Galileo galilei was the first scientist to perform experiments in order to test his ideas. He was also the first astronomer to systematically observe the skies with a telescope. Galileo made four key observations that challenged the widely accepted philosophical beliefs on which the geocentric model was based

Galileo four key observations are

1. Jupiter has orbiting moons.

2. The Sun has sunspots and rotates on its axis.

3. The Moon has mountains, valleys, and craters.

4. Venus goes through a full set of phases.

Explanation:

The above are Galileo's observations that went against the geocentric model and the general beliefs about the universe at the time.

His most critical observation was when he stated that planet Venus is different phases; this observation has a direct impact on the notion that objects orbit the Sun but not the Earth.

He went further to state his observations that the Sun and Moon had surface rough and imperfect surface. This observation disproved the idea that the moon and the Sun had perfect surfaces.

Galileo's observations of Jupiter's orbiting moons showed that there were other centers of motion in the universe.

c. newton's third law of motion