The Sixteenth-Century Empirical Disproof of Ptolemaic Geocentrism

Journal of Astronomical History and Heritage 26, no. 3 (2023): 659–666. With Enrico Massaro. https://doi.org/10.3724/SP.J.1440-2807.2023.09.65

In 1573, Thomas Digges published a book entitled Alae seu Scalae Mathematicae and in 2023 we celebrate the 450th anniversary of its publication. The book was prompted by the apparition of the New Star of 1572, which Digges shows does not change position in the sky. He supplies its distances from some nearby stars in Cassiopeia, but the remainder of the book has long been under-valued. It presents a "new and unheard-of method" of ascertaining diurnal parallaxes of planets, yet Digges applies the theoretical developments only in illustrative examples. However, three years later in 1576 in an essay "A Perfit Description of the Caelestiall Orbes," Digges makes the astounding claim that he has measured parallaxes of planets with sufficient accuracy to show that they do not circle the Earth at a constant distance but have some other center or centers. This paper examines Digges’ claim of an empirical disproof of geocentrism in the sixteenth century and its support for heliocentrism.

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Work Title The Sixteenth-Century Empirical Disproof of Ptolemaic Geocentrism
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Open Access
Creators
  1. Peter D. Usher
  2. Enrico Massaro
Keyword
  1. Astronomy
  2. Sixteenth-century
  3. Thomas Digges
  4. Parallax
  5. Heliocentrism
License CC BY-NC 4.0 (Attribution-NonCommercial)
Work Type Research Paper
Publisher
  1. Journal of Astronomical History and Heritage
Publication Date October 25, 2023
Publisher Identifier (DOI)
  1. https://doi.org/10.3724/SP.J.1440-2807.2023.09.65
Deposited November 04, 2023

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    • https://creativecommons.org/licenses/by-nc/4.0/
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    Work Title
    • THE SIXTEENTH-CENTURY EMPIRICAL DISPROOF OF PTOLEMAIC GEOCENTRISM
    • The Sixteenth-Century Empirical Disproof of Ptolemaic Geocentrism
    Keyword
    • Astronomy, Sixteenth-century, Thomas Digges, Parallax, Heliocentrism
    Publisher
    • Journal of Astronomical History and Heritage
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    • Journal of Astronomical History and Heritage 26, no. 3 (2023): 659–666. With Enrico Massaro. https://doi.org/10.3724/SP.J.1440-2807.2023.09.65
    • In 1573, Thomas Digges published a book entitled Alae seu Scalae Mathematicae and in 2023 we celebrate the 450th anniversary of its publication. The book was prompted by the apparition of the New Star of 1572, which Digges shows does not change position in the sky. He supplies its distances from some nearby stars in Cassiopeia, but the remainder of the book has long been under-valued. It presents a "new and unheard-of method" of ascertaining diurnal parallaxes of planets, yet Digges applies the theoretical developments only in illustrative examples. However, three years later in 1576 in an essay "A Perfit Description of the Caelestiall Orbes," Digges makes the astounding claim that he has measured parallaxes of planets with sufficient accuracy to show that they do not circle the Earth at a constant distance but have some other center or centers. This paper examines Digges’ claim of an empirical disproof of geocentrism in the sixteenth century and its support for heliocentrism.
  • Published
  • Updated