mar 18, 1920 - Edwin Hubble: He was studying the Andromeda Nebula and noticed that it had stars that looks like stars from the Milky Way but much fainter. He came to the conclusion that the stars in the Andromeda Nebula were much farther from Earth. This gave evidence that the Andromeda Nebula was a different galaxy and that not all celestial objects were in the Milky Way.
Added to timeline:
Date:
mar 18, 1920
Now
~ 106 years ago