Copernicus's Chord Tables from De Revolutionibus Orbium Coelestium

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This Demonstration reconstructs Copernicus's chord (sine) table from De revolutionibus orbium coelestium (1543), Nuremberg, by Johannes Petreius, and from Hawking's On the Shoulders of Giants. The book contains a table of chords for every ten minutes of the quadrant and for a radius of —that is, using formula . Accordingly, the chords were given to five places. Differences were also calculated.

Contributed by: Izidor Hafner (January 2016)
Open content licensed under CC BY-NC-SA



Chapters 1–11 of Book I are a general vision of the heliocentric theory and a summarized exposition of Copernicus's cosmology. The world (heavens) is spherical, as is the Earth, and the land and water make a single globe. The celestial bodies, including the Earth, have regular circular and everlasting movements. The Earth rotates on its axis and around the Sun. He answers as to why the ancients thought the Earth was central. He describes the order of the planets around the Sun and their periodicity. Chapters 12–14 give theorems for chord geometry as well as a table of chords [4].


[1] D. Roegel, "A Reconstruction of the Tables of Rheticus' Opus Palatanium (1596)," Dec 6, 2010.

[2] S. Hawking, ed., On the Shoulders of Giants, Philadelphia: Running Press, 2002.

[3] N. Copernicus, De revolutionibus orbium coelestium, Jan 21, 2016.

[4] Wikipedia. "De revolutionibus orbium coelestium." _coelestium.

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