2007-12-13 13:32:43 · 3 answers · asked by Day-Z 1 in Science & Mathematics ➔ Astronomy & Space
We have known about their existence for centuries, we just did not understand what they were. Up until the early 20th century, astronomers thought that the universe consisted of the Milky Way Galaxy, and the other galaxies that could be seen (e.g. M31) were nebulae like the dust and gas clouds that indeed are part of the Milky Way - like M42 in Orion. When we started getting photographs from modern scopes like the ones on Mt Palomar and Mt Wilson, they began to understand that the universe was a lot bigger than they originally thought. Folks like Sandage, Hubble and Humason made it clear that those fuzzy spirals are actually gigantic galaxies, separate "island universes" independent of the Milky Way. They also showed that the universe is expanding. None of this occurred without great controversy and scientific debate - but that's how science works.
2007-12-13 13:53:46 · answer #1 · answered by Larry454 7 · 1⤊ 0⤋
Hubble identified the first galaxy other than the milky way in the 1920's. But people had thought about them in the past, and thought that nebulae seen by the naked eye may be galaxies like the Milky Way.
2007-12-13 21:46:46 · answer #2 · answered by Joechicago 2 · 0⤊ 0⤋
other galaxies were just little blurry things and were considered nebula inside our Milky Way until Hubble showed using Cephid Variables that they were much too distant to be within our galaxy... that was early 1920s
2007-12-13 21:45:53 · answer #3 · answered by Faesson 7 · 1⤊ 0⤋