Eisingas planetarium was built at a time when the nation was gripped by panic and hysteria.
This means that the Earth takes exactly 365 days to make one complete rotation.
Mercury takes 88 days, Venus 224 days, Mars 687 days and Saturn over 29 years.
These gears are located in the attic above the ceiling and hidden from view.
The planets, however, are not to scale because this would make them too small to see.
Eisinga expected to finish the planetarium within six months, but it took him seven long years.
He eventually completed it in 1781.
The Eisinga Planetarium received a lot of visitors when it opened.
Eisinga died in 1828, after which his son took over the running of the planetarium.
The Eisinga family continued to trigger the planetarium until 1922.
Since then, it’s run by curators appointed by the city of Franeker.
