Planets: Ours And Others - From Earth To Exoplanets

by Thérèse Encrenaz

What is a planet? The answer may seem obvious; still, the definition of a planet has continuously evolved over the centuries, and their number has changed following successive discoveries. In 2006, the decision endorsed by the International Astronomical Union to remove Pluto from the list of planets has well illustrated the difficulty associated with their definition. The recent discovery of hundreds of exoplanets around nearby stars of our Galaxy opens a new and spectacular dimension to astrophysics. We presently know very little about the physical nature of exoplanets. In contrast, our knowledge on solar system planets has made huge progress over the past decades, thanks, especially, to space planetary exploration. The purpose of this book is first to characterize what planets are, in their global properties and in their diversity. Then, this knowledge is used to try to imagine the physical nature of exoplanets, starting from the few parameters we know about them. Throughout, we keep in mind the ultimate question of the search for possible extraterrestrial Could life exist or have existed in the solar system and beyond? Thérèse Encrenaz is Emeritus Senior Scientist at the Centre National de la Recherche Scientifique. She works at the Observatoire de Paris, at the Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique (Lesia). She is a specialist of the study of planetary atmospheres, and has been involved in several space missions.

206 pages, Paperback

First published February 9, 2014

About the author

Dr. Thérèse Encrenaz is the co-author of Life Beyond Earth. She is is Emeritus Director of research at CNRS and an astrophysicist at LESIA, Paris Observatory.

Reviews

[Stephen Case · Rating 4 out of 5]

The art of an insightful, timely, and scientifically rigorous overview is a difficult one. This is compounded when the subjects are as broad as planets and stars, respectively. Fortunately for the educated non-specialists, there two slender volumes (this one and Birth, Evolution, and Death of Stars by James Lequeux) succeed where many astronomy texts fail: they provide a comprehensive, up-to-date survey of two fields with enough breadth to be useful and accessible to the astronomy educator while retaining enough technical grit for those desiring more depth.

The first volume (Planets), by an atmospheric planetologist at the Paris Observatory, frames the current state of exoplanetary research and the search for life in the context of comparative planetology, starting with Earth and moving through our planetary system.

Beginning with a brief introduction to observing and exploring planets (including exoplanetary detection), Encrenaz moves into a description of theories of planetary formation and then on to the bulk of the book, treating the physical properties of planets. Using Earth as test case and exploring things like geological activity and the water cycle, she provides in-depth comparison of the atmospheres, compositions, and internal structures of the planets of our solar system, touching briefly on some outer-system moons as well.

All of this sets the stage for the final third of the book, a look at exoplanetary systems-- their discovery, their properties, and a quick overview of the status of the search for life in the cosmos. The chapters here remind that this is not a book on exoplanets exclusively: rather, it's a survey of what we know about planets, which any more must include a detailed exposition of the ways other planetary systems are informing this knowledge.

In some respects, this is more helpful than a book on exoplanets alone, allowing an understanding of our own planetary context in light of these new discoveries.