Knight begins with our galaxy, playing up the ""mysterious"" ring around the center which is both moving and expanding outward (potentially dangerous to earth? astronomers aren't sure). He then ranges outward to other galaxies, which were first verified in 1925 by Edwin Hubble who also established the classification system described here, and to the groups and clusters and superclusters into which they fall. Finally, Knight skims over current theories of galactic evolution, recent findings and ideas about the ""violent processes"" taking place in their centers, and speculation about the future of the universe--all of which has been more fully investigated elsewhere, though without the galaxy orientation. A neat summary overall, without Asimov's patient detail or Branley's sense of shared inquiry.