Originally published in Primum Mobile, vol 1, issue 1, September 2004.
Once Upon a Time . . .
In Which it is Decided that there is Truth,
and How it Benefits a Man to Seek that Truth
Once upon a time, men believed that the Earth was the center of the universe. They believed that several spheres circled the Earth, each containing a heavenly body, whether it be the Sun, Moon, or planets. Beyond that were the stars, and then there was a tenth circle, called the Primum Mobile, which caused the other nine spheres to spin. And then in some versions, the Primum Mobile itself was moved by its own love of God.
This vision of the universe, called the Ptolemaic System, is radically different from the modern one, and not simply because the Earth is at its center. After all, if we simply switch the positions of the Earth and the Sun, most of the other spheres fall into place quite nicely. The Moon is the first sphere, so we would need to attach that to the earth as we are moving that one out, but the planets are all in the right order (the planets past Saturn were not known then, so they do not even appear on the chart), so very little there needs adjusting. Except for the one detail about the Earth being at the center, the order looks pretty familiar.
So what else differs? Primarily, the Primum Mobile. Continue reading