The standard theory of planet formation is based on our solar system. But does this view require revision based on the existence of misplaced giant planets-hot Jupiters circling close to their parent stars? Compare competing theories that try to resolve this conflict..

Our earliest written records of the Celts come from Italy, Greece, and Spain, dating as far back as the 6th century B.C. Although scholarly theories about the Celts' migration throughout Europe conflict, the foundation of our understanding of their origins is laid bare here, peppered with several curious historic anecdotes.