How to calculate the day when the cow falls into the fence and the pig falls into the herd?

Methods based on astronomical observation. The festival of throwing cattle and pigs is a solar term, which generally appears on the 23rd or 24th of each year, marking the beginning of sowing and cultivation of crops in spring. The calculation method is to calculate the solar ecliptic, that is, the position of the sun on the ecliptic, and then calculate the solar term time according to the difference between the solar ecliptic and the designated ecliptic. However, it is a traditional concept in rural areas of China that cows turn over fences and pigs flock together. It is believed that cows and pigs will become very weak during this period, and they can't buckle the railing backwards, so they will be squeezed into a ball.