Chapter 7: A Plumb Line to the Sun Summary and Analysis

Copernicus and Kepler measured the distances of the solar system which were expressed in astronomical units or the distance of the earth to the sun. However, the actual value of the astronomical unit had not been determined. There were two methods of determining those distances: micrometry and triangulation. Using micrometry, the astronaut used a micrometer, a device with a special eyepiece to measure the size of a planet as seen through a telescope. Triangulation to determine the parallax of a celestial object, was accomplished through the observation of a planet from two different perspectives on the planet. The data was then compared and calculations were arrived at through euclidean geometry.

Advancements were being made in both cartography and chronometry at a time when fortunes were being made at sea...