How did Galileo Galilee find out that the earth is round?

Galileo Galilei did not directly discover that the Earth is round, as this concept was already established by earlier astronomers and philosophers. However, he provided crucial evidence supporting the heliocentric model by using a telescope to observe celestial bodies, such as the phases of Venus and the moons of Jupiter, demonstrating that not all celestial bodies orbit the Earth. His observations contributed to the understanding of the Earth's position in the solar system and its spherical shape, reinforcing the scientific consensus of his time.