Johannes Kepler and his Mother's Trial for Witchcraft


The story of how Johannes Kepler caused his mother to be accused of being a witch.

In 1615 Johannes Kepler, one of history's great astronomers, was at the peak of his powers having recently written his Laws of Planetary Motion building upon the work of Nicolas Copernicus and further adding to the proof of the heliocentric model of the solar system.

Working as the imperial mathematician for the Holy Roman Emporer Rudolph II, in 1620 he disappeared and abandoned his work to defend his mother, Katharina who had been accused of witchcraft, a crime that if found guilty would have led to her execution.

In 1600s Europe, a series of witch trials were sweeping the continent with 75,000 accused of being witches, the majority of them women. Of these, 50,000 were found guilty and executed. Following accusations, by 24 members of her village, Katharina Kepler was accused of being a witch and chained to the floor of a prison cell.

Kepler, recognising the seriousness of the charge left his work to defend her during the 6 year ordeal. Using logic and reasoning he dismantled the prosecution's case piece by piece and Katharina was found not guilty but forbidden to return to her village dying 6 months later.


Kepler race to his mother's aide was in stark contrast to his siblings who abandoned and disowned their mother. It was later theorized that he felt guilt as he may have inadvertently caused her accusations - he wrote a book 5 years before the accusations that told the story of an astronomer who went to the moon with the help of his witch mother. The story, whilst never published, found its way back to Katharina's village with Kepler later stating it "was was taken up by senseless minds, it flared up into defamation, fanned by ignorance and superstition".


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