Talk:History of astronomy/Common misconceptions

message: Beginning students in the history of science are commonly warned of the danger of writing Whig history; that is, the danger of writing about the past from a present perspective.  One problem with Whig history is that it becomes a principle of selection, which is especially dangerous in writing a summary like an encyclopedia.  As Herbert Butterfield said:
:If we can exclude certain things on the ground that they have no direct bearing on the present, we have removed the most troublesome elements in the complexity [of history] and the crooked is made straight.Herbert Butterfield, The Whig Interpretation of History, (New York: W. W. Norton, 1965; [London, 1931]) p. 25
This principle of selection dominates Wikipedia's history of astronomy articles, as editors choose to discuss those elements where past authors anticipated modern ideas, and ignore the rest.  As an example, compare the discussion of al-Biruni's astronomy with the sourceKhwarizm, Foundation for Science Technology and Civilisation. on which it is chiefly based.  In the Wikipedia article, more than half of the section on astronomy (12 out or 21 lines) deals with heliocentrism or gravity; in the principle source 11 out of 36 lines deal with his discussion of the possible rotation of the earth; there are no further discussions of heliocentrism or gravity.  
Further examples could be made by comparing Wikipedia's presentations with those of other scholarly encyclopedias, such as the Dictionary of Scientific Biography or the Encyclopedia of Islam. A survey of the essays in Walker's Astronomy Before the Telescope by David Pingree, "Astronomy in India" and David A. King, "Islamic Astronomy"Christopher Walker, ed., Astronomy Before the Telescope, London: British Museum Press, 1996, pp. 123-142, 143-173, shows that the question of heliocentrism is only briefly mentioned in one page (p. 150) that discusses the work of al-Tusi and his followers and its possible influence on Copernicus while elliptical orbits are briefly mentioned on another (p. 128) to contrast Indian dual-epicycle models with modern ones.
Yet in Wikipedia, due to this presentist principle of selection, we find discussions of certain modern topics dominating articles on the history of ancient and medieval astronomy:
* Anticipations of heliocentrism
* Anticipations of the rotation of the Earth
* Anticipations of elliptical orbits
* Anticipations of the concept of gravitation
These anticipations are selected to such an extent that the reader of these articles could come away almost totally unaware of the questions and methods governing early investigations of celestial phenomena.
* That their inquiry followed the model of geometrical astronomy, based on combinations of uniform circular motions, that is first documented in the writings of Hipparchus and Ptolemy.
* That the criticisms they levelled at their predecessors (such as Ptolemy) were framed within that model of geometrical astronomy.
In sum, by selecting material from the perspective of the present, we are in danger of writing a history, which, while accurate in detail, presents a false overall picture.
--SteveMcCluskey 14:09, 14 June 2007 (UTC)
thread_title:  Whig history in ''Wikipedia'' 

message: :One item in Ibn al-Zarqālluh's book [the Libro de las láminas de los siete planetas] is its description of the method used to draw Mercury's deferent which, in this instrument, is a non-circular curve....  The curve drawn following this procedure is described, in the Alfonsine translationof Ibn al-Zarqālluh's words, as follows: "et sera el çerco del leuador figura de taiadura menguada de las taiaduras que uienien en la figura pinnonata."...  The translation of the aforementioned Alfonsine Castilian text is, then: "The deferent circle will have the shape of the deficient section [ellipse], of those sections which appear in the pineal figure [cone]."
:Now we also know that Ibn al-Zarqālluh identified this curve as an ellipse and this is the first instance, to the best of our knowledge, of the use of such a conic section in astronomy, even if the eleventh-century Toledan astronomer had no theoretical pretensions in his use of an ellipse and employed it only to simplify his design of an equatorium.
:A systematic attempt has been made, however, to see if a model based on elliptic deferent could have been used to calculate the tables of equations for Mercury in Andalusian, medieval Spanish, and Maghribi astronomical tables....  The results obtained have been negative: all the tables considered derive their Mercury equation tables from [Ptolemy's] Handy tables.Julio Samsó and Honorino Mielgo, "Ibn al-Zarqālluh on Mercury," Journal for the History of Astronomy, 25(1994): 289-96 --SteveMcCluskey (talk) 21:48, 10 April 2010 (UTC)
thread_title:  Julio Samsó and Honorino Mielgo (1994) 

message: :[al-Biruni] goes as far as to imply that the heavens could have an elliptical motion without contradicting the tenets of medieval physics.  Again, criticizing Aristotle on this point he writes [Nasr then quotes a different translation of the discussion with ibn-Sina quoted below at al-Biruni (11th c. [2004]), italicizing the significant conclusion]:
:Aristotle has mentioned in his second article that the elliptical an lentil-shaped figures need a vacuuum in order to have circular motion, and a sphere has no need of a vacuum....  For ir we make the axis of rotation of the ellipse the major axis and the axis of rotation of the lentil-shaped figure the minor axis, they will revolve like a sphere and have no need of a void.  The objedction of Aristotle and his statement become true in the case where we make the minor axis of the ellipse and the axis of fotation of the lentil-shaped figure...  I am not saying according to my belief that the shape of the great heavens is not spherical, but elliptical or lentil-shaped.  I have made copious studies to reject this view, but I wonder at the logicians.S. H. Nasr, Introduction to Islamic Cosmological Doctrines, (Cambridge: Belknap Press of Harvard Univ. Pr., 1964), p. 170.
[It is noteable that Nasr's discussion speaks of elliptical motion, while the text he quotes speaks only of the circular motion of an elliptical body. SteveMcCluskey 15:33, 15 June 2007 (UTC)
thread_title:  S. H. Nasr (1964) 

message: :After this general review of the planetary theories which were developed by Arabic writing astronomers after the twelfth century, it has become clear that the two major achievements of this long tradition were,... two mathematical theorems: ... `Urdī's lemma and ... the so-called Tūsī Couple.  With the help of these two theorems ... it was possible to transfer segments of these [Ptolemaic] models from the central parts to the peripheries and back.  This freedom of movement not only allowed the retention of the effect of the equant in the Ptolemaic models, but also allowed the development of sets of uniform [circular] motions that would not violate any physical principles.  The Tūsī Couple allowed, in addition, the production of linear motion as a combination of circular motions,...George Saliba, "Arabic plandtary theories after the eleventh century AD", pp. 58-127 in Roshdi Rashed, ed., Encyclopedia of the History of Arabic Science, (London: Routledge, 1996), p. 125  [Note that Saliba makes no mention of ellipses in his lengthy study, a point which also applies to the discussion of al-Biruni's "elliptical orbits", below] --SteveMcCluskey 20:49, 20 June 2007 (UTC)
thread_title:  George Saliba (1996)