Besides, the discovery that moons orbit Jupiter, what other discovery made by Galileo Galilei, with an early telescope, proved that the Earth is not at the center of the Universe?

He made great advancements in developing a logical way to know more about the universe and celestial entities inside the space. And this theory is termed to be heliocentric in nature.

Explanation:

In early times most of the people believed that our planet Earth is the center of the universe or the solar system and rest of the celestial entities move around it in a given path, so, it confused the well known scientist named as Galileo Galilei. As, he observed the different dark patches or shadow like textures on the face of the Sun.While, it is more obvious to known that any object having multiple small shadows means that it is present inside such a region that all of the celestial entities move or orbit around it in a given way.So, he concluded that planet Earth itself move around the red Giant in a given way rather then being the center of the universe.