Solar Eclipse Observations in the Time of Copernicus: Tradition or Novelty?

Eclipse observations recorded by Copernicus in his copy of Stoeffler's work were first reported by Ludwik Antoni Birkenmajer in Mikołaj Kopernik (Cracow, 1900), 546–56. Stoeffler's work is now in the Library of Uppsala Astronomical Observatory, Coll. Hjörter, G I, 51.

Birkenmajer , op. cit. (ref. 1), 552.

Ibid., 554.

Ibid., 555.

Ibid.

Sobotko Paweł , “O zaćmieniach Słońca i Księżyca obserwowanych przez Mikołaja Kopernika”, Kwartalnik historii nauki i techniki, xxxvi (1991), 153–74.

Three Copernican treatises, transl. by Rosen Edward (New York, 1971), 125.

Copernicus Nicholas , On the revolutions, transl. by Rosen Edward (Warsaw and Cracow, 1978), 162.

Birkenmajer , op. cit. (ref. 1), 296–7.

Between 1535 and 1580 the book had at least eight editions. They were published as reprints of the first edition (Wittenberg, 1551; Basel, 1569 and 1573) or the second edition, which appeared in Wittenberg in 1542 (reprinted in Wittenberg, 1553; Paris, 1557; Wittenberg, 1580). Birkenmajer did not state it explicitly, but the method was already described in the edition of 1542.

Kraai Jesse , “The newly-found Rheticus lectures”, Beiträge zur Astronomiegeschichte, i (1998), 32–40.

Reinhold Erasmus , Erasmi Reinholdi Salueldensis Theoricae novae planetarum Georgii Purbachii … recens editae et auctae novis scholiis … (Wittenberg, 1542), f. Z8.

The history of this problem has been described in a series of articles: Lindberg David C. , “The theory of pinhole images from Antiquity to the thirteenth century”, Archive for history of exact sciences, v (1968), 154–76; idem, “A reconsideration of Roger Bacon's theory of pinhole images”, Archive for history of exact sciences, vi (1970), 1970–23; idem, “The theory of pinhole images in the fourteenth century”, Archive for history of exact sciences, vi (1970), 1970–325; Goldstein Bernard R. , The astronomy of Levi ben Gerson (1288–1344) (New York and Berlin, 1985), 48–50, 140–3; Mancha José Luis , “Egidius of Baisiu's theory of pinhole images”, Archive for history of exact sciences, xl (1989), 1989–35; idem, “Astronomical use of pinhole images in William of Saint-Cloud's Almanach planetarum (1292)”, Archive for history of exact sciences, xliii (1992), 1992–98.

Wiedeman Eilhard , “Über die Camera obscura bei Ibn al Haitam”, Sitzungsberichte der Physikalischmedizinischen Sozietät in Erlangen, xlvi (1914), 155–69; The optics of Ibn al-Haytham, transl. and comment. by Sabra A. I. (London, 1989), ii, pp. xxxiii, xlix–li.

See Mancha , “Astronomical use” (ref. 13).

Ibid., 282.

Ibid.

Goldstein , op. cit. (ref. 13).

Ibid., 49–50.

Ibid., 142–3.

Mancha , “Egidius of Baisiu's theory” (ref. 13), 9–10. Egidius's treatise was presumably written before Levi's work; see ibid., 30–31.

Lindberg , “The theory of pinhole images in the fourteenth century” (ref. 13), 314–15; Mancha , “Astronomical use” (ref. 13), 286–8. Henry's work, a commentary on Pecham's Perspectiva communis, had been printed in 1500.

The solution was formulated independently at the end of the sixteenth century by the Sicilian scholar Francesco Maurolico, but it was published no earlier than in 1611. The conditions under which Kepler provided his solution of the problem are presented in a classical paper by Straker Stephen , “Kepler, Tycho, and the ‘Optical part of astronomy’: The genesis of Kepler's theory of pinhole images”, Archive for history of exact sciences, xxiv (1981), 267–93.

Straker , op. cit. (ref. 23), 269–85.

Kepler Johannes , Optics, transl. by Donahue W. H. (Santa Fe, 2000), 362–3. This quotation is from chap. 11, problem 7 of Ad Vitellionem paralipomena.

The optics of Ibn al-Haytham (ref. 14), p. xxxiii.

Said S. S. Stephenson F. R. , “Solar and lunar eclipse measurements by medieval Muslim astronomers, II: Observations”, Journal for the history of astronomy, xxviii (1997), 29–48.

ibid., 37–38, 40. There are two other solar eclipse observations reported by Ibn Yūnūs (of 993 and 1004); however in these cases magnitude was not given in linear digits but in digits of area (a fraction of the area of the solar disk). See Said S. S. Stephenson F. R. , “Solar and lunar eclipse measurements by medieval Muslim astronomers, I: Background”, Journal for the history of astronomy, xxvii (1996), 259–73, pp. 266–8.

Said Stephenson , “Solar and lunar eclipse measurements” (ref. 27), 35.

Rosińska Grażyna , Fifteenth-century optics: Between medieval and modern science (Studia Copernicana, xxiv; Wrocław, 1986), 181.

Mancha , “Egidius of Baisiu's theory” (ref. 13), 32.

Birkenmajer Ludwik Antoni , Stromata Copernicana (Cracow, 1924), 201–2.

Birkenmajer , Mikołaj Kopernik (ref. 1), 449–74. Copernicus referred the parameters of his theory to the meridian of Cracow, which he considered to be identical with that of Frauenburg. In Book IV, chap. 7 of De revolutionibus he wrote: “For Gynopolis, which is commonly called Frombork, where I generally made my observations, is located at the mouths of the Vistula River and lies on the meridian of Cracow, as I learn from lunar and solar eclipses observed simultaneously in both places.” See Copernicus , On the revolutions (ref. 8), 191. Unfortunately, details of this collaboration between Frauenburg and Cracow are unknown.

Ibid., 459–60, 471, 473.

I owe the modern data to Marek Zawilski.

Straker , op. cit. (ref. 23), 269.

Ibid., 269–70. Gemma's work became widely known when it was reissued together with a modified edition of Peter Apian's Cosmographia (Antwerp, 1584). Kepler, incidentally, noticed that Gemma's estimation of magnitude (10 digits) was incorrect: The eclipse was greater. Apparently Gemma Frisius also did not know about the error introduced by a finite aperture. See Kepler , op. cit. (ref. 25), 308.

Straker , op. cit. (ref. 23), 293.

Kepler , op. cit. (ref. 25), 57. Kepler used these words to praise Reinhold, Gemma Frisius, and Maestlin.