Astronomical Images : Elements of geometry: the sphere

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 traditional diagram illustrates the generation of a sphere by the rotation of a semicircle, and is taken from the 'Wittenberg tradition' of illustrations of Sacrobosco's <i>De sphaera mundi</i>, that is, from a series of editions of the text printed in Wittenberg during the later sixteenth century. Kepler criticises this method (<i>modus mechanicus creandi Sphaerici</i>) for being convenient for beginners but unsuitable for genuine mathematical and philosophical purposes.</p>