Meridian

Definition

A meridian refers to a line of longitude, running from the North Pole to the South Pole and measuring distance east or west from the Prime Meridian.

Analogy

If parallels are like rungs on a ladder, meridians are like slices in a pizza. Each slice represents a different range of longitudes, with the Prime Meridian being one edge of your favorite slice.

Related terms

Prime Meridian: This is our "zero" point for measuring longitude. It's an imaginary line that runs from the North Pole to the South Pole through Greenwich, England.

Greenwich Mean Time (GMT): This is time at the Royal Observatory in Greenwich, London which lies on Prime Meridian and it serves as reference time for many countries.

International Date Line: An imaginary line of longitude on Earth's surface located at about 180 degrees east (or west) from the Prime Meridian. It's like if you took your pizza and flipped it around - this would be your new edge slice.