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. It is considerably more inclusive than either the McGraw-Hill Encyclopedia of Astronomy (LJ 4/15/93) or The Encyclopedia of Astronomy & Astrophysics (Van Nostrand Reinhold: Wiley, 1992). Suitable for scientists, students, and amateur astronomers, this work is recommended for academic libraries.