Witchcraft and the Laws of Planetary Motion

reverenderik (42)in #history • 7 years ago

From the "Is Progress a Real Thing?" Department: while Johannes Kepler was busy working out his Third Law of Planetary Motion, his 68 year-old mother was busy being accused of witchcraft and even thrown in prison for a little while.

Katharina Kepler was a healer and herbalist and also very grumpy. Apparently she didn't get along very well with her neighbors, because some of them accused her of witchcraft. Meanwhile, her son was busy rewriting our understanding of the world we live in.

Johannes Kepler was a contemporary of Galileo. Kepler's Three Laws of Planetary Motion are still used today. He was able to figure out things about the speed of a planet's orbit around the Sun and the shape of its orbit without understanding gravity. Heck, he was able to calculate this stuff before the invention of calculus. His innovation and genius are difficult to wrap your head around today.

His third law deals with the harmonics of a planet's orbit and it's sort of difficult to understand. It's stated thusly: "The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit." Kepler was kind of obsessed with planetary harmonics. His vision of the solar system involved relationships between nested virtual Platonic solids -- a vision which I will happily admit to not understanding very well. I'd encourage you to read more about Kepler and his ideas! He really was one of the most influential astronomers in history, and we owe a lot to his work.

Johannes Kepler by an unknown artist, 1610, from Wikimedia.