i am expecting that my small tribe of mathematical dandies will soon appear to correct me a bit. however, as far as i understand it, this is a bit of geometrical foppery by johannes kepler which was involved in his explaining the laws that control planetary orbits. this mostly occurred because google's image search isn't providing as many good drawings of pre-copernican song of the spheres heavenly machinery as it once did. i'm conceptually in the middle of the renaissance just now.