Napoleon: You have written this huge book on the system of the world without once mentioning the author of the universe. ~~ Laplace: Sire, I had no need of that hypothesis. ~ | LATER| Lagrange: Ah, but that is a fine hypothesis. It explains so many things.
Astronomers have discovered the largest known structure in the universe, a clump of active galactic cores that stretch 4 billion light-years from end to end. The structure is a light quasar group (LQG), a collection of extremely luminous Galactic Nuclei powered by supermassive central black holes.
Smaller satellite galaxies caught by a spiral galaxy are distorted into elongated structures consisting of stars, which are known as tidal streams, as shown in this artist's impression. The new survey has, for the first time, shown the presence of such tell-tale traces of spiral galaxies swallowing smaller satellites for galaxies more distant than our own “Local Group” of galaxies. Image: Jon Lomberg in collaboration with David Martinez-Delgado for the Stellar Tidal Stream Survey