What on earth is down there?

If you've ever gazed out of an airplane window as you flew over the U.S. and wondered what exactly was down there, you might be interested in America from the Air, an ambitious new book by Daniel Mathews and James S. Jackson. It combines aerial photography of interesting sites found along many of the nation's flight paths with detailed descriptions of the areas.

For instance, passengers flying over southern Michigan might glimpse the sprawling proving grounds where auto manufacturers put prototypes through their paces. The book's picture of the area, reminiscent of spy satellite reconnaissance photos, highlights several features of the complex, while the accompanying text gives a brief history of the U.S. auto industry and its rise to prominence in nearby Detroit. Another entry explains what those circles are in the patchwork quilt of farmland in the nation's breadbasket.

To help you locate these geographic features, the book (which comes with a CD for in-flight laptop use) has maps showing the air routes with cross-referenced page numbers alongside them. While you may not actually spot features you're searching for, it can be both fun and fascinating to know what you're flying over-and as such, this book could make those hours in the air go by just a little faster.