Astronomical Images : The motion of planets 'pushed' by the Sun's immaterial species

Johannes Kepler

Astronomical Images

<p style='text-align: justify;'>Johannes Kepler's <i>Epitome astronomiae copernicanae</i> was published in three successive parts from 1617 to 1621. Intended as a new astronomical textbook for students, the <i>Epitome</i> covered much of the material traditionally associated with the <i>Theoricae planetarum</i> and works on spherical astronomy. Despite its title, the <i>Epitome</i> does not draw its information directly from Copernicus' <i>De revolutionibus</i> but is an original synthesis, mainly based on Kepler's own earlier works. It thus presents a comprehensive survey of Kepler's new astronomy. The text is illustrated by an abundance of images, with some figures printed multiple times. Kepler explained planetary motion according to 'solar magnetism', which was detected by magnetic fibres within the planetary body. This image demonstrates why the movement of planets, as driven by the light of the Sun, is not always the same but varies with distance. The diagram shows that as the distance of the planet from the Sun increases, the density of light decreases, thus affecting planetary motion.</p>