How did the astronomical calendar develop in Shang Dynasty?

In the Xia Dynasty, the calendar had made great progress. According to legend, the earliest calendar in China is Xia, a natural calendar compiled through observation and timing. Large-scale sacrifice and divination in Shang Dynasty need accurate time and period of sacrifice, and with the progress of agricultural production, the climate has more and more influence on agriculture, animal husbandry and hunting. It was by observing the astronomical phenomena that the merchants grasped the climate change, thus further developing the calendar of Shang Dynasty on the basis of Xia Dynasty.

The calendar of Shang Dynasty is the earliest known calendar. The calendar of Shang Dynasty is a lunar calendar: the solar calendar takes 365 days and 1/4 days as a tropic year, so it is also called a seasonal calendar. In the lunar calendar, the moon revolves around the earth once, that is, the 29th or 30th is the new moon. The Shang dynasty recorded the sun and the moon with branches and numbers; There is a big moon and a small moon, the big moon is 30 and the small moon is 29. December of the lunar calendar is a civil calendar year, which is different from the tropic year, so the lunar calendar has several leap years, and the leap month is placed at the end of the year, which is called March. There is generally a fixed system between seasons and months. In Shang dynasty, every month was divided into ten days, and every ten days was ten days. Oracle Bone Inscriptions usually records ten days, which is also called the Spring and Autumn Period. Within a day, at several times, the dawn will be bright, and there will be a bumper harvest and big food in the future; At noon, it's China and Japan, then snacks, snacks and pickpockets. At the beginning, North Korea was comparable to a great talent. Sunset is when the sun is about to set. For age, it is also called year, except for year and sacrifice. Many astronomical phenomena in Shang Dynasty were recorded in Oracle Bone Inscriptions, which provided valuable information for later generations.