Johannes Kepler mathematically described how the planets move and laid the groundwork for Newton’s gravity, yet he also cast horoscopes for emperors, believed the Earth had a soul, and wrote a science fiction story that became evidence in his own mother’s witchcraft trial. This episode traces his life from a childhood of smallpox-damaged eyesight and an absent mercenary father, through theology studies at Tubingen, to the 1596 Mysterium Cosmographicum, an elegant but wrong model nesting the five Platonic solids between the planetary orbits.

We follow his exile as a Protestant, his tense partnership with Tycho Brahe in Prague, the 1604 supernova that dismantled Aristotle’s unchanging heavens, and the years-long war on Mars in which he recalculated the orbit 40 times before abandoning the circle for the ellipse. We cover the deaths of his wife and son, his algorithmic search for a second wife among 11 candidates, the defense he mounted for his mother Katharina, and the third law hidden inside the 1619 Harmonices Mundi, written as he searched for the literal music of the spheres.

• How poor eyesight pushed Kepler to trust mathematics over observation and become a theorist
• Why an eight-arc-minute discrepancy in Tycho’s Mars data led him to discard 2,000 years of circular orbits
• How his novel Somnium, with its demon-guided trip to the moon, fed the witchcraft accusations against his mother
• What the equal-areas law and the T-squared-to-R-cubed relationship revealed about a unified solar system
• Why Galileo and Descartes ignored his laws until Newton used them to derive universal gravitation