Kepler's Explanation for Spacing of Planets

Conjecture
In the 16th century there were $6$ known planets.

It was also known that there were Five Platonic Solids.

reasoned that it was possible to fit the orbits of the planets into spheres such that:


 * $(1): \quad$ Between each sphere was a (real or imaginary) platonic solid
 * $(2): \quad$ The sphere of one planet was inscribed within the platonic solid between that and the next planet out
 * $(3): \quad$ The sphere of one planet was circumscribed around the platonic solid between that and the next planet in.

Thus:


 * Between the orbits of Mercury and Venus was an octahedron
 * Between the orbits of Venus and Earth was an icosahedron
 * Between the orbits of Earth and Mars was a dodecahedron
 * Between the orbits of Mars and Jupiter was a tetrahedron
 * Between the orbits of Jupiter and Saturn was a cube.