The Eisinga Planetarium occupies the front room of a small canal-side house in central Franeker and is the oldest functioning planetarium in the world — built by the wool-comber Eise Eisinga between 1774 and 1781, and listed by UNESCO as a Memory of the World object. The mechanism, hand-cut from oak and brass, drives painted wooden discs that map the orbits of Mercury, Venus, Earth, Mars, Jupiter and Saturn onto the blue-painted ceiling of his living room, to scale and at real speed.
The accompanying museum explains how Eisinga did it without any formal education and how the planetarium has been kept running. The volunteers who run the place are knowledgeable and obviously proud. Allow at least an hour and ideally join one of the guided tours, where the workings in the attic are shown.