Answer: A Dutch living room
In the Dutch town of Franeker, there is a small and inconspicuous house with houses a planetarium on the ceiling of his living room. The complex and mechanically driven model of our solar system is over 230 years old and, as such, the oldest functioning planetarium ̵
How exactly did a small house in the Netherlands become a planetarium? To answer this question, we have to deal with the story of a brilliant Dutch astronomer called Eise Eisinga. As the son of a woolen worker Eisinga was not allowed to go to school, but had to study the craft of his father. Nevertheless, he continued his education and published his first astronomical works at the age of 17. Later, he was even a professor at the Franeker Academy.
Eisinga began work on his planetarium in the summer of 1774. That same year, Reverend Eelco Alta published a book claiming that an imminent conjunction of the Moon with the planets Mercury, Venus, Mars, and Jupiter would cause all five The cosmic body would collide and the earth would be displaced by its orbit and burned by the sun. This prediction sparked excessive public panic, and Eisinga, as a service to the public, began working on a complicated model of the solar system to show that the forecast and its predicted outcome were wrong.
The Whole The project lasted 7 years (much more than the 6 months originally predicted by Eisinga) and involved a complex system of wooden rings that were equipped with thousands of hand-forged nails as tooth-teeth. Despite its age, the apparatus still tracks the placement of planets in our solar system with precision – a testament to both the quality of the construction and the builder's knowledge.