Back to Article List Astro News Bytes: Downsizing the Andromeda Galaxy Astronomers used to believe that the Andromeda Galaxy, our nearest galactic neighbor, was three times the size of the Milky Way. Not anymore. By Astronomy Staff | Published: March 6, 2018 | Last updated on May 18, 2023 You can get the whole story in News: Just how big is the Andromeda galaxy?