How an ancient collision with another galaxy transformed the Milky Way

The Hubble Space Telescope has discovered evidence that our galaxy experienced a significant collision and merger with a dwarf galaxy 11.8 billion years ago.Mergers between galaxies are one of the main ways in which galaxies can grow. However, while we can witness mergers taking place in other galaxies, figuring out our Milky Way galaxy's history requires painstaking detective work. Even now,the story is only partly known."Our home is the Milky Way galaxy, but we do not know how our house was bu