Supposedly, many who bought Stephen Hawking's book A Brief History of Time didn't understand it. But times change I think children reading the books of Lucy and Stephen Hawking will get it, as will any adults who sneak a peek. There are three in the series.
In the first book, the hero George has gone from a quiet life to trying to rescue his next door neighbor from a black hole. It's a lively illustrated story, includes beautiful color images of the universe, and there's an explanation of what a black hole is from a man who knows. George's adventures continue in George's Cosmic Treasure Hunt where the theme is the search for planets around other stars. George and the Big Bang, which is my favorite, sees George and Annie in a desperate race to save Annie's father and the Large Hadron Collider.
Someone else who encounters a black hole is Brian Greene's futuristic Icarus. The wings of wood and wax of this Icarus at the Edge of Time are a little spacecraft in which he flies too close to a black hole. There he finds that he should have paid more attention to Einstein. It would probably appeal to age range 7-11.
Russell Stannard, formerly a professor of physics, discovered that children's minds were open to some of the hard bits of modern physics. So he set out to write them into stories. The first book was The Space and Time of Uncle Albert, in which the adventures of Albert and his niece illuminate special relativity. It's great fun. There are also two further books in the Uncle Albert series which I haven't reviewed. They are Black Holes and Uncle Albert and Uncle Albert and the Quantum Quest.
James Lu Dunbar has two quirky volumes in The Universe Verse – in rhyme and graphical form. Bang! is in black and white, telling the story of the Big Bang and the beginning of the universe. Not to be confused with Bang! The Complete History of the Universe by Patrick Moore, astrophysicist and rock legend Brian May, and Chris Lintott - this isn't specifically for young people, but would be an accessible book for teens as well as adults.
For a straightforward informative book on astronomy for readers 8-14, Ian Ridpath's Exploring Stars and Planets is still the best. Illustrated with up-to-date images, it's the story of the Solar System, but with glimpses into galaxies, exploding stars and the history of the universe. For those in the UK, northern Europe and Canada, there is also the Philip's Astronomy Starter Pack that includes the book, a poster and a glow-in-the-dark planisphere. (The planisphere is for higher latitudes than most of the USA.)
A good Christmas stocking filler might be an entertaining overview of astronomy small enough to put in your pocket. Not only the Big Bang, black holes, exploding stars, visiting Mars and all the rest of the cosmos, but plenty of laughs along the way from Daniel Hudon's Bluffer's Guide to the Cosmos.
Mary Roach gives the lowdown on the not-so-glamorous aspects of space travel in Packing for Mars. She has an inquisitive mind, is a tireless researcher and a good writer with a wonderful sense of humor.
Another well-known writer is Dava Sobel and I found her book Galileo's Daughter a fascinating and moving insight into to the life of Galileo and the time in which he lived. I would also recommend Sobel's Longitude. I haven't reviewed it, but thoroughly enjoyed it. It's a splendid account of the attempts to solve the problem of determining longitude at sea. She chronicles John Harrison's obsessive work to perfect a marine timepiece that could be used at sea. (Harrison's chronometers are on display at the Royal Observatory in Greenwich, England.)
Full of boyish enthusiasm, physics professor Brian Cox has been a big hit on British television. There are books associated with the two series Wonders of the Solar System and Wonders of the Universe. Both are full of wonderful pictures. If I review the books, I will point out that the book on the Solar System has a dismayingly large number of not-very-wonderful typos and mistakes.
And for anyone seriously interested in astronomy, the most up-to-date and comprehensive of the astronomical dictionaries available is Ian Ridpath's Oxford Dictionary of Astronomy. I found it invaluable when I was studying astronomy - and still do. Be sure to get the latest edition (2012).
Here are all the books reviewed on this site.