This book gives a comprehensive overview of the current observational and theoretical status in the field of the local and general interstellar medium. It contains contributions presented at the IAU Colloquium No. 166. Review articles and highlight talks will serve both as an introduction to the field for the undergraduate or the non-specialist and also give a summary of the most recent developments for the expert and researcher. These articles are supplemented by a representative number of original research papers. All contributions are fully refereed and have been edited with extensive care to provide a high-standard reference book. The scientific content spans a wide range from solar system measurements of dust grains to X-ray emission from distant galaxies.

ROSAT, the ROentgen SATellite launched in 1990, has revealed an entirely new aspect of the night sky - that of objects emitting X-rays rather than the rays of light visible to the human eye. This lavishly illustrated book is the first to describe one of the most remarkable instruments in modern astronomy. It offers fascinating images and engaging accounts of a wide range of Solar-System and deep space objects such as Comet Hyakutake, the Sun, the Moon, and objects outside the Milky Way.