This authoritative reference volume features more than 2,200 terms and concepts covering a wide array of topics in astronomy and astronautics. This in-depth overview of important terms and concepts in the fields of astronomy and astronautics is designed to be an authoritative and easy-to-use reference book. With thousands of entries arranged alphabetically, it provides ready answers for students of space science as well as the curious reader. From "Aberration of Light" and "Abnormal Stars" to "Zodiacal Light" and "Zone Time", this comprehensive volume provides a wealth of fascinating information.