The Greenwich Meridian is an imaginary line that runs from the North Pole to the South Pole, passing through the Royal Observatory in Greenwich, London, England. It is also known as the Prime Meridian, and it is used as a reference line for measuring longitude on Earth.
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:
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.