to closely match UT1. In January 1972, however, the length of the second in both Greenwich Mean Time and atomic time was equalized. The readings of participating atomic clocks are averaged out to give a uniform time scale.
Because the length of the average day is a small fraction of a second more than 24 hours (slightly more than 86400 seconds), leap seconds are periodically inserted into Greenwich Mean Time to make it approximate to UT1. This new time system is also called Coordinated Universal Time (UTC). Leap seconds are inserted to keep UTC within 0.9 seconds of UT1. Because the Earth's rotation is gradually slowing, leap seconds will need to be added more frequently in future. However, from one year to the next the rotation rate is slightly irregular, so leap seconds are not added unless observations of Earth's rotation show that one is required. In this way, local times will continue to stay close to mean solar time and the effects of variations in Earth's rotation rate will be confined to simple step changes relative to the uniform time scale (International Atomic Time or TAI). All local times differ from TAI by an integral number of seconds. With the implementation of UTC, nations began to use it in the definition of their time zones. As of 2005, most nations had altered the definition of local time in this way.
In the United Kingdom, this involved redefining Greenwich Mean Time to make it the same as UTC. British Summer Time (BST) is still one hour in advance of Greenwich Mean Time and is therefore also one hour in advance of Coordinated Universal Time. Thus Greenwich Mean Time is the local time at the Royal Observatory, Greenwich between 0100 hours GMT on the last Sunday in October and 0100 hours GMT on the last Sunday in March. Similar circumstances apply in many other places.
Looking to the future, leap seconds are considered by many to be a nuisance, and ways to abolish them are being considered. This means letting the time difference accumulate. One suggestion is to insert a "leap-hour" in about 5,000 years. For more on this discussion read Proposal to abolish leap seconds.
Notation of time
ISO 8601
Main article: ISO 8601
UTC
If the time is in Coordinated Universal Time (UTC), add a "Z" directly after the time without a space. "Z" is the zone designator for the zero UTC offset. "09:30 UTC" is therefore represented as "09:30Z" or "0930Z". "14:45:15 UTC" would be "14:45:15Z" or "144515Z".
UTC time is also known as "Zulu" time, since "Zulu" is the ICAO spelling alphabet code word for "Z".
Offsets from UTC
Offsets from UTC are written in the format ±[hh]:[mm], ±[hh][mm], or ±[hh]. So if the time being described is one hour ahead of UTC (such as the time in Berlin during the winter), the zone designator would be "+01:00", "+0100", or simply "+01". This is appended to the time in the same way that 'Z' was above. 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, would be "−06:00" for the winter (Central Standard Time) and "−05:00" for the summer (Central Daylight Time).
Abbreviations
Time zones(see below) are often represented by abbreviations such as "EST, WST, CST" but these are not part of the international time and date standard ISO 8601 and their use as sole designator for a time zone is not recommended. Such designations can be ambiguous. For example, "BST", which is British Summer Time, was renamed "British Standard Time" between 1968 and 1971 when Central European Time was in force because legislators objected to calling it Central European Time. The same legislation affirmed that the Standard Time within the United Kingdom was, and would continue to be, Greenwich Mean Time.
Time Zone Abbreviations:
Time in
USA and Canada
Atlantic Time (AST) (Canada), Eastern Time (EST), Central Time (CST), Mountain Time (MT), Pacific Time (PST), Alaska Time (AKST), Hawaii Time (HST), Daylight Saving Time (DST)
Europe:
Central European Time (CET), Eastern European Time (EET), Western European Time (WET), British Summer Time (BST)
Asia and Pacific Regions:
China Time (CST) | India Time (IST) | Japan Time (JST)
Countries on GMT:
Europe (Winter only)
United Kingdom, Ireland, Portugal
Africa:
Burkina Faso, Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Mauritania, Morocco, Sao Tome, Senegal, St Helena, Togo, Western Sahara