Grandmaster Science Fiction author Isaac Asimov wrote a number of non-fiction books on space, as well as a non-fiction column in several pulp digests.. Because he wrote juvenile fiction, for the most part, his non-fiction is plain and simple and easy to understand and it was only a matter of time before books fell into the public domain and could be picked up and repackaged for the juvenile audience.

These are two: collections of essays with added on illustrations and diagrams to further explain the concepts that are being discussed. Suitable for 3rd grade and up.