Early Astronomy in the University of Michigan Collections

Born into a Danish aristocratic family, Tycho Brahe would devote his life to astronomy rather than the court. After completing three years of studies at the University of Copenhagen, from 1562 to 1576 Brahe continued to pursue his interest in astronomy in the German universities of Leipzig, Wittenberg, and Rostock. During those years, Brahe also collaborated with other astronomers in Basel, Augsburg, and Kassel. The appearance of a supernova (new star) in 1572 inspired his first publication: Tychonis Brahe Dani de nova et nullius ævi memoria prius visa stella iam pridem anno à nato Christo 1572, mense Nouembri primùm conspecta. Copenhagen: Lorenz Benedicht, 1573. By the time Brahe delivered his lectures on astronomy at the University of Copenhagen in 1574, he had already conceptualized his cosmological system. While he admitted that the Copernican system was mathematically, and geometrically, superior to that of Ptolemy, thus accepting that the Moon orbits the Earth and that the planets orbit the Sun, he still believed that the Sun orbits the Earth. In 1576, at the request of King Frederick II, Brahe left his permanent residence in Basel to take over the administration of the Island of Hven, where he built two observatories, Uraniborg and Stjerneborg. With the accession of King Christian IV, Brahe lost royal support, obliging him to leave Denmark in 1597. Two years later, he settled near Prague, having been named Imperial Mathematician by Emperor Rudolph II. Johannes Kepler joined him in 1600, one year before Brahe’s death.

Tycho Brahe’s legacy is mostly based on his building of a wide range of astronomical instruments of great accuracy in the two observatories of the Island of Hven. These instruments were described in his Tychonis Brahe Astronomiae instauratae mechanica (The Astronomical Instruments of Tycho Brahe’s Restored Astronomy), first published in 1598. Our copy includes an ownership inscription at the bottom of the page: Sum Samuelis Caroli Kechelii: I belong to Samuel Carolus Kechelius [van Hollensteijn (1611-1668)], an astronomer from Leiden. What do we know about Kechelius? He might have had a good reputation as a scholar. A manuscript treatise on the principles of geometry (Benginsel der geometrie) by Kechelius is held at the University of Leiden; and a chalk drawing by Dirk Druyf (1638-1682) depicts him with an armillary sphere in the background.

Zodiacal Armillaries

Equatorial Armillaries

Quadrants

Brahe and Kepler