For five decades after its discovery in 1930, the planet Pluto remained an enigma. However, several events during the last two decades have helped to lift the veil of mystery surrounding the ninth planet. The discovery of its satellite, Charon, in 1978 permitted occultation observations that allowed scientists to determine the size of both bodies. Astronomers also detected the presence of an atmosphere, and the Hubble Space Telescope provided views in unprecedented detail. In addition to these two fortuitous events, advances in telescopic instrumentation and computational methods led to exciting observational and theoretical discoveries. This new Space Sciences Series volume focuses on the scientific issues associated with Pluto and Charon. Fifty collaborating authors here review the latest research on the Pluto-Charon binary, from bulk properties, surfaces and interiors to atmospheric structure, composition, and dynamics. They also provide historical perspectives on Pluto-Charon research and discuss the population of the trans-Neptunian region and the origin of the Pluto-Charon binary. Also included are prefatory remarks by Pluto's and Charon's discoverers, Clyde Tombaugh and James Christy. This volume offers the most comprehensive available compendium of research work for understanding these far off members of our solar system, just at a time following dramatic developments in our knowledge but before that knowledge can be advanced by spacecraft missions.

Once perceived as distant, cold, dark, and seemingly unknowable, Pluto had long been marked as the farthest and most unreachable frontier for solar system exploration. After Voyager accomplished its final planetary reconnaissance at Neptune in 1989, Pluto and its cohort in the Kuiper Belt beckoned as the missing puzzle piece for completing the first reconnaissance of our solar system. In the decades following Voyager, a mission to the Pluto system was not only imagined but also achieved, culminating with the historic 2015 flyby by the New Horizons spacecraft. Pluto and its satellite system (“the Pluto system”), including its largest moon, Charon, have been revealed to be worlds of enormous complexity that fantastically exceed preconceptions.

The Pluto System After New Horizons seeks to become the benchmark for synthesizing our understanding of the Pluto system. The volume’s lead editor is S. Alan Stern, who also serves as NASA’s New Horizons Principal Investigator; co-editors Richard P. Binzel, William M. Grundy, Jeffrey M. Moore, and Leslie A. Young are all co-investigators on New Horizons. Leading researchers from around the globe have spent the last five years assimilating Pluto system flyby data returned from New Horizons. The chapters in this volume form an enduring foundation for ongoing study and understanding of the Pluto system. The volume also advances insights into the nature of dwarf planets and Kuiper Belt objects, providing a cornerstone for planning new missions that may return to the Pluto system and explore others of the myriad important worlds beyond Neptune.