Gerald North graduated in physics and astronomy. He was a former teacher and lecturer in both subjects and a former Guest Observer at the Royal Greenwich Observatory, and is now a freelance astronomer and writer. He is a long-term member of the British Astronomical Association and has served in several senior posts in their lunar section. He has published widely over the years and is the author of this book's popular companion volume Observing the Moon: The Modern Astronomer's Guide, 2nd Edition (Cambridge University Press, 2007).