Alien Skies: A Travelogue of the Universe gives readers the opportunity to travel through the universe, visiting a series of celestial destinations carefully chosen to span the extraordinary limits of space and time that bound our amazing cosmos. The destinations in Alien Skies reveal the unusual skies seen from throughout the solar system, nearby stars, nebulae, and star clusters, and during a series of voyages exploring the structure and content of our home galaxy. The itinerary includes nearby 'normal' galaxies, exotic active galaxies, as well as galaxy groups, clusters and cosmic voids. The final destinations of the journey traverse space and time to view the evolution of galaxies and cosmic structure, and of the universe as a whole. Alien Skies provides a broad, factual overview of modern astronomy, while instilling interest and enthusiasm of how science reveals the wonders of our universe. This book can serve as the text for introductory courses aimed at non-science majors or as background for courses geared to astronomy and astrophysics majors. It is also suitable for advanced courses at the high school level. Mario Mateo holds a Ph.D. from the University of Washington and is currently a professor in the Department of Astronomy at the University of Michigan with over 20 years of experience teaching introductory astrophysics courses. He is an active observational astronomer who has published extensively in professional journals on such diverse topics as stellar evolution, cataclysmic variable stars, gravitational lensing, dwarf galaxies, blue stragglers, stellar streams in the Galactic halo, pulsating stars in extragalactic systems, black holes, and the dark matter phenomenon. He has led the construction of large-scale astronomical instruments for use at observatories in Arizona and Chile.