Astronomical discovery involves more than detecting something previously unseen. The reclassification of Pluto as a dwarf planet in 2006, and the controversy it generated, shows that discovery is a complex and ongoing process one comprising various stages of research, interpretation, and understanding. Ranging from Galileo's observation of Jupiter's satellites, Saturn's rings, and star clusters, to Herschel's nebulae and the modern discovery of quasars and pulsars, Steven J. Dick's comprehensive history identifies the concept of extended discovery as the engine of progress in astronomy. The...