This book showcases a wide-ranging study of the comets of 1618. That year came to be regarded as a turning point in European history, marking the start of the Thirty Years’ War, which was the most destructive conflict since ancient Roman times. Even while the Great Comet dominated the night sky in late 1618 and early 1619, the printing presses of Europe began disseminating news about it. With the combined effort of 11 leading scholars in the history of astronomy, this book details the tremendous influence on human affairs made by the Great Comet and its two less luminous predecessors. Geographically-focused studies are presented on how the comets were studied in Spain, India and China. In England and The Netherlands, the tremendous creation of poetry sparked by the Great Comet is examined in-depth, with implications ranging from religion and politics to the death of members of the Royal Family and the origins of the English Civil War. The first study of an unpublished manuscript from Germany, among the most significant interventions on the comet of 1618, is presented with its magnificent color illustrations. Other chapters take a broader look on how the comets affected European thought in the visual and cultural arena, shedding new light on the dynamic and complex relationship between natural knowledge, world view, and forms of belief. Ultimately, this book is written for researchers in historical astronomy and will be an interesting read for armchair astronomers, professionals, historians, and students alike.