History of astronomy
A significant astronomical advance of the 18th century was the realization by Thomas Wright (1711–1786) that the "fixed stars" were not scattered at random, but concentrated in what we now call the "galactic plane", our view of the Milky Way. What is even more remarkable is his idea that very faint nebulae, in which "no one star... can possibly be distinguished" might be extremely distant groups of the same kind.p83/4