Sky & Telescope - USA (2019-08)

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KEPLER ANNIVERSARY by F. Michael Witkoski

58 AUGUST 2019 • SKY & TELESCOPE

This year marks the

400th anniversary of

Kepler’s Third Law of

Planetary Motion.

Planets

Governing

the

POLYHEDRAL SEPARATION

Kepler’s model of the solar system

relied on Platonic solids — im-

mutable polyhedra nested inside a

series of spheres thought to carry

the planets.