This four-volume set contains over 3000 articles covering a broad range of topics in astronomy and astrophysics, making it one of the largest reference sources available on the topic. Murdin (End of Fire: The Supernova in the Large Magellanic Cloud) and his editorial board have assembled more than 800 astronomers and astrophysicists, who produced both lengthy main articles tackling main themes in astronomy and briefer, unsigned entries. The 600-plus main articles range from 2500 to 5000 words and offer illustrations and bibliographic references, which sometimes include web sites. The shorter, unsigned articles are descriptions of space vehicles and missions, messier objects, observatories, definitions, and biographies. Most of the 2000 illustrations are black and white, with a few color-plate inserts grouped in the middle of each volume.