The Copernican Orrery

Englische Version des Artikels "Das Kopernikus-Planetarium" 229.KOP

Cardboard kit for a mechanical planetary model showing the seasons, lunar phases, eclipses and the movements of the Earth, Moon, Venus and Mercury in approximate relation to their orbital periods.

Copernicus' discovery, Orrery's realisation

The mechanical planetariums of modern times are almost all based on the ideas of Nicolaus Copernicus (1473 - 1543), who assumed that the sun was the centre of the world. He taught that the earth makes three movements: it turns around itself once in 24 hours, travels around the sun in a circular path in a year and, with a third movement, turns its axis so that it always points in the same direction and not towards the sun.
At the beginning of the 18th century, the Earl of Orrery and other English noblemen commissioned mechanical crank-driven planetary models from clockmakers, which have since been called orreries in English usage.

Cranking around the sun

The Copernicus Planetarium shows the movements of the inner planets Mercury and Venus as well as the Moon and the Earth, rotating around their oblique axes, which are always aligned in the same way. One turn of the crank on the gear made of rubber belts and grooved wheels represents the course of a week. In the process, it produces six different simultaneous movements, which are in approximate proportion to the actual rotation times. Many celestial processes can be explained in this way from the Copernican (heliocentric) point of view, e.g. the wandering of the sun through the zodiac or the conjunctions of Mercury and Venus with each other and with the sun.
The sun with bright LED illumination shows in the dark room not only the change of the seasons, but also the emergence of the moon phases, the eclipses and the crescent phases of Venus.

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