Galaxies

Book excerpt: An eminently readable overview of the history and physics of galaxies. In Galaxies, Or Graur offers a brief and fascinating overview of the history, physics, and astrophysical uses of galaxies. Starting with the history of the last two thousand years of galaxy studies, Graur discusses the types of galaxies we observe and the physics that drive them; the myths and physical structure of the Milky Way; how galaxies were used to discover and study the mysterious phenomena of dark matter and dark energy; and how scientists think galaxies formed shortly after the Big Bang and evolved to their present forms. Tracing galaxy studies back thousands of years ago to their beginnings, Graur describes their origin in Ptolemy’s book Almagest, which was written in the first century CE. Almagest catalogued hundreds of stars and a few hazy cloud-like objects, one of which was the Andromeda galaxy. The reader will also encounter in this book well-known figures such as William Herschel, who, along with his sister Caroline (the first professional female astronomer), discovered hundreds of galaxies and lay the foundations for modern galaxy studies, as well as lesser-known astronomers, including tenth-century Persian astronomer Abd al-Rahman al-Sufi, twentieth-century American astronomer Vesto Melvin Slipher, and others. Galaxies concludes by showing readers how they can get involved in galaxy studies themselves and do their part to fight the light pollution that today obscures the Milky Way and all but the brightest of stars. Providing a brief but broad overview of galaxies for the nonspecialist, Galaxies shows just how modern science is done and what the future holds for this specific field of astronomy.