(© copyright 1996-1999, Timothy G. Feeman and Elaine F. Bosowski.)
This page shows an illustration of the navigation exercise you will conduct in Homework Exercise #6. In this illustration we create an approximation to the shortest route from Villanova University (40 deg N, 75 deg W) to Helsinki, Finland (60 deg N, 25 deg E).
In the first picture, we use a gnomonic projection. Villanova and Helsinki are located and marked, and the straight line connecting them is drawn. This line represents the actual shortest route between the two places. We then locate three intermediate point along the route. These are labelled as P1, P2, and P3.
Next, we take a Mercator map and locate and mark Villaonva University, Helsinki, and
the points P1, P2, and P3. The straight lines connecting these points are drawn. Each of
these lines corresponds to a single compass bearing which we measure clockwise from the
North. Her is the picture:
Thus, we can approximate the shortest route by a route that requires only four different compass bearings -- 37 deg from North from Villanova to P1, then 54 deg from North from P1 to P2, then 74 deg from North from P2 to P3, and finally 117 deg from North from P3 into Helsinki.