Editing Equation of time (section)

=== Early astronomy ===
The irregular daily movement of the Sun was known to the Babylonians.{{citation needed|date=May 2020}}

Book III of [[Ptolemy]]'s ''[[Almagest]]'' (2nd century) is primarily concerned with the Sun's anomaly, and he tabulated the equation of time in his ''Handy Tables''.<ref>{{Citation | last = Neugebauer | first = Otto | author-link = Otto Neugebauer | date = 1975 | title = A History of Ancient Mathematical Astronomy | publisher = Springer-Verlag | location = New York / Heidelberg / Berlin | pages = 984–986 | isbn = 978-0-387-06995-1 |series=Studies in the History of Mathematics and Physical Sciences |volume=1 |doi=10.1007/978-3-642-61910-6}}</ref> Ptolemy discusses the correction needed to convert the meridian crossing of the Sun to mean solar time and takes into consideration the nonuniform motion of the Sun along the ecliptic and the meridian correction for the Sun's ecliptic longitude. He states the maximum correction is {{frac|8|1|3}}&nbsp;time-degrees or {{frac|5|9}} of an hour (Book III, chapter 9).<ref name="Toomer"/> However he did not consider the effect to be relevant for most calculations since it was negligible for the slow-moving luminaries and only applied it for the fastest-moving luminary, the Moon.

Based on Ptolemy's discussion in the ''[[Almagest]]'', values for the equation of time (Arabic ''taʿdīl al-ayyām bi layālayhā'') were standard for the tables (''zij'') in the works of [[medieval Islamic astronomy]].<ref>{{cite journal |last1=Kennedy |first1=E. S. |title=A Survey of Islamic Astronomical Tables |journal=Transactions of the American Philosophical Society |date=1956 |volume=46 |issue=2 |page=141 |doi=10.2307/1005726 |jstor=1005726|hdl=2027/mdp.39076006359272 |hdl-access=free }}<br/>Reprinted in: {{cite book |last1=Kennedy |first1=E. S. |title=A survey of Islamic astronomical tables |date=1989 |publisher=American Philosophical Society |location=Philadelphia, PA |isbn=9780871694621 |page=19 |edition=2nd |url=https://books.google.com/books?id=EywLAAAAIAAJ&pg=PA19}}</ref>