The ‘cosmographic’ celebration of the Medici dynasty found renewed vigor in the astronomical discoveries of Galileo (1564-1642). The Pisan scientist dedicated the four satellites discovered orbiting around Jupiter to his patrons, naming them the Medicea Sidera (Medicean stars). In keeping with a later suggestion made by the French astronomer Nicolas-Claude Fabri de Peiresc (1580-1637), the four celestial bodies were to assume the more precise names of "Cosmus mayor", "Franciscus", "Ferdinandus" and "Cosmus minor". The "Stanzino" was enriched with new Galilean instruments, such as the telescope and the geometric and military compass that Galileo had dedicated in 1606 to the young Prince Cosimo de’ Medici (1590-1621). The new astronomical discoveries also seemed to offer a solution to the crucial problem of calculating longitude, which would have confirmed the Medici’s political and military prestige still further. Testifying to the commitment shown again by Cosimo II to strengthen the Medicean fleet are a substantial group of nautical instruments left to the grand-ducal collection by the English Admiral Sir Robert Dudley (1573-1649), who was also the author of an important treatise on the science of navigation dedicated to Ferdinando II (1610-1670).