Appreciating the principles that underlie the physical world requires a keen understanding of astronomy and space exploration. Featuring more than 2000 entries, this reference combines relevant terms, facts, chronologies and tables into a single resource. Among the topics covered are: active galaxies; big bang theory; deep space network (DSN); international space station (ISS); luminosity; planet fall; and space transportation system (STS). The featured biographies include: Neil Armstrong; Friedrich W Bessel; Tycho Brahe; Giovanni Domenico Cassini; Nicholaus Copernicus; Edmond Halley; Stephen William Hawking; Christiaan Huygens; Carl Edward Sagan; Charles Joseph Messier; and Johannes Kepler. The tables, charts and diagrams include: absorption spectrum; Baker-Schmidt telescope; centrifugal force; equatorial axis; Hertzsprung-Russell (HR) diagram; Kepler's laws; magnetosphere; outer planets; Stefan-Boltzmann law; and X-ray astronomy.