High-energy astrophysics has unveiled a Universe very different from that only known from optical observations. It has revealed many types of objects in which typical variability timescales are as short as years, months, days, and hours (in quasars, X-ray binaries, etc), and even down to milli-seconds in gamma ray bursts. The sources of energy that are encountered are only very seldom nuclear fusion, and most of the time gravitation, a paradox when one thinks that gravitation is, by many orders of magnitude, the weakest of the fundamental interactions. The understanding of these objects'...

G. Beutler's Methods of Celestial Mechanics is a coherent textbook for students as well as an excellent reference for practitioners. The first volume gives a thorough treatment of celestial mechanics and presents all the necessary mathematical details that a professional would need. The reader will appreciate the well-written chapters on numerical solution techniques for ordinary differential equations, as well as that on orbit determination. In the second volume applications to the rotation of earth and moon, to artificial earth satellites and to the planetary system are presented....

Written by a leading expert on comets, this textbook is divided into seven main elements with a view to allowing advanced students to appreciate the interconnections between the different elements. The author opens with a brief introductory segment on the motivation for studying comets and the overall scope of the book. The first chapter describes fundamental aspects most usually addressed by ground-based observation. The author then looks at the basic physical phenomena in four separate chapters addressing the nucleus, the emitted gas, the emitted dust, and the solar wind interaction....