Since ancient times, humans have sought ways to accurately locate their position on the planet. To do this, the creation of imaginary lines such as meridians has been fundamental. In this context, the reference meridian, Also called zero meridian, has played an essential role in the measurement of length and the organization of global time.
This current reference meridian is the Greenwich Meridian, which was officially adopted in the 19th century. Its establishment allowed the standardization of maps and the creation of time zones, greatly facilitating navigation and international trade. But how did Greenwich come to be the global reference point? In this article, we will explore its history, its importance and some curiosities related to this meridian.
What is the Greenwich meridian?
El Greenwich Meridian It is an imaginary line that joins the North Pole with the South Pole and crosses the Royal Greenwich Observatory in London, United Kingdom. It is known as the 0° meridian, since it is used to measure the longitudes to the east and west of the planet.
Before its official adoption, there were multiple reference meridians used in different countries, which caused problems in navigation and trade. To solve this situation, 1884 was carried out Meridian International Conference in Washington DC, where representatives of 25 countries They decided that the meridian passing through the Royal Observatory, Greenwich, would be the world reference meridian.
History of reference meridians
Before Greenwich, several places were proposed as reference points for measuring longitudes. The ancients cartographers y navigators They used to use different starting points, such as Paris, Roma and even Jerusalem. One of the most used in Europe was the meridian of El Hierro, In the Canary Islands, which had been established in the 17th century.
However, with the expansion of the British Empire and the importance of maritime trade, Greenwich became a key reference point. In the International Meridian Conference of 1884 The need to unify the global reference point to avoid confusion was raised. The choice of Greenwich as the prime meridian was driven by British hegemony in navigation and trade at the time.
Importance of the Greenwich meridian
El Greenwich Meridian not only serves as geographical reference, but it is also key in defining the time zonesFrom this meridian, the Earth is divided into 24 time zones de 15° longitude each, thus establishing a universal time system.
In addition, Greenwich served as the base for the creation of the Greenwich Mean Time (GMT), which until 1972 was the world time standard. Today, GMT has been replaced by the Coordinated Universal Time (UTC), which uses atomic clocks for greater precision.
Why does the GPS system use another meridian?
Interestingly, the system GPS (Global Positioning System) does not use exactly the as its primary reference. Instead, it uses the International Reference Meridian (MRI), which is located approximately 102 meters east from the Greenwich meridian.
This shift is due to the fact that GPS satellites use a system of Coordinates more accurate than correcting errors in traditional astronomical measurements. The difference is small and only affects extremely precise measurements, but it makes a noticeable difference in studies geodesics.
Countries through which the Greenwich meridian passes
El Greenwich Meridian It crosses several countries from north to south. These include:
- United Kingdom – Home of the Royal Greenwich Observatory.
- France – It crosses different regions of the country.
- Spain – It passes through the eastern part of the Iberian Peninsula.
- Algeria – Continue through North Africa.
- Mali, Burkina Faso, Togo y Ghana – It crosses these African countries before reaching the Gulf of Guinea.
Additionally, the meridian follows its trajectory to the Antarctica, crossing the Atlantic Ocean and the South Pole.
El Greenwich Meridian It has been fundamental to navigation, cartography, and timekeeping. Its adoption allowed for the standardization of geographic coordinates and created the basis for the time zone system we use today. Although GPS has adjusted its reference to a slightly different meridian, Greenwich remains a key reference point for geography and history of humanity
