
 Johannes Kepler  Facts, Info, and Encyclopedia article (Site not responding. Last check: 20071027) 
  The smallest orbit, that of Mercury, was the innermost sphere. 
  To emphasize his theory, Kepler envisaged an impressive model of the universe which shows a cube, inside a sphere, with a tetrahedron inscribed in it; another sphere inside it with a dodecahedron inscribed; a sphere with an icosahedron inscribed inside; and finally a sphere with an octahedron inscribed. 
  To his disappointment, Kepler's attempts to fix the orbits of the planets within a set of polyhedrons never worked out, but it is a testimony to his integrity as a scientist that when the evidence mounted against the cherished theory he worked so hard to prove, he abandoned it. 
 www.absoluteastronomy.com /encyclopedia/j/jo/johannes_kepler.htm (2331 words) 
