New stars, old cosmologies in early modern Europe

The “New Star” of 1572 and later the comet of 1577 undermined the hegemonic notions concerning the immutability of the heavens and of the solidity of the celestial orbs and signaled a critical moment in the dissolution of the Aristotelian-Ptolemaic worldview. These dramatic events, associated with the herculean figure of Tycho Brahe, were extensively discussed in scholarly literature and received their due place in general surveys and textbooks concerned with the Scientific Revolution. The heroic episode of the 1570s overshadowed another “New Star” that appeared less than 30 years later and was thus much disregarded in the history of science. The collection of essays, here under review, is the culmination of an ongoing historiographical effort by Patrick Boner and several other historians of science to amend this picture and underscore the significance of the controversy over the appearance of a “New Star” in 1604, and especially the importance of Kepler’s treatise concerning this celestial event. The three decades that had elapsed since Tycho Brahe and Michael Maestlin observed the bright new light in the sky over northern Europe gave much time for mathematicians, star-gazers, and natural philosophers to assess the radical conclusions of Brahe. The appearance of another “New Star” in 1604 provided a suitable opportunity to review the implications of the new view of the heavens as mutable. In the discussions and controversies that followed the appearance of this new celestial body, Kepler stood out in understanding that novelties in heaven demand new modes of knowledge. It was an occasion to redraw the demarcating lines separating well-established astronomical inquiries and superstitious speculations. Further, it provided him with a fortunate opportunity to promote the heliocentric cause on both mathematical and philosophical grounds. The main difficulty Kepler faced regarding the appearance of a new celestial body was the clash between his belief that the same principles of generation and decay govern the realm above the moon just as they govern the world below it and the notion associated with this belief in the infinity of the world. If stars are born and die, then one may assume a plurality of worlds; according to the radical cosmologies of Epicurus and Giordano Bruno, such a plurality requires an infinite and homogenous space to contain it. Kepler abhorred the notion of an infinite universe that undermined his conviction in a well-ordered world with an identifiable center to determine questions of distance and direction. 1193712 JHA0010.1177/00218286231193712Journal for the History of AstronomyBook Reviews book-review2023