Unveiling the Mysteries of Cepheids and Hubble's Work

[SUDOnym]

hello

Can someone please clarify a point about Hubble's work?:

By using cepheids Hubble showed that the so called "nebulae" were too distant to be contained within our galaxy. My question is the following: is it only with the buidling of the 100-inch telescope that they were able to resolve the "nebulae" into individual stars and so then focus on the cepheids?
ie. before the 100-inch telescope, the other galaxies were too far away to resolve into individual stars which is why they were mistaken for nebulae.

And to drive the point home - Was there any instance before the use of the 100-inch that individual stars could be resolved in other galaxies?

 

[phyzguy]

I think you are correct. Before the Mt. Wilson 100 inch telescope, there was debate as to whether the "spiral nebulae" were so-called "island universes" (which we today call galaxies), or whether they were nebulae within our own galaxy. Hubble and Humason used the 100" to resolve Andromeda into stars and identify Cepheid variables within it, thereby measuring its distance. This showed that the spiral nebulae were in fact separate galaxies.