141 years ago today, on October 13, 1884 (August 25, 1884 lunar calendar), Greenwich international standard time was born. The picture shows the standard clock at the Greenwich Observatory on the outskirts of London, the capital of the United Kingdom. October 13 is international standard time day. On October 13, 1884, the International Conference of Astronomers held in Washington decided to use the longitude through Greenwich, southeast London, England, as the prime meridian, as the starting point for calculating geography and the starting point of the world standard "time zone". Later, October 13 was designated as international standard time day every year. In 1884, the International Conference of Astronomers decided to use the line of longitude passing through Greenwich as the prime meridian as the starting point for calculating geographical longitude and the starting point of the world's standard "time zone". On October 13, Greenwich Mean Time was officially adopted as international standard time. The establishment of Greenwich Mean Time was related to a dispute in England: on November 24, 1858, the clocks in Dorset, England, indicated that at 10:6 am, a county judge ruled against a person who brought a land lawsuit because he was not on time for the 10am hearing. The man arrived in court two minutes later, and he pointed out to the judge that according to the clocks at the railway station in his hometown of Carlisle, Kemberland, he had arrived on time. The case must therefore be retried. The discrepancy between the time of the railway station and the court prompts the British government to unify the time. In addition, Britain is a country with a very developed maritime industry, and it is a matter of life and death for navigators to be able to time accurately. Without accurate timing tools, it is impossible to know the location and time of a ship's voyage in the ocean. When a ship is at sea, its position is calculated from the latitude and longitude. For a long time, navigators have only guessed the longitude and determined the course based on sailing experience. If it is wrong, the ship will go wrong, and even run aground or hit a rock. Such accidents are not uncommon in the history of navigation. In 1707, a British fleet led by Sir Crossley was wrecked due to a wrong longitude measurement, destroying four ships and killing more than 2,000 people. To solve the problem of measuring the longitude of navigation, as early as 1675, King Charles II of England ordered the construction of an observatory in Greenwich Village on the River Thames southeast of London. After more than a hundred years of hard work, astronomers finally developed a scientific timekeeping method, and used the meridian drawn through this observatory as the starting point of the geographical longitude measurement and timekeeping system. As long as the meridian line of the Greenwich Observatory is the starting point, sailors around the world can accurately determine the correct position and time of their ships during voyage. The scientific research of the Greenwich Observatory has contributed to the prosperity of maritime shipping and the avoidance of maritime accidents. When the Greenwich Observatory determined its own meridian, some countries in the world also determined their own meridian according to their own geographical conditions, which is easy to cause confusion. To solve this problem, on October 13, 1884, representatives of more than 20 countries held a meeting in Washington, USA, and made a resolution on the use of a unified international standard time and a unified meridian: "The meeting recommended to the governments of the participating countries that the meridian through the meridian center of the Greenwich Observatory should be defined as the prime meridian of longitude." Therefore, the meridian through the Greenwich Observatory was recognized by the world as the prime meridian, as the starting point for calculating the geographical longitude and the starting point of the world's "time zone", and the Greenwich international standard time was born. Greenwich Mean Time is a time scale based on the earth's rotation. Later, it was found that the earth's rotation has a gradual trend of slowing down, with seasonal changes and sudden irregular changes. Therefore, at the World Radio Administrative Conference held in Geneva in late 1979, a resolution was passed to replace Greenwich Mean Time with "Universal Coordinated Time" as the international standard time in the field of radio communication. This development reflects the rapid development of science and technology in today's world. Comment: China is increasingly in line with the world