What was the crucial technological tool that transformed the Milky Way from a philosophical problem into an observable, physical one?

Answer

The development and refinement of the refracting telescope

The turning point arrived with the improvement of the refracting telescope, which allowed Galileo to multiply his visual view exponentially, moving the debate from purely philosophical speculation to empirical observation.

What was the crucial technological tool that transformed the Milky Way from a philosophical problem into an observable, physical one?
HistoryGalileoastronomytelescopeMilky Way