Astronomical Images : Tycho Brahe's faulty diagram

Johannes Kepler

Astronomical Images

<p style='text-align: justify;'>This woodcut reproduces a diagram first used by Tycho Brahe in his <i>De mundi aetherei recentioribus phaenomenis</i> (1588) as part of his argument to show that the comet of 1577 moved above the sphere of the Moon. This diagram was faulty and was criticized by other astronomers, including Orazio Grassi (1583-1654), Galileo Galilei (1564-1642) and Scipione Chiaramonti (1565-1652). Johannes Kepler wrote a defence of his erstwhile master and mentor's arguments in <i>Tychonis Brahe Dani Hyperaspistes, adversus Scipionis Claramontii ... Anti-Tychonem</i> ('Shieldbearer to Tycho Brahe the Dane, against the 'Anti-Tycho' by Scipio Chiaramonti'). In the appendix to this work Kepler acknowledges the faultiness of the diagram by calling it a <i>pseudographum</i>, that is 'misrepresentation', originally prepared for one demonstration and then 'tortured' to fit another. Kepler sought to partially excuse Tycho's diagram by explaining the original demonstration for which the diagram was valid.</p>