ABSTRACT
As you read the last two chapters some questions may have occurred to you. And the answers to these questions may generate other questions. Here are some that come up frequently.
A map is a two-dimensional scale model of the surface of the Earth. But models can take many forms, including mathematical. Due to the nature of nature, as elucidated by Isaac Newton and Johannes Kepler, the position of a satellite at any time may be predicted with a high degree of accuracy by a few mathematical equations. A satellite orbiting the Earth may be modeled by formulas contained in the memory of the microcomputer in the receiver. When the formulas are applied to bodies at the high altitudes of the GPS satellites, where they are free from atmospheric drag, the formulas are relatively simple and can predict the position of the satellite quite accurately.
