Written by Neil Armstrong; illustrated by Grahame Baker-Smith. Crown; $17.99; 48 pages. In 2006, NASA named Neil Armstrong an Ambassador Explorer, and presented him with a small fragment of a rock he’d brought back to Earth from the moon in 1969. During Armstrong’s acceptance speech he dubbed the fragment “Bok,” and described all the things Bok must have witnessed over billions of years. This charming book, adapted from that speech, combines Baker-Smith’s lush illustrations with a story sure to charm readers. The story starts with the celestial fender-bender that produced the moon, and continues with Bok—a piece of basalt that broke off from a larger rock—being hit by an asteroid, something that took him “about half a billion years to get over.” As he cycles between sleeping and gazing at the Earth, Bok endures as continents form on Earth, dinosaurs roam, and Neil Armstrong is born. He’s jostled from a nap as Armstrong throws him into a box “with some acquaintances he knew only slightly,” returning to Earth with the crew of Apollo 11. An appendix includes additional information about the moon, Earth, and Armstrong. Ages 4 to 8.