What is a Great Circle?

A straight line drawn between two places on a world map looks like the shortest distance between them. But this usually isn’t so, because most maps are distorted. Take a look at a globe. If you stretch a piece of string over the globe, joining Japan and Denmark, you will see that the shortest route runs over the North Pole, not from east to west. The curved line joining Japan and Denmark is part of a Great Circle. This is any circle that divided the globe into two equal halves. Aircraft and ships often follow Great Circle routes.