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Astrolabe replica (Brian Grieg)

The astrolabe, one of the fundamental instruments for observational astronomy, consists of three major parts: the mater, or underlying disk; the climate, a removable disk adjusted for latitude; and the rete, a ring marked with star positions. The removable climate disk in this astrolabe corresponds to OU’s latitude of 35°N. The rete displays 29 stars. One may tell time with this astrolabe to within 20 minutes.

This astrolabe replica consists of acid-etched brass plates. The mater is one centimeter thick and 25 cm in diameter. Two climate disks are designed for the northern hemisphere, one for 10°N (the latitude for a sea route through the Bay of Bengal in the Indian Ocean) and the other for 35°N, the latitude of OU. The rete displays 29 stars.

Galileo's World Exhibition Location

Source: History of Science Collections

Section: Observational Astronomy

Section Number: 6

Object Number: 26

Subject Area(s): Astronomy, Scientific Instruments

Time Period: Ancient to Renaissance

Region(s): Europe, Italy

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Exhibit Gallery OERs

Coma Berenices Learning Leaflet

Coma Berenices Learning Leaflet

Coma Berenices is the only one of the modern 88 official constellations named after a historical figure. It represents the hair of Berenice, Queen of Egypt (267 221 BCE), who reigned with Ptolemy III Euergetes. Learn more about this in this learning leaflet.


Discorso particolare intorno all'unisono

Vincenzo Musical Score

Vincenzo Galilei was among the first music theorists to advocate for a new system of tuning based on performance, instead of the mathematical principles of music set fourth by Pythagoras. Pythagorean music theory bases pitch on the mathematical proportions of dividing a string. Vincenzo's primary problem with this system is that, although it is great for the mathematician and the music theorist, it is impractical for the performer. All music based on this particular system of tuning would inevitably sound out of tune and unpleasant. In this learning leaflet learn about the tuning systems in the late-Renaissance period.


Pythagorean Solids: Five Regular Solids

Pythagorean Solids Learning Leaflet

Can you identify the five regular solids? 

Throughout history the regular solids were studied with keen interest by astronomers, mathematicians, artists, architects and philosophers. The Pythagoreans proved that there are only five regular solids: the cube, triangle, octahedron, dodecahedron, and icosahedron. 


Johann Kepler: Blueprints of the Universe

Kepler-Blueprints Learning Leaflet

Is there a mathematical basis of the universe? 

Johann Kepler's "Mystery of the Universe" is one of the brilliant illustrations in the history of astronomy. Kepler used the five regular Pythagorean solids to refute the major objections to Copernicanism. In this work he demonstrated that vast empty regions lying between the planetary spheres, which were required by Copernicus, were not wasted space. Rather, these gaps perfectly matched, within the limits of observational error, the geometry of the 5 regular Pythagorean solids. 


Astronomy & Music: Introduction to the Duochord

Duochord Learning Leaflet

Can you identify simple musical intervals? 

The ancient Pythagoreans envisioned the heavens as a musical scale, comprised of celestial spheres rotating according to harmonious music. For Robert Fludd, a seventeenth-century physician, the universe was a monochord, its physical structure unintelligible without an understanding of music. In this activity, explore the relationship between mathematics, astronomy, and music.