The Invisible Galaxies of Andromeda

There are moments where there are zero photons arriving from a distant galaxy. And that's why you just can't see them. You need to wait long enough or like point Hubble at it long enough to sort of integrate enough photons. Imagine just like having another galaxy out there for us to look at from the outside. It would change our whole concept of galaxies and what they are if we could have seen Andromeda.