The longitude is an arbitrary line used along with the latitude in a geographical coordinate system to specify a location of a point on the surface of the Earth. For a point on the surface of the Earth, the longitude is the line that runs from north pole to the south pole through it. Longitude also specifies the west to east angular displacement of the point of interest on a latitude relative to the reference longitude called the prime meridian. The prime meridian on Earth passes through the Royal Observatory at Greenwich, England and is defined at 0°. The longitude is then measured +180° towards the east and -180° towards the west from there. The longitude meridians are separated at 1° intervals, which correspond to 60 minutes. For precision, these 60 minutes are further divided into 60 seconds. These intervals can be observed practically in the world as time zones.
Frequently Asked Questionsedit
How to calculate the longitude of a location?edit
The longitude of a location can be found by finding the difference between the local mean time and the Greenwich mean time. Without a local reference of time or a clock in your location, finding the longitude is quite impossible. There was even a system of rewards by the British government known as the Longitude rewards, for the people who could accurately measure the longitude of a ship at sea. To know how to find latitude, read this answer.