Kepler' ‘Distance Law’ - Myth not Reality

Abstract

I have carried out a selective reworking of Chapter 32 of Kepler's Astronomia Nova - which was the source of all his physical ideas - and have established that no foundation exists either there, or subsequently, for what is nowadays known as ‘Kepler's distance law‘. By contrast, I show that his innovative approach led him to consider the component of velocity which is precisely perpendicular to the Sun-planet line, and so to formulate motion taking place instantaneously in a circle round the Sun; this is exactly equivalent to the area law according to modern standards. Moreover, no other interpretation would have been compatible with Kepler's Aristotelian principles.