What mistaken belief about the universe persisted for some time after Galileo resolved the Milky Way into individual stars?

That the collection of stars forming the Milky Way constituted the entirety of the universe.

Galileo's 1610 observation represented a significant leap, transforming the Milky Way from an abstract feature into a physical congregation of stars. However, this resolution did not immediately lead to the modern understanding of the vastness of the cosmos. A common misconception that endured after Galileo's work was the belief that this newly understood collection of countless stars *was* the complete universe. It took subsequent astronomical advancements, notably the work of Edwin Hubble decades later, to confirm that these stellar clouds were themselves separate entities existing outside the boundaries of our own Milky Way.