The origin of seven days a week

The ancient Babylonians were very good at observing things in life. By observing the moon, they found that the change of the moon is between the semi-circular moon, the full moon and the new moon. For the moon, it takes seven days from the semi-circular moon to the full moon. From the full moon to the semi-circular moon, the time is 7 days. From half a month to disappearance, the time is 7 days; It's seven days from disappearing to half a month. Seven days is also the cycle of moon's profit and loss. From this, they came to the conclusion that seven days is the cycle of the moon's profit and loss, so they divided a month into four weeks and took seven days as a cycle, which is our current week.

The ancient Babylonians first used seven days as a week unit, and later the Jews spread it to ancient Egypt and from ancient Egypt to Rome. After the 3rd century AD, it spread widely to European countries.

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The Origin of Week in China

Zhou was called the Seven Obsidian in ancient China. During the Xia, Shang and Zhou Dynasties in China, Seven Obsidian refers to the seven main stars, such as the sun, the moon and the five planets, which was an important part of astronomical astrology at that time. Later, one week was borrowed as a unit of seven days, so it was called a week. China's seven obsidians did not begin as a unit of time.

References:

Baidu encyclopedia-Zhou