The prime meridian refers to the zero degree longitude on the earth. The longitude indicates the north-south direction. All longitude lines are equal in length. The degrees marked on the longitude lines are longitude.The longitude that passes through the original site of Greenwich Observatory in London, England, is called 0 ° longitude, also called prime meridian.[1]
Chinese name
Prime meridian
Foreign name
prime meridian；time meridian
Alias
0 ° longitude、First meridian、Zero meridian
fix hour
October 13, 1884
Specific address
Former site of the Royal Greenwich Observatory, London, UK
Because it was not like the starting point of latitude (i.eequator）Can be set byEarth rotation axisIt was decided that theoretically any meridian can be defined as the prime meridian, so there were different positions of this meridian in history.1851 Imperial AstronomerSir George AirySet at Greenwich ObservatoryTransitAnd thus determine the Greenwich meridian.Because more than two-thirds of the ships at that time had already used this line as the reference meridianWashington DCHeldInternational Meridian ConferenceIt is officially defined as the starting point of longitude.A total of 41 representatives from 25 countries participated in the meeting. The French representative abstained from voting. Before 1911, France was stillParis MeridianAs the starting point of longitude.
Starting from the Arctic, the prime meridian passes through Britain, France, SpainAlgeria、Mali、burkina faso , Togo andGhanaA total of 8 countries, then to the South Pole.
In addition to defining longitude,Greenwich meridianIt was also used as a time standard.In theory,Greene treatmentQuasi timeThe noon of is the time when the sun crosses the Greenwich meridian.But becauseEarth rotation speedIrregular, standard time has been changed fromCoordinated Universal Timereplace.
Geographic definition
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Primary Meridian at Greenwich Observatory
The starting longitude for measuring longitude on the earth.Also called zero meridian.From the prime meridian, measure the geographic longitude from 0 ° to 180 ° eastward and westward respectively.The International Meridian Conference held in Washington in 1884 decided to use the meridian of the Eli transit at the Royal Observatory (former site) in Greenwich (Greenwich), London, England, as the standard reference meridian for time and longitude measurement, called the prime meridian.After 1957greenwich observatory Migration station address,International Time BureauUsing several observatories in theequatorThe longitude origin of the average observatory is defined on theChronometryData is calculated.Passed since 1968International customary originAnd the meridian of the longitude origin of the average observatory as the primary meridian.The longitude zero point of the earth coordinate system determined by various new technologies is consistent with the primary meridian as far as possible, but there is often less than 1 "zero difference.
The prime meridian is the zero degree longitude on the earth. It is the standard reference meridian used to determine the earth's longitude and global timeWeftThere is a natural starting point - the equator.
Before the 19th century, many countries adoptedCanary IslandsYaro IslandThe meridian of.That meridian is equivalent to today'sWestern Meridian17 ° 39 ′ 46 ″ meridian.In the first half of the 19th century, many countries took the meridian passing through their main observatories as the primary meridian.In this way, there are several primary meridians in the world at the same timeGeodesyIt has brought a lot of inconvenience.So on October 13, 1884, the International Conference of Astronomers' Representatives held in Washington decided to take the longitude passing through Greenwich, southeast of London, England, as the prime meridian, as the starting point of computing geography and the world standard "time zone".Later, it was designated as InternationalStandard timeEvery other day.
Longitude values are measured from the original meridian to the east and west, respectively 0 ° - 180 ° or 0-12 hours.The east of the prime meridian is the east longitude, and the west is the east longitudeWestern Meridian, the global longitude measurement is based on the primary meridian andequatorThe intersection point E of is the origin of longitude.After 1957,greenwich observatory For the relocation of the observatory site, several observatories with good long-term stability are used internationally to maintain the longitude origin, and the original longitude values of these observatories are used to reverse the longitude origin.Then, the point as the global longitude origin is determined and maintained by the difference between the average value of the longitude origin and the E point.
The world famous Greenwich Observatory was built in 1675.At that time, the British navigation industry developed rapidly.In order to solve the need to measure longitude at sea, the British authorities decided to establish an observatory in the Royal Greenwich Garden on the Thames River, about 20 kilometers southeast of London from the city center.After 1835, the Greenwich Observatory was expanded and updated under the leadership of the outstanding astronomer Eric.He pioneered the use of the "meridian circle" to measure GreenwichFlat solar time。The observatory became the world's most advanced time measuring observatory at that time.With the development of world navigation, many countries have established observatories to measureLocal time。
In order to coordinate the measurement and determination of time internationallyGeographic longitudeIn 1884, the International Longitude Conference was held in Washington.The meeting decided to adoptgreenwich observatory The longitude where the Erie transit is located, as the standard reference longitude for global time and longitude measurement, is called 0 ° longitude or prime meridian.Since then, maps published by various countries not only use this line as the starting point of geographical longitude, but also use the Greenwich Observatory as the starting point“World Time Zone”The starting point of, use Greenwich chronograph to calibrate time.
Change of address
City of LondonHas developed into a world famousIndustrial city。After the war, the population in Greenwich increased dramatically, the number of factories increased, and the air pollution became more and more serious, especially the interference of night lights, which was extremely detrimental to star observation.This forced the observatory to move to Sussex on the southeast coast of England in 1948Hearst Montsoulberg。The environment here is beautiful, the air is fresh, and the observation conditions are good.The observatory moved to the new site is still called the Royal Greenwich Observatory.However, the Greenwich Observatory is not on the 0 ° longitude line, and the 0 ° longitude line on the earth still passes through the former site of the Greenwich Observatory.
Chronicle of Events
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The First International Geography Conference
The first session in 1871International Geographical ConferencestayBelgiumAntwerpAt the meeting, a resolution was made: "The charts of all countries should be adopted uniformlyGreenwich meridianIs zeroMeridianAnd put it into practice within 15 years. "
The 7th International Geodetic Conference
The 7th International Geodetic Conference was held in Rome in October 1883,Meeting resolution"The prime meridian must pass through the primary observatory. Considering the fact that 90% of the sailors engaged in overseas trade have taken the Greenwich meridian as the benchmark to calculate the position (longitude) of the ship, governments should use the Greenwich meridian as the prime meridian." On the time issue,The meeting held that it would be very convenient to adopt a unified world in international exchanges.
International Meridian Conference
On October 1, 1884, the International Meridian ConferenceWashington, USAConvening.Finally, the General Assembly adopted seven resolutions, three of which:
Resolution II: Governments attending the Conference should adoptgreenwich observatory The meridian at the center of the meridian circle is the prime meridian.
Resolution 5: World Day starts from zero o'clock on the original meridian, and the Civil Day also starts fromMidnightStart at zero.
So far, the beginningmeridian, Universal Time, etc. were finally established and recognized by most countries.[3]
Origin of name
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Chinese name: Prime Meridian
English name: prime meridian
0 ° longitude, is the starting point for calculating east-west longitude.In 1884, the international conference decided to adopt the BritishGreenwich(Greenwich) original site of the observatoryMeridian instrumentThe meridian in the center is the prime meridian.After 1957, the Greenwich Observatory moved its site.In 1968Origin of international agreements(CIO: Conventional international origin)GeopoleThe origin and longitude origin are actually unchanged.
PrimitivemeridianAlso known as "first meridian" or "zero meridian", the formulation and use of the original meridian have changed.
Source of name: The ancients took "Zi" as the north and "Wu" as the south (such as the Imperial Palacethe Meridian GateTherefore, the longitude in geography is also called the meridian in China, and the zero degree longitude is the prime meridian.
effect
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greenwich observatory The former site later became the British Department of Navigation and the National Marine Museum Astronomical Station.It displays the early astronomical instruments, especially the copper wires embedded on the ground in the Meridian Hall——0 ° longitude, attracting visitors from all over the world.Tourists here like to take photos with their feet on both sides of the 0 ° longitude, which symbolizes that they are standing on both east longitude and west longitude.
After the Royal Observatory moved to a new site in 1950, it was incorporatedNational Marine MuseumThere are astronomical stations, astronomical instrument halls, etc., which are mainly used for exhibition.Among the historical astronomical materials on display are early astronomical telescopes, clocks designed in early times in various countriesglobe、Armillary sphere(Many of them were made in China at that time, and many astronomical phenomena were discovered (such as Halley's Comet)).
