He is editor of the "Oxford Dictionary of Astronomy" and Norton's Star Atlas, and author of observing guides such as "The Monthly Sky Guide" and the "Collins Stars and Planets Guide" (the latter two with charts by Wil Tirion, and both continuously in print for over 30 years). His other books include "Star Tales", about the origins and mythology of the constellations, and the children's book "Exploring Stars and Planets", now in its fifth edition. He is a contributor to the Dorling Kindersley encyclopedia "", and a former editor of the UK quarterly magazine "Popular Astronomy". He is also currently editor of "The Antiquarian Astronomer", the journal of the Society for the History of Astronomy.