The scientific advance famously attributed to Galileo is the improvement of the telescope and the subsequent astronomical observations he made with it. Galileo's enhancements allowed him to observe celestial bodies in unprecedented detail, leading to significant discoveries, including the moons of Jupiter, the phases of Venus, and detailed observations of the sun and moon’s surface. His findings provided strong support for the Copernican heliocentric model of the solar system, challenging the long-held geocentric view and contributing to the scientific revolution that changed our understanding of the universe.