If I had known this book was so easy to read, I would've read it sooner. A 747 full of students is hijacked by a giant spaceship and whisked off to Charon the moon of Pluto. The students and their teacher and the pilots are to be trained to take over the operation of the planet which is really hollow and a giant terrarium with dinosaurs rescued from Earth. It was a fun read and I finished it in about a week.