Why is the auspicious day of each month found in the yellow calendar different?

The so-called auspicious days of the zodiac are all artificially fabricated and have no scientific basis. Of course, each said his own words. Almanac can only be used as a reference, not credible. Just as Tathagata is an Indian, so is his image. There are many westerners in Jesus, so his image becomes a westerner with a high nose and deep purpose. They are all artificial.