In 1614, the German astronomer Simon Mayr published his claim about the discovery of Jupiter’s satellites. In his treatise Mundus Jovialis, Mayr made his assertion in a convoluted but unequivocal manner, earning resentment from Galileo Galilei, who published his harsh protest in 1623 in Il Saggiatore. Though Galileo’s objections were fallacious in some respects, and though numerous scholars took to the field to prove Mayr’s claim, none ever really succeeded, and the historical evidence remains to Mayr’s (...) detriment. On the basis of such historical evidence, including comparisons between Mundus Jovialis and Mayr’s earlier works, Mayr’s independent discovery of the satellites can be ruled out. Indeed, it is very likely that he never observed them before 30 December 1610, nearly a year after Galileo. The lack of a corpus of Mayr’s observations and the inaccuracy of his tables are also puzzling. (shrink)