The Royal Eise Eisinga Planetarium is an 18th-century orrery in Franeker. It is currently a museum and open to the public. The orrery has been on the top 100 Dutch heritage sites list since 1990 and nominated as a UNESCO World Heritage Site candidate based on its long history as a working planetarium open to the public and its continued efforts to preserve its heritage.
The orrery was built from 1774 to 1781 by Eise Eisinga. 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 ceiling. It is driven by a pendulum clock, which has 9 weights or ponds. The planets move around the model in real time, automatically. 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.
The Eise Eisinga Planetarium is the oldest still working planetarium in the world. 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. The orrery was constructed to a scale of 1:1,000,000,000,000 (1 millimetre: 1 million kilometres).
References:House of the Blackheads (Melngalvju nams) is a building situated in the old town of Riga. The original building was erected during the first third of the 14th century for the Brotherhood of Blackheads, a guild for unmarried German merchants in Riga. Major works were done in the years 1580 and 1886, adding most of the ornaments.
The structure was bombed to a ruin by the Germans June 28, 1941 and the remains demolished by the Soviets in 1948. The current reconstruction was erected from 1995 to 1999. Today the House of Blackheads serves as a museum and sometimes concert hall.