Astronomical Images : The motion of the Earth around the Sun explained according to the theory of magnetism

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. This image shows the motion of the Earth around the Sun, demonstrating that the axis of the Earth remains constant in its inclination to the ecliptic. It also illustrates the role of solar magnetism and the earthly magnetic fibres that detect it, according to Kepler's explanation for the motion of the Earth (the magnetic rays and fibres are represented by the hachure lines). The image is, however, rather crudely executed and thus the details are somewhat unclear.</p>