Acceleration: Galileo conducted experiments with falling objects and determined that the acceleration of a falling object is constant, regardless of its weight or shape.
This discovery provided evidence for the heliocentric model of the solar system, in which the planets revolve around the sun.
Galileo discovered four of Jupiter's largest moons - Io, Europa, Ganymede, and Callisto. This was the first time that moons were discovered orbiting a planet other than Earth
Galileo's experiments with inclined planes and rolling balls led him to develop the law of inertia
His observations of sunspots helped to disprove the idea that the sun was a perfect, unchanging celestial body, and they provided evidence for the Copernican model of the solar system.