Editing Solar term (section)

== Determination ==
{{See also|Ecliptic#Sun's apparent motion}}
[[File:Tiết Khí.svg|thumb|Chart with the solar terms and their [[Vietnamese language|Vietnamese]] names]]
The modern definition using ecliptic longitudes, introduced by the [[Shixian calendar]], is known as {{lang|zh-Hans|定气法}} ({{Transliteration|zh|pinyin|dìng qì fǎ}}, {{gloss|steady term method}}). Under this method, the determination of solar terms is similar to the astronomical determination of the special cases of [[equinox]] and [[solstice]] dates, with different ecliptic longitudes to solve for. One can start with an approximation and then perform a correction using the anomalies and [[mean motion]] of the sun.<ref>{{cite web |title=Determination of Equinox and Solstice Dates |url=http://farside.ph.utexas.edu/Books/Syntaxis/Almagest/node36.html |website=farside.ph.utexas.edu}}</ref> The [[JPL Horizons On-Line Ephemeris System]] may be used to query for exact times of solar terms.

The older method is known as {{lang|zh-Hans|平气法}}  ({{Transliteration|zh|pinyin|píng qì fǎ}}, {{gloss|equal term method}}) and simply divides the [[tropical year]] into 24 equal parts.