The ghosts of galaxies past.

  title={The ghosts of galaxies past.},
  author={R. Ibata and B. Gibson},
  journal={Scientific American},
  volume={296 4},
W hen you look up at the night sky, the stars that you see all reside in our own galaxy, the Milky Way. The nearest large galaxy to us, Andromeda, is more than two million lightyears away, a distance 20 times the size of the main disk of our galaxy. With the unaided eye, you cannot make out its stars individually; they blend together into a faint fuzz. As far as our galaxy is concerned, those stars might as well inhabit a separate universe. Conversely, it is natural to think of the stars in our… Expand