Galilean Telescope

Timeline

1. 1609Venice · VenetoAfter learning of the Dutch 'far-seeing device', Galileo combined a convex lens as objective with a concave lens as eyepiece in the Padua–Venice area, raising magnification to about twentyfold and forming a refracting telescope prototype usable for astronomical observation.
2. 1610Padua · VenetoGalileo observed lunar craters, Jupiter's four moons, and the phases of Venus, publishing Sidereus Nuncius in 1610, using the telescope to empirically challenge the geocentric view of the cosmos and marking a key turning point in modern observational astronomy.
3. 1611–1620Europe · EuropeIn the 1610s, Galileo's telescope design was widely imitated across Europe; scholars in Rome, Paris, London, and elsewhere used similar instruments to observe sunspots, Saturn's rings, and other phenomena, making the telescope a standard research tool of the Scientific Revolution.