Great-circle route is the shortest, most direct route between two points on the earth's surface. A great circle is any circle that divides the globe into equal halves. Its length is the same as that of the equator. On most flat maps, a straight line appears to be the shortest distance between two places. A great-circle route often appears as a longer curve. But maps are not true pictures of the surface of the earth. Maps are flat, but the earth is a sphere. The shortest distance between any two points on the earth can be found easily only on a globe. The shortest distance lies along the great circle passing through the two points. A special kind of map called a gnomonic projection shows a great-circle route as a straight line.