Music of the Spheres
Observational Astronomy
For thousands of years before the telescope, astronomers observed the stars and planets, predicting their movements and mapping locations on the surface of the Earth. The astronomer’s toolkit contained remarkably capable instruments, including the sundial, astrolabe, celestial sphere, armillary sphere, quadrant, sextant and orrery.
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Tellurian, Trippensee Planetarium Company (1908-1920) |
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Sundial replica (2015) A sundial consists of a gnomon, which casts the Sun’s shadow, and a dial on which the shadow indicates the time. This simple portable sundial features a gnomon that can be adjusted according to one’s latitude. Sundials have ranged in size from pocket-dials to monumental architecture. |
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Polyhedral Sundial replica This is a replica of an original polyhedral sundial created by Stefano Buonsignori in Florence in 1587, held in the Museo Galileo in Florence. |
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Astronomical Calendar, 1476 Regiomontanus, (1476) In this book, Regiomontanus predicted the positions of the Sun and Moon for 40 years. He designed a sundial to work independently of one’s latitude, and a volvelle, or circular dial, to locate the position and phase of the Moon according to date and time. |
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Astronomical Calendar, 1518 Stoeffler, Johann (1518) A “calendarium” contains predictions of the positions of the Sun and Moon for several decades into the future. Regiomontanus calculated their positions for 40 years beginning in 1476; Stoeffler for 62 years from 1518-1579 inclusive. |
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Innovative Sundials Baldi, Bernardino (ca. 1592) This manuscript, a never-published treatise on sundials written in the author’s own hand, was lost in the 18th century and believed destroyed in a shipwreck. Baldi studied with one of Galileo’s teachers, Guidobaldo del Monte. |
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Nocturnal Dial replica (2006) Nocturnal dials tell time by the stars. This instrument replicates an original nocturnal dial created by Girolano della Volpaia in Florence in 1569, held in the Museo Galileo in Florence. |
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Complex Armillary Sphere replica An armillary sphere is a spherical astrolabe, showing the great circles in their unflattened orientation: The great circle of the ecliptic (the path of the Sun) is marked off in degrees of celestial longitude and in the 12 signs of the Zodiac. |
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Astrolabe replica (2015) The astrolabe, one of the fundamental instruments for observational astronomy, consists of three major parts: the mater, the underlying disk; the climate, a removable disk adjusted for latitude; and the rete, a ring marked with star positions. |
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On the Use and Fabrication of the Astrolabe Danti, Egnazio (1578) Danti was a cosmographer in the court of Cosimo I de Medici. Visitors to Florence today may view his stunning maps of the world in the Hall of Maps of the Palazzo Vecchio, as well as armillary spheres and a quadrant he mounted on the facade of the church of Santa Maria Novella. |
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Introduction to the Astrolabe Lansbergen, Philip van (1635) Astronomers use astrolabes for dozens of astronomical operations including telling time by the Sun or stars and determining the positions of planets. |
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On the Quadrant Lansbergen, Philip van (1635) Astronomers use quadrants and sextants to measure angular distances in the night sky, such as the angular divergence between a planet and the nearest bright star. One may also measure the height of the North Star above the horizon, which is equal to one’s latitude on the Earth. |
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Sextant replica An astronomer might use a sextant or quadrant to measure the distance between a planet and a notable bright star, or the altitude of a star above the horizon. |
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Description and Use of Both the Globes, the Armillary Sphere, and Orrery Martin, Benjamin (ca. 1760) This book explains how to use the terrestrial and celestial globes, an armillary sphere (which shows the movements of the sky), and an orrery (which models the motions of the planets). Martin operated an instrument shop in London. |
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Delamarche Orrery An orrery, also called a planetarium, shows the choreography of planets as they dance with coordinated precision around the Sun. From antiquity, geocentric (Earth-centered) models of the moving planets were constructed, such as the Antikythera device and large mechanical clocks. |
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Astronomy Explained upon Sir Isaac Newton's Principles Ferguson, James (1809) Ferguson’s books, orreries, clocks and mechanical devices were studied with interest by Benjamin Franklin, Thomas Paine and William Herschel, among others. |
