Comet Observers in Florence in the Nineteenth Century

In the nineteenth century, thirteen comets were discovered, and many more were observed, from the city of Florence, Italy. One of the most remarkable discoveries was the great comet Donati (C/1858 L1). This chapter traces the history of the comet-hunters active in Florence (Jean-Louis Pons, Giovan Battista Donati, Wilhelm Tempel), highlighting the transition from classical studies of celestial mechanics to the emerging field of astrophysics. Furthermore, we focus on Donati’s involvement in the controversy about the comet 3/D Biela and the related spread of a hoax: the alleged impact of a comet with the Earth expected (or rather, invented) for 12 August 1872. We conclude that Florence was indeed “the headquarters of comets’’, as von Zach hoped for in 1825, but only at national level. The city that boasted the largest number of discoveries of comets in the nineteenth century is, in fact, Marseille.