Bronze statue of John Tang
Author Lantai
Every Qingming Festival, the Internet has to set off a debate about whether the current lunar calendar is revised by the Western missionary John Tang based on Western astronomical knowledge.
Some people say that the current "twenty-four solar terms" were invented Chinese in addition to the name, and the core is already Western astronomical knowledge; while opponents believe that the "twenty-four solar terms" are unique to China's concept of "solar terms" invented according to agricultural production, and that Tang John and others in the late Ming Dynasty only revised it based on Western astronomical knowledge.
So, was the current lunar calendar revised by the Western missionary John Tong based on Western astronomical knowledge?
This starts with the traditional Chinese calendar.
The traditional Chinese calendar is not a thin one or two pages, but a thick book, which is mainly the astronomical and mathematical knowledge of calendar calculation, in modern terms, the ancient almanac is actually a textbook, all about the deduction of mathematical formulas and models in the sky, really not the "Heluo book, innate gossip" in everyone's mind.
Then Qin Tianjian used this textbook to calculate astronomical phenomena such as solar eclipses and lunar eclipses, but because China had lagged behind for a long time in astronomy, mathematics, including geometry, the formulas and models of the traditional Chinese calendar became more and more inaccurate the more they came, just as John Tang ridiculed at the end of the Ming Dynasty, the "Great Unified Calendar" of Kublai Khan's era reached two days at the end of the Ming Dynasty.
Specific to the twenty-four solar terms, the so-called "twenty-four solar terms" are actually the position reached by the sun every fifteen degrees of operation on the ecliptic, and running 360 degrees is an annual cycle.
(Qingming, one of the twenty-four solar terms)
Before John Tang introduced the Digu astronomical system in the late Ming Dynasty, the Traditional Chinese use of the "Pingqi Method", that is, the number of days in a year was divided into 24 parts on average, and each part was a solar term. To put it bluntly, the "flat gas method" is the average time method, and the time between each solar term is fixed. And on this basis, the lunar month is determined.
This advantage is convenience, the disadvantage is naturally inaccurate, because the sun is elliptical, how can it be evenly divided?
The use of the "calm gas method" cannot guarantee the shortest day and longest night at the winter solstice, the longest night at the summer solstice, and the equal equinox between day and night at the spring equinox and autumn equinox.
This disadvantage was discovered by Chinese astronomers as early as the Southern and Northern Dynasties, and the Northern Qi astronomer Zhang Zixin found that "the day is late after the spring equinox, and the speed is after the autumn equinox." ”
Although Zhang Zixin's specific measurement of the delay of the day is not very correct, and the description and interpretation of this astronomical phenomenon is still very naïve, it is the earliest description of the uneven movement of the sun and the five stars in ancient China.
However, although Zhang Zixin described this astronomical phenomenon, in the various traditional calendars that followed, China's traditional astronomers still used the "calm gas method" that has been proved backward and unscientific.
During the Chongzhen period of the Ming Dynasty, Xu Guangqi, who was proficient in astronomy, was ordered to write a new calendar, and Xu Guangqi had close relations with the Western missionaries Matteo Ricci, Tang Ruowang and others at that time, so this time when compiling the new calendar, advanced Western astronomical knowledge was introduced as the guide, specific to the "twenty-four solar terms", Tang John and others adopted the "definite gas method".
The so-called "gas method" is determined according to the position of the sun on the returning ecliptic, that is, on a "zodiac" with a 360-degree circumference (the apparent path of the sun on the celestial sphere during the year), starting from the vernal equinox of 0 degrees, and every 15 degrees of the sun on the ecliptic is a "solar term", and each "solar term" time is not equal.
In other words, after John Tang replaced the traditional Chinese "pingqi method" with the "fixed gas method", the real "lunar calendar" began to appear, because the previous "lunar calendar" used the "pingqi method", and the "pingqi method" had no way to accurately divide the solar terms.
In a sense, whether the "twenty-four solar terms" was formulated by the German John Tang is a bit similar to the question of "The Ship of Theseus", which depends entirely on how you think of John Tang replacing the traditional Chinese "calm gas method" with the "fixed gas method".
However, in any case, one thing is clear, the traditional Chinese "calm gas method" is certainly no way to accurately divide the solar terms.
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