If you have ever looked at a globe, you have seen the vertical lines running from the North Pole to the South Pole. The most important of these is the Meridian Line —specifically, the Prime Meridian .
But what exactly is a meridian, and why does it matter? In geography and astronomy, a meridian is an imaginary semicircle that runs from the North Pole to the South Pole. Every point on Earth that lies along the same meridian experiences solar noon (when the sun is at its highest point in the sky) at the same moment. meridian line