The first law - treading lightly

My first law states that planets move around the sun in an elliptical orbit with the sun at one focus of the ellipse.  I realize this seems simple enough, especially when stated so succinctly.  But believe me when I say it took a lot of time and energy to arrive at such a conclusion.

As stated last time, I began by piecing together the clues discovered by my predecessors.  The Greeks, famous for their geometry and other Pythagorean legacies, believed a particular idea known as "harmony of the spheres."  Their worldview was such that the world had perfect organization and order; indeed this extended to the heavens.  Having detected at least some extraterrestrial objects, the Pythagorean's in particular proposed that the earth was spherical (perfectly shaped object!) and these discovered objects revolved with the earth about a central fire - the sun.  Not only so, but the different heavenly objects were separated from one another by spherical intervals of harmonic lengths.  The movement of the spheres, therefore, was thought to produce a beautiful musical arrangement known as the "harmony of the spheres."  I marvel at the wonder and intellect that generated such a notion!

I interpreted the "harmony of the spheres" through the lenses of Copernicus and Brahe, and added to it some other geometrical shapes that I hypothesized would be involved, which resulted in the representation shown below (also in the updated edition of Mysterium Cosmographicum).  However, in the early 1600s I abandoned the picture perfect idea, to the dismay of many, because the numbers just weren't adding up.  Once I derived accurate calculations of the earth's orbit (from Brahe's observational data), I turned my attention towards Mars, the planet nearest earth.  My calculations showed that the center of Mars' presumably circular orbit was not equidistant from the planet itself.  At the aphelion and perihelion (the points where the planet is farthest from the sun and closest to the sun, respectively) the measurements from the planet to the estimated center were distinctly larger than the measurements during the rest of the planet's orbit.  Thus, at least one thing was for certain - the shape of the orbit was not circular or spherical in nature.  Now, it is important to note here that treading lightly is a critical skill to practice when your newly found information rails against essentially everything (i.e. the perfect order of the universe and the earth within it) the most influential people and institutions have held dear for millennia.  So instead of getting my name out there I focused on solving the answer to the question that this presented - if planetary orbits weren't circular, then what were they?

Enter William Gilbert's 1601 publication On Magnets, and the plot thickens.  Gilbert's musings highlighted the fact that not only did I care about the shape of planetary orbits, but I also wondered how in the world (pun intended 😉) these celestial spheres remained suspended in space, in their respective patterns, accomplishing the remarkable feat of circumnavigating die Sonne, as we Germans say.  My spiritual leanings made me happy to hypothesize that there was a perfectly good reason, or better yet, Logos, perhaps radiating from the sun that acted on satellites in such a way that everything just held together (see Colossians 3:17).  Regardless of the reason, it was clear, after about two years of laborious calculations (which can be examined elsewhere), that the orbital curves precisely resembled ellipses.  Hence, I arrived at the now succinct first law of planetary motion with which I started, as pictured below.

Sources:

1. https://www.oakweb.ca/harmony/pythagorean/pythagorean.html

2. http://www.keplersdiscovery.com/Harmonies.html

3. A History of Mathematics: An Introduction (Second Edition), by Victor Katz
4. http://radio.astro.gla.ac.uk/a1dynamics/ellproof.pdf
5. http://oneminuteastronomer.com/8626/keplers-laws/