Galileo's Lunar Observations and the Dating of the Composition of “Sidereus Nuncius”

Righini G. , “New Light on Galileo's Lunar Observations”, in Bonelli M. L. and Shea W. R. , Reason, experiment and mysticism in the Scientific Revolution (New York, 1975), 59–76. This book is reviewed by North J. D. in Journal for the history of astronomy, ix (1978), 67–68.

Gingerich O. , “Dissertatio cum Professore Righini et Sidereo Nuncio”, in Bonelli and Shea , op. cit., 77–88.

Drake S. , “Galileo's First Telescopic Observations”, in Journal for the history of astronomy, vii (1976), 153–168.

Gingerich , op. cit., 87–88.

Favaro A. (ed.), Le opere di Galileo Galilei, national edition (Florence, 1890–1909), iii, part 1, 48.

On p. 88 of his paper, Gingerich, who has examined the original document, notes that two horoscopes occupy another part of this sheet, one complete and the other unfinished. He finds that these correspond to the date 1590 May 2. More recently Righini, in an article in the new Annalen series from the Florence Science Museum, independently arrives at the same date for the horoscopes, and notes that this is the birth date of Cosimo II de' Medici, to whom Sidereus nuncius is dedicated.

Galileo , Opere, x, 274–6.

Righini , op. cit., 67; the letter is given in Opere, x, 262–3.

Drake , op. cit., 154.

Gingerich , op. cit., 88.

Opere, iii, part 1, 53–96.

Ibid., 17–50.

Drake , op. cit., 155–8; a complete translation.

Opere, iii, part 1, 9.

Righini , op. cit., 66.

Opere, iii, part 1, 17 and 60; also, The Sidereal Messenger of Galileo Galilei, translated by Carlos E. S. (1880, reprinted London, 1959), 9.

Drake , op. cit., 165. Favaro also favours this date; see Opere, iii, part 2, 403.

Drake , op. cit., 156.

Opere, iii, part 1, 18.

Opere, iii, part 2, 430, 432 and 433.

Tuckerman B. , Planetary, lunar and solar positions A.D. 2 to A.D. 1649 , which is Memoirs of the American Philosophical Society, lix (1964).

Opere, iii, part 2, 431.

Gingerich , op. cit., 88.

In his drawing of the asterism of Orion's head, Galileo clearly shows BD −9° 883 and 888, visual mags. 8·4 and 8·5; see Opere, iii, part 2, 964.

Drake , op. cit., 154.

After an excellent account of the lunar librations and Galileo's prediction and subsequent detection of these, on p. 63 the words “latitude” and “longitude” are everywhere interchanged which completely falsifies the information. On p. 61, Galileo uses “east” and “west” in the traditional sense, i.e. left and right respectively, but on p. 62 Righini uses the post-1960 sense without referring to the change. In his Table 3 he identifies three features that Galileo draws at the terminator (numbered 1, 2 and 4) with crater groups at longitudes 30°, 23° and 17°, an impossibly large spread. The crater “Airy” should read “Baily”, in “Lacus Somniorum”. In his Table 4, the values for the libration in latitude are not quite correct, being merely the lunar celestial latitude with the sign changed. On p. 75, for “Maurilius” read “Manilius”.

Carlos E. S. (trans.), op. cit. (ref. 16), 45.

Ibid., 41.

Opere, iii, part 2, 430.

Ibid., 962 and 964.

Opere, x, 280–1 and 282–4.

Opere, iii, part 1, 47.

Opere, x, 288–9.

Ibid., 297.

Drake , op. cit., 154.

This sketch is reproduced in Terrie Bloom's paper, “Borrowed Perceptions: Harriot's Maps of the Moon”, in Journal for the history of astronomy, ix (1978), 117–22.

This point is dealt with at greater length in Bloom's paper, where the conclusion reached is that although Harriot's first lunar observation was made before Galileo's, he failed to appreciate or interpret the new phenomena presented to him—a point with which I fully concur. However, I do not agree that Harriot's sketch dated 1610 July 17 was probably much influenced by his prior knowledge of the Galileo sketch (E2). The Sun's colongitude at 9 p.m. on that date was about 357°·5, only 0°·5 less than that for Galileo's observing date of 1609 December 3. Furthermore, the crater Maurolycus is well shown in Harriot's sketch, with Barocius, Gemma Frisius, Licetus, Cuvier, Aliacensis, Apianus and Playfair recognizable. None of these is identifiable in Galileo's sketch.