Solar term

The solar terms used to mark the midpoint of the month (marked with "Z", for ) are considered the major terms, while the solar terms used to mark the start of the month (marked with "J", for ) are deemed minor. The year starts with Lichun (J1) and ends with Dahan (Z12). == Multilingual list ==

The "Song of Solar Terms" () is used to ease the memorization of jieqi: ;Traditional Chinese: ;Simplified Chinese: ;Pinyin The first four lines provides a concise version of the names of the 24 jieqi. The last four lines provide some rules of thumb about the Gregorian dates of jieqi, namely: • Two jieqi per month; • Gregorian dates are off by one or two days at most; • In the first half of the year, jieqi happens around the 6th and 21st day of each (Gregorian) month; • In the second half of the year, jieqi happens around the 8th and 23rd day of each (Gregorian) month. == Determination ==

names The modern definition using ecliptic longitudes, introduced by the Shixian calendar, is known as . 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. The JPL Horizons On-Line Ephemeris System may be used to query for exact times of solar terms. The older method, called the , simply divides the tropical year into 24 equal parts. == See also ==