Before the telescope was invented, 16th-century Danish astronomer Tycho Brahe built his own instruments to measure star and planetary positions with accuracy up to one arcminute. Brahe described these home-made instruments in his 1602 book, Astronomiae instauratae mechanica, the first edition of which is on display in the Ransom Center’s current exhibition, Other Worlds: Rare Astronomical Works. Mary Kay Hemenway, Research Associate and Senior Lecturer of the Astronomy Department at The University of Texas at Austin, explains why Brahe’s book is one of her favorite items in the exhibition.

The greatest observational astronomer before the use of the telescope is undoubtedly Tycho Brahe. Justly proud of his methods and the many instruments that he designed and had built, he wrote a book illustrating…