Prime meridian

Prime Meridian

The Prime Meridian is the meridian (a line of longitude) in a geographical coordinate system at which longitude is defined to be 0°. Together with its antimeridian, the 180th meridian, which lies 180° longitude away, they form a great circle dividing the Earth into the Eastern and Western Hemispheres.

History

The Prime Meridian was established by Sir George Biddell Airy in 1851 at the Royal Observatory, Greenwich where the marked line is found. The decision was made by the International Meridian Conference on October 13, 1884. The conference selected the meridian passing through the Royal Observatory as the official Prime Meridian due to its popularity. However, France abstained from the vote and French maps continued to use the Paris Meridian for several decades.

Modern references

In the Global Positioning System (GPS), the Prime Meridian is defined by the World Geodetic System (WGS 84). The older Greenwich Mean Time (GMT) sometimes has its own name, used to avoid confusion with "GMT" in the aviation, computing, navigation, weather forecasting, and many other fields.

See also

• International Date Line
• 180th meridian
• Greenwich Mean Time
• Geographical distance
• Geographical coordinate system

External links

• The Royal Observatory, Greenwich

Prime meridian Resources
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