* The phases of Venus: This was a groundbreaking discovery that strongly supported the heliocentric model of the solar system. Galileo observed that Venus goes through phases, just like the Moon. This was only possible if Venus was orbiting the Sun, not the Earth.
* The moons of Jupiter: Galileo discovered four moons orbiting Jupiter. This was a major blow to the geocentric model, which stated that everything in the universe revolved around Earth. The fact that Jupiter had its own system of moons orbiting it showed that not everything centered around Earth.
These discoveries, along with others, helped solidify Galileo's place as a key figure in the Scientific Revolution.
