| Kepler's
theory of the solar magnet can be distinguished from his theory of species
Immateriata. Kepler'scelestial hypothesis also required a motion
perpendicular to the radius vector (the
species Immateriata). Following
Aristotle's principles of motion, that motion required a mover, Kepler
was oblidged to explain why the planets moved at all. Further, he
was obliged to explain why the planets did not follow perfect circular
paths. Hence, Kepler posited l) magnetic attractions and repulsions
between the sun and planets; and 2) the motion of the planets due to the
species
immateriata. Hence, Kepler held that the planets move naturally
in circular paths but are drawn from that perfect path by the Sun (a curious
bi-polar magnet). Kepler's celestial physics is an odd amalgam of Aristotellan
physics, Platonic Idealism, Gilbertian magnetic speculations, and sound
empirical investigation. |
