Construct · 1 fields · 2 citations

deferent: a standalone construct

One name. One construct. A landmark on the map.

● anchor · a standalone construct Nearest construct by meaning·not indexed
deferent1 CONSTRUCTDeferent (orbit)PTOLEMY · DEFERENT CIRCLE

A single standalone construct; nearby constructs are located against it in the Collider. Tap a field for its definition, unit, and measures.

Astronomy

The great circle in Ptolemaic theory that carries a planet's epicycle.

In geocentric (Ptolemaic) astronomy the deferent is the principal circle, centered near the Earth, along which the center of a planet's epicycle is carried; deferent and epicycle together reproduced the observed retrograde loops of the planets. The device is codified in Ptolemy's Almagest (2nd century CE) and anatomized by later scholars (see Duke's 'Epicycle-on-deferent'). Here 'deferent' is a piece of orbital geometry, sharing only the Latin root deferre ('to carry') with the anatomical duct of the same name.[1][2]

Unit
One deferent circle, measured by its radius and the eccentricity of its center from Earth.
Recovery means
Identify the large carrying circle in a two-circle (deferent + epicycle) planetary model.
Measured by
Reconstructed from the geometry fitted to observed planetary longitudes.

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Nearby constructs

carry1 fields · 1 citationsanchor · a standalone constructorbital1 fields · 1 citationsanchor · one construct, one fieldprincipal3 fields · 6 citationsjingle · one word, three constructs

References

  1. Ptolemy. (1999). Ptolemy's Almagest (G. J. Toomer, Trans.; O. Gingerich, Foreword). Princeton University Press. https://doi.org/10.1515/9780691213361
  2. Duke, D. W. (2012). Epicycle-on-deferent. In The Encyclopedia of Ancient History. Wiley. https://doi.org/10.1002/9781444338386.wbeah21128

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