Open AccessOn the function and the probable origin of Ptolemy’s equant
Author(s) -
James J. Evans
Publication year - 1984
Publication title -
american journal of physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.541
H-Index - 99
eISSN - 1943-2909
pISSN - 0002-9505
DOI - 10.1119/1.13764
Subject(s) - ptolemy's table of chords , mars exploration program , physics , function (biology) , astrobiology , history , evolutionary biology , classics , biology
We examine the roles of the equant point and the eccentric deferent circle in Ptolemy’s planetary theory. The necessity of these features of the model is demonstrated empirically by a study of the retrograde arcs of Mars. Finally, these results are used, together with available historical evidence, to suggest the line of investigation that probably led Ptolemy to his discovery of the equant.
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