What is the origin of Frost Descent? How was the Frost Descent solar term established?

What is the origin of Frost Descent? Frost Descent, one of the 24 solar terms, falls around October 23rd of the Gregorian calendar every year. Next, let’s take a look at the origin of the Frost Descent solar term and related content.

What is the origin of frost?

General Overview

1. Frost Descent refers to one of the 24 solar terms. It occurs around October 23rd of the Gregorian calendar every year when the sun reaches 210° of the ecliptic longitude.
2. Frost Descent means that the weather is getting colder and the first frost appears, which also indicates that winter is coming. "Collected Explanations of the 72 Seasonal Changes" says: In the middle of September, the air is cold and condensed, and the dew turns into frost.
3. The time of Frost Descent in 2017: October 23, 13:26:36, the fifth day of the ninth month (big month) in the lunar calendar of 2017

Twenty-four solar terms

1. The 24 solar terms are divided according to the position of the sun on the ecliptic (the orbit of the earth around the sun).
2. As early as the Spring and Autumn Period and the Warring States Period, Chinese working people had used a gnomon (a pole erected on a flat surface) to measure the length of the midday sun's shadow in order to determine the 24 solar terms.
3. In 104 BC, the Taichu Calendar formulated by Deng Ping and others officially included the 24 solar terms in the calendar and clarified the astronomical positions of the 24 solar terms. And everyone will follow the 24 solar terms in production activities, so the lunar calendar is also called the "Xia calendar."

Three signs of frost

The first phase is when jackals offer sacrifices to animals: this means that jackals and other ferocious animals will first display their captured prey on the ground, offer sacrifices to the sky, and then eat it. The Yi Zhou Shu Shi Xun says: "On the day of frost, jackals offer sacrifices to animals." It also says: "If jackals do not offer sacrifices to animals, their claws and teeth will be bad."
The second phase is the yellowing and falling of grass and trees: this means that the grass and trees on the earth begin to turn yellow and shed their leaves. After the Frost Descent, the weather gradually becomes colder, and most plants stop fully supplying water and nutrients to nourish them. As a result, their leaves gradually turn yellow and fall to the ground.
The third sign is that all the stinging insects are lying down in hibernation: this means that the insects that have been stinging and hibernating are hiding in the soil or holes, not moving, not calling, and not eating, with their heads down and their bodies bent, entering a hibernation state. The Huainanzi Tianwen Xun records: "In the third month of autumn, the earth's qi is no longer hidden, and it stops killing. All insects hibernate, and people stay at home and close their doors. Then the Green Lady comes out and brings frost and snow."