Planetariums

A planetarium is a device for artificially depicting the night sky, showing the relative positions and motions of the sun, moon, and planets. Modern planetariums are theaters, usually dome shaped, that employ elaborate equipment, including projector systems and lasers, for educating and entertaining the public about astronomy and for training nautical and military personnel in celestial navigation.

The lineage of the planetarium can be traced back to ancient Greece. An ancient mechanical calculator used to accurately determine astronomical positions was found in 1900 by sponge divers in what is now referred to as the “Antikythera wreck,” off the Greek island of the same name (located between Kythera and Crete) and has been dated to about 150–100 BCE. This technology was extraordinarily complex for the time, and it has no known precursor and no successor or equivalent until the 18th century CE. This movement, or one similar, with its high level of sophistication for that and most other eras, is widely believed to have been used in Archimedes' construction of a primitive equivalent to the modern planetarium. Rather than providing public entertainment or instruction to navigators in training, the creation of Archimedes was used to predict the movements of the sun, moon, and planets as known at that time and also to approximate their relation to each other at various phases and points in time.

Giovanni Campano, more readily identified as Johannes Campanus, was an Italian astrologer, mathematician, and astronomer of the 13th century. In his Theorica Flanetarum, Campano describes, and, more importantly, provides direction on how to assemble, a planetarium incorporating the astronomical knowledge at that time. Given the instructions left on how to build this piece, it can be stated that there is a very high correlation between the “planetarium” of Campano and the orrery of today. (The orrery is so named for the Earl of Orrery; Orrery is a location within Ireland, and an 18th-century Earl of Orrery had one constructed.) An orrery is a three-dimensional mechanical device that depicts the relative positions and motions of the planets and moons in the solar system, as well as their relation to each other, [Page 998]as based upon the presumption of Copernican heliocentrism. These pieces usually owe their movement to a large clockwork mechanism with a sphere (representing the sun) at its core and with a distinct and specific representation of a particular planet at the end of each of its arms. Given the small size of orreries as constructed by Campano and his predecessors, it appears that these devices were mostly used for personal curiosity, knowledge, and recreation, as they were not large enough to be of any true service to a crowd. One obvious limitation of this form of representation is its complete inability to replicate or depict the backdrop of stars and constellations.

An orrery or planetarium designed by George Adams showing the relative positions of the planets in relation to the sun (1799)

Source: Library of Congress, Prints & Photographs Division.

Early 19th-century England provided the backdrop for Adam Walker and his Eidouranion, the name given his very large orrery, approximately 20 to 25 feet in height, with a proportionate width. Walker's Eidouranion provides the first documented usage of an orrery for either educational or entertainment purposes, with his lecture incorporating both facets into a simulated presentation on the heavens. While not extremely precise in its representation, this show provided the audience an opportunity to encounter elements of time beyond an immediate number, day, and date. In relaying the parallels of heavenly occurrences such as a lunar phase, or planetary alignment, with definite cycles and events (e.g., seasonal change resulting from the earth's positioning and alignment in relation to the sun), Walker can be seen as one of many to have helped establish the depth and permanence of events of this world by incorporating the heavens as support. As Walker's popularity, and presumably wealth, began to grow, others such as William Kitchener and his Ouranologia began to take their rather inaccurate orreries on the road, forgoing scientific display for sensationalism and the awe of large crowds.

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