Eighty years ago, the May 15, 1939, issue of Life Magazine introduced readers to the sometimes counter-intuitive geography that comes from living on a globe. In particular, the magazine noted that it was important for shortwave broadcasting.  For example, it pointed out that the first reaction on how to reach Manila from New York would be to point the antenna toward Mexico and the Pacific.  But by looking at a globe or an azimuthal map centered on New York, it’s clear that the shortest path is over Alaska.

Similarly, the magazine notes that it’s easier for Berlin radio to reach South America than it is for New York.  This is because to reach the entire continent, the American station needs to have a beam 40 degrees wide.  The German station, on the other hand, can get by with only half the power, since most of the continent can be covered with a beam of only 20 degrees.

It’s not a coincidence that New York and Berlin were chosen as the examples.  Shortwave radio was an important force in World War II.  For more information, see our earlier post.