The general conclusion to be derived from the above results seems to be that the sun is a member of a cluster or stars, possibly distributed in the form of a ring, and that outside this ring, at a much greater distance from us than the stars of the solar cluster, lies a considerably richer ring-shaped cluster, the light of which, reduced to nebulosity by immensity of distance, produces the Milky Way gleam of our midnight skies.
ASTRONOMY by Agnes M. Clerke, The Concise Knowledge Library, 1898.
Mind blown!
William Herschel determined the approximate shape and rough size of the Milky Way in 1781.
In 1920, the famous Shapely-Curtis debate took place, with Shapely arguing that Herschel’s Milky Way was the universe, and spiral nebulas like Andromeda were just clusters within it. Curtis argued that each of spiral nebulas was an “island universe” unto itself.
http://en.wikipedia.org/wiki/Great_Debate_%28astronomy%29
Edwin Hubble settled the debate in 1924 when he observed a Cepheid variable in the Andromeda Galaxy, using the 100 inch Hooker Telescope and was able to apply Henrietta Swan Leavitt’s law to show that Andromeda was about one million light years from the sun, decisively confirming Curtis \’s
position.