From the big bang to black holes.
This book needs no introduction. It was the first non-fiction book which I ever read in 1988. Everything up until that point was stories, and this book told a much bigger and real-life story, about our universe, and how it worked. It took me years to understand everything in it, but it was the book which unlocked the non-fiction world for me. Over twenty years later, it is still a best-seller.