[PDF] Johannes Kepler - Nathalie Van de Wiele

Who was Johannes Kepler?

Johannes Kepler ( / ?k?pl?r /; German: [jo?han?s ?k?pl?, -n?s -] i; 27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, natural philosopher and writer on music.

Why did Kepler write de fundamentis?

In his bid to become imperial astronomer, Kepler wrote De Fundamentis (1601), whose full title can be translated as “On Giving Astrology Sounder Foundations”, as a short foreword to one of his yearly almanacs.

How does Kepler conceive a model with parallel magnetic fibers?

Kepler conceives of a model with parallel magnetic fibers which links the Sun with the planets in such a way that the rotation of the Sun causes the motion of the planets around it. The fibers are born in the planets parallel and perpendicular to the lines of apsides by a kind of “animal power”.

How does Kepler explain inclinatio ad quietem?

This phenomenon can be explained by referring to a property of matter, which for Kepler has an axiomatic character: the inclinatio ad quietem, that is, the tendency to rest (see especially AN, chap. 39; KGW 3, p. 256). As a consequence, the planets are moved around the Sun slower than they would be if the power of the Sun were at work alone.