The Royal Eise Eisinga Planetarium is an 18th-century orrery located in the living room of a small, two-story house in Franeker, Friesland, Netherlands. Its moving model of the solar system was constructed between 1774 and 1781 by Eise Eisinga, a Frisian wool comber and amateur astronomer. Eisinga expected to finish the planetarium within six months, but it took him seven long years. He used a scale of 1: 1,000,000,000,000 (1 millimeter: 1 million kilometers) so that it would fit into his living room.
To create the gears for the model, 10,000 handmade nails were used. In addition to the basic orrery, there are displays of the phase of the moon and other astronomical phenomena. A pendulum clock and a series of intricate mechanical gears drive the planets at the precise rate they do in our solar system.
An orrery is a planetarium, a working model of the solar system. The “face” of the model looks down from the ceiling of what used to be his living room, with most of the mechanical works in the space above the roof. It is driven by a pendulum clock, which has nine weights, or “ponds”. The planets move automatically around the model in real time (a slight “re-setting” must be done by hand every four years to compensate for the February 29th of a leap year.) The planetarium includes a display for the current time and date. The plank that has the year numbers written on it has to be replaced every 22 years.
Eisinga’s planetarium was built to stop doomsday prophecies. It was designed to disprove a contemporary prophecy that certain planets were on a collision course and that the end of the world was, therefore, imminent. It could demonstrate that the planets were actually in conjunction, and there was no reason for panic. The Eisinga Planetarium received a lot of visitors when it opened. When King William I visited the planetarium in 1818, he was so impressed that he subsequently bought it for the Dutch state.
After Eisinga’s death in 1828, his family continued to run the planetarium until 1922. Today, the planetarium is still in full working order and is completely intact, in terms of both form and materials. Maintenance is still carried out and is now run by curators appointed by the city of Franeker.