feb 16, 1925 - American astronomer Edwin Hubble
Description:
proves conclusively that nebulae such as the Andromeda Nebula are much too distant to be part of the Milky Way and are in fact entire galaxies outside our own, thus settling the “Great Debate” about the nature of spiral nebulae and the size of the universe.Added to timeline:
Date:
feb 16, 1925
Now
~ 101 years ago