Franeker's Planetarium: An 18th Century Astronomical Model Built by a Wool Merchant
August 24, 2026 · Frisian News
Wool merchant Eise Eisinga built a mechanical planetarium in his Franeker home starting in 1774 to show his neighbors how the planets orbit the sun. Today, nearly 250 years later, the model still works, making it one of the world's oldest functioning astronomical devices.
In the town of Franeker sits a house filled with brass wheels, wooden beams, and an intricate mechanical dance of the heavens. Eise Eisinga, a wealthy wool merchant, built this planetary model starting in 1774 and spent seven years perfecting every detail. Today, the Eisinga Planetarium remains one of the oldest working astronomical devices in the world, a testament to the ingenuity of an 18th-century Frisian businessman.
Eisinga built his planetarium at a time when fear gripped many people across Friesland. Panic spread through towns and villages over fears of astronomical catastrophe. Some townspeople believed such a catastrophe would destroy everything they knew. Eisinga, who studied mathematics and astronomy, understood the truth. He decided the best way to ease people's worries was to build a working model that anyone could see and understand.
The planetarium is a mechanical marvel. Suspended from the ceiling and filling much of the front room, it shows the sun at its center with all the known planets orbiting around it in their proper paths. Thousands of brass gears and wheels mesh together with perfect precision to move each planet at the correct speed.
Eisinga never grew famous for the planetarium during his lifetime, yet visitors came from across Europe to see his creation. Scientists and curious travelers made the journey to Franeker to study the mechanical model. Eisinga ran his wool business and maintained his beloved planetarium for the rest of his life.
The Eisinga Planetarium still stands in Franeker today, now a museum in the old merchant's house. The mechanism that Eisinga built with his own hands more than 250 years ago continues to work, showing visitors the same paths of the planets that calmed the fears of an entire province. It stands as a reminder that sometimes the best answer to fear is knowledge, and that a single person with skill and patience can create something that endures for centuries.
Published August 24, 2026 · Frisian News