Diamondblue - we've on our 3rd reading of Death By Black Hole with DS. It is his favorite although I have to say the vocabulary in it is quite challenging and there are times where I really wonder what he is getting out of it (he's 7.5). The George's Secret Key to the Universe series (Lucy & Stephen Hawking) and The Cosmic Menagerie have been the only thing that can compete (can you sense a theme.....). The George series is fantastic for younger kids, the Cosmic one has spectacular pictures (sort of a coffee table book but with a PhD providing content) and has shorter write ups about everything in the universe.