Johann Georg Nestfell. Hesse, Germany. 1753.
The astronomical clock and orrery is a miracle of precision engineering, which combines ultimate craftsmanship with the state of knowledge in astronomy in the first half of the 18th century.
The astronomical clock and orrery was made in 1753 by Hessian craftsman cabinetmaker and amateur astronomer Johann Georg Nestfell for Emperor Franz I Stephan of Lorraine. “I spent many sleepless nights in observing the movement of the heavens for this” is how in 1761 he remembered the preparatory work.
His masterpiece shows the orbits of planets and moons around the Sun. The known ones at that time were Mercury, Venus, the Earth, the Moon, Mars, Jupiter with four moons, and Saturn with five moons. In addition, the clock showed the calendar, the Earth’s movement through the Zodiac, terminators, seasons, geocentric movements of Mercury and the time. The wooden base conceals the weights and pendulum of the eight-day clock. The clock itself and the gears and tracks for the planetary orbits are located in the upper part, which is made of glass and brass. The plans of the Earth’s orbit and the signs of the Zodiac are engraved in the glass case.
Before being exhibited in the NHM, the clock “strayed” from the Court Library to the imperial Physics Cabinet, then to the Animal Cabinet, from there to the Court Astronomical Cabinet, and even to the Museum of Fine Arts.
The astronomical clock and orrery was used to visualize and popularize the Copernican worldview, better known as the heliocentric system, in which all the planets, including the Earth, move around the Sun. What was then an incredible advance on the geocentric system is largely irrelevant in modern cosmology. Today, scientists believe that no point in the universe is superior to any other location – including the Sun.