Together, these imaginary vertical lines run from the North Pole to the South Pole, dividing the Earth like the segments of an orange to help us pinpoint any location on the planet. 1. Defining the Terms
| Feature | Description | | :--- | :--- | | | Runs North-South (Pole to Pole). | | Measurement | Angular distance East or West of the Prime Meridian. | | Values | 0° to 180° East, and 0° to 180° West. | | Reference Point | The Prime Meridian (Greenwich, UK). | | Key Characteristic | Meridians converge at the poles; they are not parallel. | | Primary Use | Determining East-West position and calculating local time. | meridian longitude
For longitude to be measurable, a zero point is necessary. Today, that zero point is the , which runs through the Royal Observatory in Greenwich, England . Established by international agreement in 1884, the Greenwich Meridian is designated as 0° longitude . Together, these imaginary vertical lines run from the
The problem: pendulum clocks were useless on rolling ships. The British government offered the (worth millions in today’s money) for a practical solution. It was won by John Harrison , a self-taught clockmaker who built rugged marine chronometers in the 18th century. | | Measurement | Angular distance East or