The Great Circle

This applet shows the great circle route and the great circle distance between a number of cities around the globe. Click and drag to rotate the globe.

To see the route and distance between any two cities on the map, simply click on the red dots representing the two cities. Two routes are shown. The green route is the smaller arc of the great circle containing your two cities. The approximate great circle distance is shown in the box at the upper left corner.

Below the globe is the familiar Mercator map of the world, the kind often printed in books and world atlases. When you click on two cities on the globe, the straight-line route on the Mercator map appears in red, and the same route is plotted on the globe so you can compare the Mercator route (red) with the great circle route (green). By rotating the globe, you should be able to observe that the great circle route is the shortest path between your cities on Earth's spherical surface.