Back مزدوجة الطوسي Arabic Tusi cütü Azerbaijani তুসি যুগল Bengali/Bangla Tusijev par BS Parell de Tussí Catalan Cardanische Kreise German Acople Tusi Spanish جفت طوسی Persian Théorème de La Hire French Tandem Tusi ID

Tusi couple

An animated model of a Tusi couple

The Tusi couple (also known as Tusi's mechanism[1][2][3]) is a mathematical device in which a small circle rotates inside a larger circle twice the diameter of the smaller circle. Rotations of the circles cause a point on the circumference of the smaller circle to oscillate back and forth in linear motion along a diameter of the larger circle. The Tusi couple is a 2-cusped hypocycloid.

The couple was first proposed by the 13th-century Persian astronomer and mathematician Nasir al-Din al-Tusi in his 1247 Tahrir al-Majisti (Commentary on the Almagest) as a solution for the latitudinal motion of the inferior planets[4] and later used extensively as a substitute for the equant introduced over a thousand years earlier in Ptolemy's Almagest.[5][6]

  1. ^ Roshdi Rashed (ed.). Encyclopedia Of The History Of Arabic Science.
  2. ^ Saliba, George (2002-07-01). "Greek astronomy and the medieval Arabic tradition: the medieval Islamic astronomers were not merely translators. They may also have played a key role in the Copernican revolution". American Scientist. 90 (4): 360–368. doi:10.1511/2002.27.360.
  3. ^ Nosonovsky, Michael (2018-08-14). "Abner of Burgos: The Missing Link between Nasir al-Din al-Tusi and Nicolaus Copernicus?". Zutot. 15 (1): 25–30. doi:10.1163/18750214-12151070. ISSN 1571-7283. S2CID 135358186.
  4. ^ George Saliba (1995), "A History of Arabic Astronomy: Planetary Theories During the Golden Age of Islam", pp. 152–155.
  5. ^ "Late Medieval Planetary Theory", E. S. Kennedy, Isis 57, #3 (Autumn 1966), 365–378, JSTOR 228366.
  6. ^ Craig G. Fraser, "The cosmos: a historical perspective", Greenwood Publishing Group, 2006 p. 39.

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