Global 24 time Zones Division
The World Time Zone table, which can display time and place names in each of the world's time zones, is more sophisticated and complex than the two-way timetable, and usually the world time zone table's dial will mark the city names of the 24 time zones worldwide, but exactly how these 24 time zones are generated. In the past, local time has been set up in different parts of the world, but with the development of transportation and telecommunications, frequent exchanges and local time, which has caused many problems, so when the International conference in 1884 set a global standard, Stipulate to the beginning of the Zero meridian (also known as the Prime Meridian) in Greenwich, London, and to rotate the Earth from west to east every 24 hours 360°, to set a longitude of 15°, time difference of 1 hours. The longitude of each 15 ° is called the central meridian of the time zone, which divides the world into 24 time zones, which contain 23 full time zones and 2 half-time zones on the left and right sides of the 180° warp. In the global time, east longitude is earlier than West longitude, that is, if GMT is 12 o'clock noon, then the central Meridian 15°e time zone is 1 o'clock in the afternoon, central Meridian 30°e timezone is 2 o'clock in the afternoon; Conversely, the time zone of the central Meridian 15°w is 11 o'clock in the morning and the central meridian 30° The time in the W time zone is 10 o'clock in the morning. Taiwan, for example, is located at 121 ° Longitude and has a 8-hour time difference with Greenwich after conversion. If the two people at the same time from the 0° of Greenwich East, west, when they are in the longitude of 180°, it will be 24 hours apart, so the warp 180° is designated as the International Day Line, from west to east through this line date to subtract one, conversely, if from east to west to increase one day.
Greenwich Mean Time GMT
In 17th century, the Royal Observatory of Greenwich was observing astronomical objects for the expansion of its naval hegemony. The Old Royal Observatory (Observatory) was formally established in 1675, and by 1884 it was decided to use the meridian of Greenwich to divide the Earth's two hemispheres by longitude 0 degrees. There is a sign on the wall of the observatory 24 Hour clock, showing the current time, for the world, the time set here is the world time reference point, the whole world in Greenwich time as standard to set the time, this is our familiar "Greenwich Standard Time" (Greenwich Mean Times , referred to as g.m.t.) The origin, marked on the watch, means that the table has two time functions, that is, the time of the home and another country can be displayed.
World Coordination Time UTC
Most of the two places have a timetable of GMT, but some of the two places do not see GMT on the timetable, but instead, the 3 English letters in UTC are UTC. In fact, UTC refers to the coordinated Universal time-World coordination Time (also known as World standard Time, world unification Time), which is the new time scale after the average solar time (GMT), the axis movement is revised, and the " Seconds "is the time when the international atom of the Unit is synthesized, and the computational process is rigorous and precise, so UTC is more accurate than GMT in terms of" world standard Time ". Its error value must be kept within 0.9 seconds, if greater than 0.9 seconds by the International Earth Rotation Transaction Central Bureau in Paris to release a leap second, so that UTC and the Earth's rotation period is consistent. So basically the nature of UTC emphasizes the world time standard, which is more precise than GMT, but there is no difference between the function and accuracy of GMT and UTC for current models.
Summer Time saving DST
The so-called "summer Saving Time"daylight Saving "(abbreviated as D.S.T), refers to the summer sun rises earlier, the clock is set to one hour faster to use early daylight, in the UK is known as Daylight savings Time (Summer time). The idea was presented by the American Benjamin Franklin in 1784, and in 1915 Germany became the first country to formally implement daylight saving time to reduce lighting and power consumption. Since then, the practice has been cited by some 70 countries around the world, mainly in Europe and North America. India, now divided into two time zones, is also discussing whether the country should implement daylight saving time in a unified way. European mobile phones also have a lot of GSM system base station, in addition to the delivery of local time also includes daylight saving time, as the time standard for mobile phones, users can decide to turn on or off. It is worth noting that some countries have the implementation of "Summer saving Time" system, do not forget to go abroad to follow the local habit of adjusting on the table, which is not the mechanical watch functional design OH.
CST can also represent the following 4 different time zones:
Central Standard Time (USA) ut-6:00
Central Standard Time (Australia) ut+9:30
China Standard Time ut+8:00
Cuba Standard Time ut-4:00
It can be seen that CST could also represent the standard time in four countries of the United States, Australia, China, and Cuba.