Talk:Al-Zarqali

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==The footnote 1 is missing.==

Encyclopedia Britannica states "Al-Zarqali also anticipated Johannes Kepler by suggesting that the orbits of the planets are not circular but ovoid." Ovoid is egg-shaped. (http://www.britannica.com/eb/article-70382/Spain) "Relativity: an introduction to the special theory" author, Asghar Qadir does state that Al-Zarqali had a sun-centered model with the planets in elliptical orbits. TedHuntington 22:31, 30 May 2007 (UTC)

Thanks, I added the Notes section now. --SteveMcCluskey 20:50, 31 May 2007 (UTC)

''''Bold text'

Variety

There is a variety regarding the achievements and works completed by Abū Ishāq Ibrāhīm al-Zarqālī, they must be elaborated accordingly, his works cannot just be divided into "Theory" and "Astronomy". — Preceding unsigned comment added by Mughal Lohar (talk • contribs) 20:56, 8 October 2011 (UTC)

Ellipses?

I've checked the reference to the book by Ashgar Qadir and find he makes this, and a number of other, dubious and undocumented historical assertions in the introductory section to a book on physics. This claim, which contradicts the nature of Al-Zarqali's astronomical model based on eccentric circles and epicycles as used in the Tables of Toledo and as described in the discussion of his measurement in the solar apogee should either be fully documented or removed. --SteveMcCluskey 20:54, 31 May 2007 (UTC)

There is a similar claim that al-Biruni that advocated elliptical orbits which, when checked, indicates a very different connection with ellipses and celestial spheres. I don't know if that's what's going on regarding Arzachel but given the nature of medieval cosmological concerns, it seems very likely. See the discussion at Talk:Abū Rayhān al-Bīrūnī#Elliptical orbits?. --SteveMcCluskey 20:57, 5 June 2007 (UTC)

I've just come across a reference to a claim by Peurbach that the center of the epicycle of Mercury travels in an oval path. This refers to the complex motion of Mercury which Ptolemy had explained using a complicated crank mechanism. This source (E. J. Aiton, "Peurbach's Theoricae Novae Planetarum: A Translation with Commentary", Osiris, 2nd Series, Vol. 3. (1987), pp. 4-43, at p. 26) also notes (n. 71) that "it had been so described by al-Zarqali". Again, this would not be a claim for elliptical orbits of the planets since

1. The path is egg-shaped, not elliptical,
2. The path is that of the center of the epicycle, not of the planet,
3. It only applies to Mercury, not to all the planets.

--SteveMcCluskey 21:41, 5 June 2007 (UTC)

PS The source to which Aiton refers in the article cited above is Willy Hartner, "The mercury horoscope of marcantonio Michel of Venice: A study in the History of Renaissance astrology and astronomy," Vistas in Astronomy, 1 (1955): 84-138 ( doi:10.1016/0083-6656(55)90016-7 ). The following appears in the abstract of Hartner's paper:

The second part of the paper discussed the history and development of Ptolemy's theory of Mercury. In a degression the algebraic curve described by the centre of Mercury's epicycle is analysed. It is shown that this curve is practically interchangeable with the ellipse. The curve appears for the first time in a treatise by Azarquiel (eleventh century) which is preserved in a Spanish translation incorporated in the Libros Saber. European historians, with the exception of A. Wegener (1905), have failed to recognize the true significance of this curve, which is by no means an anticipation of Kepler's ellipse though it may have one of the stimuli that led to his experimenting with oval (elliptiform) curves.

In sum, al-Zarqali did not describe elliptical orbits for the planets. --SteveMcCluskey 22:04, 5 June 2007 (UTC)

Request for evidence

I have recently looked for sources supporting and criticizing a number of myths appearing in discussions concerning the History of astronomy. If you know of any sources related to these myths, please add them to the discussion at Talk:History of astronomy/Common misconceptions. --SteveMcCluskey 20:01, 9 June 2007 (UTC)

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