What achievements did Shen Kuo make in presiding over the work of Tianjian Supervision Department?

Shen Kuo presided over the work of Tianjian Supervision Department, studied precession, and initiated the "Twelve-qi Calendar", which advocated abandoning the lunar calendar and adopting the solar calendar. Twelve solar terms are used to represent twelve months, because the period of the moon's orbit around the earth is 29.50588 days and the period of the earth's orbit around the sun is 365.38+06 days. These two numbers cannot be divided by all. Earlier, the leap month method was adopted, and in 2009, 65438+7 leap was adopted to reconcile this contradiction. The "Twelve solar terms" calendar initiated by Shen Kuo is more ideal than the current "Gregorian calendar".