Over the course of his career, John R. Christianson has shaped and sharpened our view of Tycho Brahe as a champion of observational precision who channeled his powers to promote a more collaborative and collective form of science. Among the few to master the many technical achievements of Tycho, Christianson has never lost sight of social context in his close attention to early modern court culture and Tycho's bold decisions to build his island observatory and revolving team of researchers. Given such breadth and depth, we can now appreciate a more complete picture of Tycho, one that reflects the many roles he played—activist, entrepreneur, innovator—and the resources that fueled his revolutionary enterprise. The present contribution bears witness to decades of work that delivers not only a lasting tribute to Tycho, but also a concise biography that brings to life his ideas and interactions with family and friends. Leaving some better-known events such as his bitter dispute with Nicolaus Reimers “Ursus” to other historians, Christianson turns to topics that affirm his familiar account of Tycho as a fair manager and faithful mentor to many.

Four basic themes tie the book together, beginning with the birth of Tycho and extending to his scientific legacy six chapters later. First, Christianson focuses primarily on the place of Tycho in the broader culture of the period, rounding out his role as a Renaissance figure who practiced courtly exchange at the highest level. Second, Christianson describes in vivid detail how Tycho deployed his rare talent and resources to designing the finest astronomical instruments of the day. Christianson illustrates the form and function of each instrument, including a few failures, and how Tycho arranged them on the island of Hven. In turn, Christianson explains how these instruments required a team of technicians whom Tycho cared for personally at his royal palace. It is clear that “Tycho had many irons in the fire” (197), as he managed the moving pieces of an extraordinary program to map the stars with unprecedented precision and “soar through the spheres of heaven with the Creator” (58). His creativity as a team leader caught the interest of aspiring scholars from across Europe, many of whom later taught at the University of Copenhagen long after Tycho had left Denmark in disgrace to spend his final years at the court of Holy Roman Emperor Rudolph II in Prague.

Christianson covers considerable ground, but his biography is not meant to be exhaustive. It is important to keep the mission of the author in mind when we find few details on certain subjects. Although alchemy was essential to Tycho, we barely hear about his interest in Paracelsian medicine or the virtual arsenal of instruments that filled the ground floor of Uraniborg. Equally sparse are the circumstances surrounding his sudden fall from grace at the court of King Christian IV in 1596–97. When the hopes and dreams of Tycho are “crushed in an instant” (179), there may be more to the story than a young monarch yearning to demonstrate his power over the aristocracy. Finally, there is a sense that Christianson takes his account of Tycho too far when it comes to his influence on Johannes Kepler. As much as it may serve to complement more benevolent portrayals of Kepler, Christianson exaggerates the extent to which Tycho taught Kepler about collaboration, courtesy, and “the advantages of teamwork” (204). The result is a rather harsh view of Kepler as a reclusive theoretician who, despite the patient support of his patron, had to learn to work with others the hard way.

Beautifully illustrated and brilliantly written, Tycho Brahe and the Measure of the Heavens crowns a career of research on Tycho and his times. It stands as the single best introduction to Tycho and will attract a wide audience well beyond the history of early modern science and society.