When I was a kid in the 50s, I remember studying astronomy in 3rd grade (age about 8). We learned about the solar system, constellations, the Milky Way, Andromeda, and i think the Magellanic Clouds. My mother, born in 1913, remembered studying the solar system and the Milky Way, and that’s it.
So I’m wondering: when did scientists first realize that the Milky Way was not the only galaxy? Was there a specific telescope that was the first one strong enough to show that Andromeda wasn’t just another star? And was this a totally “WTF?” discovery, or had scientists already suspected it to be the case?
Hubble proved it in 1925, but the idea had been around a couple hundred years before him, just waiting for technology to become good enough to prove it.
Busy, dont have time to check references…but off the top of my head “we” knew what galaxies were sometime between the 20’s and ww2.
I am not sure whether it was a eureka moment, or a slow “ahhhhhhh” kind of revelation that took years to confirm and accept.
Do an internet search for “hubble” (the astronomer, not the the telescope) and “galaxies”…that should give you a good starting point
I’ve always thought “man, THATS when the universe got BIG”
As a thought experiment, ponder this. You look at the sky. There is the sun, big and bright. You have some idea of how far way it is (pretty damn far) Then there are all these stars. Hmmm, they must be like fireflys or sumptin. Then, one day, you figure out stars are just like the sun. Holy crap, just HOW far away do those suckers have to be for them to look like that?
Same thing with the galaxy revelation, only unbelievably bigger!
Actually Andromeda was known not to be a star. In 1781 Charles Messier published his catalog of nebulas, see http://www.delphes.net/messier/xtra/history/mcathist.html. Andromeda was M31. That and the galaxy in the triangle (M33) were the only naked eye visible ones, the latter only barely, but telescopically, they were all diffuse “clouds”. I don’t know that Messier had any idea what they were and most were either large hydrogen clouds or globular clusters in our galaxy, but at least those two as well as the Magellanic clouds were galaxies. The latter were two small satelite galaxies to the Milky Way.
They weren’t all diffuse clouds. Some of them were known by Messier to be star clusters, one obvious example being M45 (the Pleiades), which is also naked-eye visible of course.
The Andromeda Galaxy looks like, and for a long time was considered to be, a nebula–that is, a diffuse gas cloud. It was even called the Andromeda Nebula.
In the late Nineteenth Century, astronomers began taking spectra, and discovered the spectrum looked more like that of a star or star cluster. This led to a period of confusion during which no one was sure what it was. Hubble finally settled the matter by proving that it was in fact a very large and very distant star cluster, so large and distant that it was comparable to the Milky Way and would henceforth be described as a “galaxy”.
