Astronomy is by nature an interdisciplinary activity: it involves mathematics, physics, chemistry and biology. Astronomers use (and often develop) the latest technology, the fastest computers and the most refined software.  In this book twenty-two leading scientists from nine countries talk about how astronomy interacts with these other sciences. They describe modern instruments used in astronomy and the relations between astronomy and technology, industry, politics and philosophy. They also discuss what it means to be an astronomer, the history of astronomy, and the place of astronomy in society today.   The book contains twenty chapters grouped in four parts: ASTRONOMY AND PHYSICS discusses the place of astronomy among various branches of (mostly high-energy) physics. ASTRONOMY IN SOCIETY describes not only the historical context of astronomy, but issues facing astronomers today, including funding, planning, worldwide collaboration and links with industry. THE TOOLS OF OBSERVATION AND THE PROFESSION OF ASTRONOMER discusses very small and very large telescopes, as well as mirror technology, the storage, organization and distribution of data, being an astronomer today, and the role played by planetaria in educating the general public. ASTRONOMY AT THE FRONTIERS OF KNOWLEDGE highlights the struggle of astronomy versus astrology, and the sciences of cosmology, planetology and astrobiology. This fascinating book will appeal to professionals in the fields of astronomy and physics, as well as space institutes, research agencies and the general public.