Originally published in 1907 as a section of the author’s larger “Great Astronomers,” this Kindle edition, equivalent in length to a physical book of approximately 16 pages, describes the life and work of early 17th century German astronomer Johannes Kepler, who discovered the laws that govern planetary motion.
Sample passage:
When Kepler had before him that wonderful series of observations of the planet Mars, which had been accumulated by the extraordinary skill of Tycho, he proved, after much labor, that the movements of the planet refused to be represented in a circular form. Nor would it do to suppose that Mars revolved in one circle, the center of which revolved in another circle. On no such supposition could the movements of the planets be made to tally with those which Tycho had actually observed. This led to the astonishing discovery of the true form of a planet’s orbit. For the first time in the history of astronomy, the principle was laid down that the movement of a planet could not be represented by a circle, nor even by combinations of circles, but that it could be represented by an elliptic path. In this path the sun is situated at one of those two points in the ellipse which are known as its foci.
About the author:
Sir Robert S. Ball (1840-1913) was professor of astronomy and geometry at Cambridge University, and was Royal Astronomer of Ireland. Other works include “In Starry Realms” and “In the High Heavens.”
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