How is longitude measured on a globe?

Longitude is measured from the Prime Meridian, which is designated as 0 degrees longitude, extending to the east and west around the globe. This east-west measurement allows for the identification of a location's position relative to that central meridian. Coordinates of longitude are expressed in degrees, with values ranging from 0 degrees at the Prime Meridian to 180 degrees east and west.

In the context of navigation and mapping, understanding longitude is crucial for accurately pinpointing locations on Earth's surface. The other concepts of measurement, such as north and south (which refer to latitude), above and below, or diagonal do not accurately describe how longitude is defined or measured. Therefore, recognizing that longitude is fundamentally about east-west orientation is essential for understanding global positioning.