Value of the Prime Meridian
The meridian passing through Greenwich, England, is called the Prime Meridian. The eastern part of the Earth's main meridian is called the Eastern Hemisphere, while the western part is known as the Western Hemisphere. The Prime Meridian is a random value, which represents that it can be determined anywhere.
When the Sun is at the highest point in the sky in Greenwich, all places along this meridian will have a meridian or noon. The Prime Meridian helps determine the time zones of countries. Time increases at the rate of four minutes per one degree of longitude. Lastly, the Prime Meridian is the starting point for measuring the distance of the Earth from both east and west.