Alan Longstaff originally trained as a biochemist, and after working as a research scientist at the Universities of Rome and Aberdeen, taught for 18 years at the University of Hertfordshire. He jumped ship in 1998, becoming a University student once again, to study astronomy and geology. Now he divides his time between teaching and writing. A Fellow of the Royal Astronomical Society, Alan is an Associate Lecturer in Earth Sciences at the Open University, with research interests in astrobiology. He teaches astronomy at the Royal Observatory Greenwich and Waldegrave Science School for Girls and lectures widely to Astronomical and Geological Societies. As a freelance science writer specialising in medical sciences and astronomy, Alan has written and co-authored several textbooks; he writes for Astronomy, Astronomy Now, Popular Astronomy and similar publications.