Définition
Le méridien de Greenwich est une ligne imaginaire qui va du pôle Nord au pôle Sud, en passant par l'Observatoire royal de Greenwich, à Londres, en Angleterre. Il est également connu sous le nom de méridien d'origine et est utilisé comme ligne de référence pour mesurer la longitude sur Terre.
Longitude is a measurement of how far east or west a point on the Earth's surface is from the Prime Meridian. By convention, the Prime Meridian is designated as 0 degrees longitude, and all other longitudes are measured in degrees east or west of this line, up to 180 degrees.
The Greenwich Meridian was first established as the Prime Meridian in 1884, at an international conference held in Washington D.C. This decision was made because the Royal Observatory in Greenwich had long been a center for scientific research and was a well-established reference point for navigation.
Here are some examples of how the Greenwich Meridian is used:
- Time zones: The world is divided into 24 time zones, with each zone covering 15 degrees of longitude. The time in each time zone is based on the position of the sun relative to the Prime Meridian.
- Navigation: The Greenwich Meridian is used as a reference point for navigation on land, sea, and air. It helps to determine the position of a ship or plane, and to calculate the distance and direction to a destination.
- GIS (Geographic Information Systems): GIS technology uses the Greenwich Meridian as a reference point to create maps and analyze spatial data. This helps to visualize and understand geographic patterns and relationships.
In summary, the Greenwich Meridian is an important reference line used to measure longitude on Earth, and it has numerous practical applications in navigation, timekeeping, and geographic information systems.
