Tycho Brahe - The Tychonic Model - Scientific Revolution - Dr Robert A. Hatch
KEPLER'S   FIVE   REGULAR   SOLIDS
POST-COPERNICAN MODELS & VARIATIONS
Dr Robert A. Hatch - University of Florida
   
By most accounts Johannes Kepler was a brilliant astronomer and mathematician.  He is remembered, in particular, for his three laws of planetary motion, which continue to grace the pages of modern survey texts in astronomy.  For all that, Kepler was also something of a mystic and freethinker.  Among his ideas not found in modern textbooks is the belief that the Five Regular Solids (three-dimensional geometrical objects with identical sides, for example a cube) account for the five intervals between the six known planets.  The illustration above shows how the five solids were nested one within the other to account for the number and the distances of the planets from the Sun.  The illustration below provides a similar description detailing the place of each of the Five Regular Solids.


 
 
As may be clear from the above illustration, Kepler maintained that the Five Regular Solids (specifically, the octahedron, icosehedron, dodecahedron, tetrahedron, and finally, the familiar cube) account for the intervals of space between the planets.  Surprisingly (or not) Kepler was able to make the ratios work with fair accuracy, though the failure with one of the planets seems to have been a motive for his accepting a position with Tycho Brahe, the Prince of Astronomers.  Kepler's theory of the Five Regular Solids first appeared his his Mysterium Cosmographicum (1596 - the Mystery of the Universe).  Evidence suggests Kepler believed in the efficacy of this theory all of his life, that is, it held equal weight with his so-called three laws of planetary motion. 

  
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