Prime+Meridian

=Prime Meridian= ====The Prime Meridian is the line that separates the eastern and western hemispheres (with the 180th meridian). It is also known as 0° longitude. The prime meridian goes through an observatory in Greenwich, which is a popular tourist attraction.====

at the Royal Observatory in Greenwich
The Prime Meridian is at 0°, but that means it's only on one side of the earth. There is a line similar to the Prime Meridian called the 180th meridian (or antimeridian), which is at 180°. It opposes the Prime Meridian, and also is on the same side as the International Date Line. They both complete the circle needed to separate the eastern and western hemispheres. The Prime Meridian also opposes the Equator, which is at 0° Latitude. The Prime Meridian measures at approximately 20,003.93 km, stretching from the north pole to the south pole

BY IMAN