Why build a planetarium?
Scientists assume the phenomena we see in the world around us are an orderly consequence of the interactions among the objects. Science is the process of building models of these interactions. In 1686 Isaac Newton published his Principia, providing a general conceptual model that made sense of the motions observed in our solar system. The various mechanical models that comprise the Botjes planetarium exhibit many of the straightforward and the subtle features of Newton's conceptual model as applied to our solar system. It serves as a real-time calculator, from which can be read the positions in the sky of the stars, moon, sun, and planets, and from which can be inferred the phases of the moon and the timing and nature of eclipses.
The power of this particular model is underscored by its durability: the planetarium is over 130 years old, and yet predicts movements as well as it did the day it was completed. That the device was intended for the long term is clear from the inclusion of the planet Uranus, discovered just 75 years before construction began. The motion of this planet is so gradual that it has completed just over one and a half revolutions since the planetarium was set in motion.
More specifically, planetariums have been constructed as an antidote to superstition. Eise Eisinga began building a planetarium in 1774, after an unusual conjunction of planets that spring led to fear about the impending doom of the earth (see descriptions at the Eisinga Museum websites, both official and unofficial). Wildrik Botjes may have been inspired by Eisinga, working less than a century later and only sixty miles away. The mechanical planetarium counters a fearful view of a random future with a reassuring view of an orderly process. The Botjes family held firm Christian convictions, and the scientific view of an orderly universe is consistent with the New Testament description of Christ as "upholding the Universe by his word of power." (Hebrews 1.3, RSV).
The tradition of planetarium building has been continued today by software writers. These planetariums replace the mechanical with the virtual, and their likelihood of lasting more than a century is slight. Nonetheless their power to compute past and future along with the present and their accessibility via the internet (for example at the Weather Underground) make them a worthy and valuable extension of the tradition.
|Botjes planetarium home page|
|Orbits of the planets|