What is the background of the prime meridian

The prime meridian, also known as the "first meridian" or "zero meridian", is the starting meridian on the earth to calculate longitude. The formulation and use of the prime meridian is subject to change.

The prime meridian is the zero degree longitude on the earth, it is the standard reference meridian used to determine the longitude of the earth and the global time, it does not have a natural origin like the latitude.

Prior to the 19th century, many countries adopted the meridian route through Hierro Island, a Canary Islands in the Atlantic Ocean. That meridian corresponds to today's 17°39 46 west longitude. In the first half of the 19th century, many countries used the meridian passing through their main observatories as the prime meridian.

As a result, there were several prime meridians in the world at the same time, which brought many inconveniences to later navigation and geodetic surveys. Therefore, on October 13, 1884, the International Conference of Astronomers held in Washington, D.C., decided to use the meridian passing through Greenwich, southeast of London, England, as the prime meridian as the starting point for calculating geography and the world's standard "time zone". Later, this day was designated as International Standard Time Day.

The longitude value starts from the prime meridian and is measured to the east and west, respectively, at 0°-180° or 0-12° respectively. The east of the prime meridian is east longitude and the west is west longitude, and the global longitude measurement is based on the intersection point e of the prime meridian and the equator as the longitude origin. After 1957, the Greenwich Observatory moved to the site of the observatory, and several observatories with good long-term stability were used internationally to maintain the longitude origin, and the original longitude of these observatories was used to reverse the longitude origin of their respective longitude.

The point that is the origin of the global longitude is determined and maintained by the difference between the mean of these longitude origins and the difference between point e.

In 1968, the origin of the International Agreement (CIO) was used as the origin of the Earth's poles, and the meridian passing through the origin of the International Agreement and the origin of the longitude of the average observatory was called the "prime meridian". The longitude zeros of the earth coordinate system determined by various new technologies are as consistent as possible with the prime meridian, but there is often a zero difference of less than 1.

The meridian that passes through the former Greenwich Observatory is 0 degrees longitude, which is the prime meridian.

The prime meridian is also called the 0° meridian, the first meridian, and the zero meridian. On a globe, the line connecting the north and south poles is called the meridian or meridian. The meridian indicates the north-south direction, all the meridians are equal in length, and the degree marked by the meridian is the longitude.

Internationally, the meridian that passes through the original site of the Greenwich Observatory in London, England is called the 0° meridian, also known as the prime meridian.

The Greenwich Prime Meridian was determined on October 13, 1884, at the site of the Royal Observatory Greenwich, London, England.

Categories: Science & Engineering.

Analysis: The prime meridian, also known as the zero degree meridian, is a standard reference meridian established to determine the measurement of geographic longitude and coordination time. The earth has a natural zero-degree latitude - the equator, but there is no natural zero-degree longitude, so the prime meridian can only be artificially selected from an infinite number of meridians.

The original prime meridian was set by various countries in response to the need to determine their position.

With the development of the maritime industry, this situation of "separate affairs" gradually changed. In 1767, Mascalin, director of the Greenwich Observatory in the United Kingdom, compiled the British Nautical Astronomical Calendar, which uses the Greenwich meridian as the zero meridian of the earth and the celestial sphere. Soon after the publication of the book, it was adopted by many young people.

In 1871, the first International Geographical Society was held in Antwerp, Belgium, and it was decided that "the Greenwich meridian should be used as the zero meridian in all countries, and it should be implemented within 15 years".

At the 7th International Geodesy Conference held in Rome in October 1883, it was decided that "the prime meridian must be the meridian through a first-class observatory, and in view of the fact that 90 percent of the seafarers engaged in overseas ** have used the Greenwich meridian as the reference to calculate the position (longitude) of the ship, the Greenwich meridian shall be used as the prime meridian by all countries." On the question of timing, it was considered that:

This would be of great convenience when a unified world should be adopted in international interactions.

On October 1, 1881, the International Meridian Conference was held in Washington, D.C., USA. In the end, the General Assembly adopted seven resolutions, among which:

Resolution 2: States present at the meeting ** shall adopt the prime meridian through the center of the meridian ring of the Greenwich Observatory.

Resolution 4: Advocate the use of universal time, and local time or standard time can also be used if needed.

Resolution 5: World Day begins at midnight on the prime meridian, and civil days begin at midnight.

By this time, the prime meridian and universal time were finally established and recognized by most countries.

The prime meridian, or 0 degree meridian, also known as the Greenwich meridian or Greenwich meridian, is a meridian (also known as meridian) located at the Greenwich Observatory in the United Kingdom. The east and west sides of the prime meridian are set as east and west longitudes, respectively, and meet at 180 degrees.

Prime meridian (**** in the network).

But where does the prime meridian come about?

The world-famous Gora Rinnich Observatory was built in 1675. At that time, the seafaring industry in Britain was developing rapidly. In order to solve the need to measure longitude at sea, the British authorities decided to build an observatory in the Royal Greenwich Gardens on the banks of the River Thames, about 20 kilometers from the city center in the southeastern suburbs of London.

Greenwich Observatory (**** on the Internet).

After 1835, the Greenwich Observatory was expanded and updated under the leadership of the brilliant astronomer Eri. He pioneered the use of the "meridian ring" to determine Greenwich Mean Solar Time. It became the most advanced astronomical observatory in the world at that time.

Meridian Ring (**** on the Internet).

With the development of the world's maritime industry, many countries have established observatories to measure local time. Internationally, in order to coordinate the measurement of time and determine the geographical longitude, the International Longitude Conference was held in Washington in 1884. The meeting decided to pass the meridian of the Greenwich Observatory at that time as the standard reference meridian for the global time and longitude meter, called the 0 meridian or prime meridian.

Prime meridian (**** in the network).

Since then, not only have maps published by various countries use this line as the starting point of geographical longitude, but also use the Greenwich Observatory as the starting point of the "world time zone", and use Greenwich chronometers to calibrate the time.