When was greenwich chosen as the prime meridian

In , in the midst of the reformation period, King Charles II founded the Greenwich Observatory in the Crown-owned Greenwich Park, south east London, to improve naval navigation and establish longitude measurements using astronomy. The Scilly naval disaster prompted further action in the pursuit of measuring longitude.

However, it was not until that the Board awarded the prize to John Harrison, a joiner and watchmaker from Yorkshire , for his mechanical timepiece the marine chronometer, which overtook the lunar method in its popularity for establishing longitude with nineteenth century sailors.

Intrinsically linked to the measurement of longitude is the measurement of time. Until the end of the nineteenth century, there were no national or international guidelines for measuring time. This meant that beginning and end of the day and the length of an hour varied from town to town and country to country. The advent of the industrial age in the mid — late nineteenth century, which brought with it the railway and increased international communications, meant an international time standard was needed.

Twenty-five nations attended the conference in total, and with a vote of 22 to 1 San Domingo was against and France and Brazil abstained from voting , Greenwich was chosen as the Prime Meridian of the World. Greenwich was chosen for two important reasons:. Decisions made at the conference were in reality only proposals and it was the responsibility of individual governments to implement any changes as they saw fit.

The difficulty in making universal changes to the astronomical day was also a hindrance to progress and whilst Japan adopted GMT as of , other nations were slow to follow suit. It was once again technology and tragedy which prompted further action at the beginning of the twentieth century. Governments did not always agree that the Greenwich meridian was the prime meridian, making navigation over long distances very difficult.

Different countries published maps and charts with longitude based on the meridian passing through their capital city. France would publish maps with 0 longitude running through Paris. Cartographer s in China would publish maps with 0 longitude running through Beijing. Even different parts of the same country published materials based on local meridians.

Finally, at an international convention called by U. President Chester Arthur in , representatives from 25 countries agreed to pick a single, standard meridian. They chose the meridian passing through the Royal Observatory in Greenwich, England. The Greenwich Meridian became the international standard for the prime meridian. UTC never changes for daylight savings or anything else.

Just as the prime meridian is the standard for longitude, UTC is the standard for time. In the past, GMT has been used with two different conventions for numbering hours. The long-standing astronomical convention, dating from the work of Ptolemy, was to refer as zero hours and, on the other hand, the civil convention referred to midnight as zero hours dating from the Roman Empire.

In , the latter convention was then adopted for astronomical purposes, resulting in a discontinuity of 12 hours, or half a day. The instant that was designated "December However, later GMT was adopted by astronomers so that the astronomical day began at midnight, the same time as the civil day. Some confusion in terminology resulted, however, in the International Astronomical Union changed the designation of the standard time of the Greenwich meridian to Universal Time.