Galilean Telescope

Timeline

1. 1608Middelburg · ZeelandDutch spectacle maker Hans Lippershey applied in 1608 to the States General of the Netherlands for a patent on the refracting telescope, a design combining one convex and one concave lens to produce a magnified image, initially at about 3x; news spread rapidly through Europe's scientific circles, and it became the prototype of the modern astronomical telescope.
2. 1609Padua · VenetoGalileo ground lenses independently in Padua, raising the telescope's magnification to about 8–20x, and in August 1609 demonstrated its military uses to the Venetian Senate. He then turned the lens skyward, observing mountains and craters on the Moon and confirming that celestial bodies were not the smooth, perfect spheres Aristotle had described, shaking the traditional worldview.
3. 1610Padua · VenetoOn January 7, 1610, Galileo discovered with his improved telescope four moons of Jupiter (later called the Galilean moons: Io through Callisto), proving that not all celestial bodies orbit the Earth and providing key observational evidence for heliocentrism. That March he published Sidereus Nuncius, shocking Europe's scientific circles and marking the formal beginning of the observational era of modern astronomy.