The History of Cosmology - Andromeda Nebula

Davies: 1912 marked the true birth of modern cosmology, but there was no fanfare. It took several years and many more observations before Slipper's discovery gained prominence. In 1924, Hubble used the big 100 inch telescope at Mount Wilson in California to measure the distance to the Andromeda Nebula by managing to detect individual stars. And in doing so proved that Andromeda is in fact another entire galaxy like the Milky Way end quote. Davies goes on to say. You would notice every galaxy moving away from you, because the entire universe is expanding.