Today is the 16th solar term, the Autumn Equinox. Just like the Spring Equinox, the daytime equals the nighttime in length on this occasion when the sun is exactly at the celestial longitude of 180°. And the sunlight shines vertically on the equator. Then the sunlight comes straight down to the south of the equator. Gradually on the northern hemisphere the daytime gets shorter and nighttime becomes longer. And the daily temperature will decline with time. As the old saying goes, it gets colder after each autumn rain. The Autumn Equinox divides the autumn into two halves. According to the farmer's  proverb in North China, it is time to sow the winter wheat in the region.