Franeker, Dronrijp

During your cycle route through Franeker and Dronrijp, you'll discover Eise Eisinga's life story and pass the Royal Planetarium, added to the UNESCO World Heritage List in September 2023. It is the oldest working planetarium in the world!

Eise Eisinga (21 February 1744, Dronrijp) grew up as a highly gifted boy. Although he had to work in his father's wool combing business, he also adopted his father's interest in astronomy and arithmetic. From an early age, he walked weekly to Franeker, where he studied Euclid's mathematics books at the University of Franeker (1585-1811). Today, the Franeker Academy, as it is now called, can be found at Breedeplaats 1 in Franeker.

Eise learned all facets of astronomy thanks to many hours of self-study. He was also immensely interested in sundials. He published a book with drawings of some 150 sundials.

In 1774, a Frisian minister from Bozum published a booklet in which he predicted that as soon as four planets aligned with the moon, the earth would be thrown out of its orbit and burn in the sun. This caused much unrest in Friesland. Eisinga, as a supporter of the Enlightenment, subsequently decided to build the planetarium. That way, he knew what was happening in the sky at any time of day.

In seven years, he rebuilt the universe on the ceiling of his living room. The planets orbit the sun in the same number of days they do in real life. An impressive cog of wooden hoops, nine weights and 5,934 hand-forged nails and teeth, set the system in motion.

Besides being a supporter of the Enlightenment, Eisinga was also a patriot and opposed the ideas of Stadholder William V. This caused him to be arrested and banned from entering the province for five years. When he was released again in 1818, King William I visited his planetarium. He was so impressed that he bought it for the Dutch state. It was later donated to the municipality of Franeker.

Eisinga left the instructions and operation of the planetarium in his will. To this day, the planetarium is still operated using these instructions, for example for the manual transmission of the leap day 29 February. Eise Eisinga died on 27 August 1828 at the age of 84.