Galilean moons
Galileo called his discovery the Cosmica Sidera ('Cosimo's stars'), in honour of Cosimo II de' Medici (1590–1621), grand-duke of Tuscany, whose patronage he wanted. At the grand-duke's suggestion, Galileo changed the name to Medicea Sidera ('the Medici stars'), honouring all four Medici brothers (Cosimo, Francesco, Carlo, and Lorenzo). The discovery was announced in the Sidereus Nuncius ('Starry Messenger'), published in Venice in March 1610, less than two months after the first observations.