The law of moon phase change in ancient poetry (from the first day to the thirtieth day of the lunar calendar)

New moon → Mumeiyue → First quarter moon → Convex moon → Full moon → Convex moon → Lower quarter moon → Mumeiyue → New moon. There is no moon on the first day, and the full moon is around 15 and 16. The moon phase is calculated by the difference between the sun and the moon (the following degrees are the difference between the sun and the moon), and there are eight kinds of * * *: new moon (the first day of the lunar calendar, that is, the first day of the lunar calendar): 0 degrees; Emei month (usually from the second day to the seventh day of the second lunar month): 0 to 90; First quarter moon (about the eighth day of the eighth lunar month, that is, half moon): 90; Full moon (9th to 14th day of the 9th lunar month): 90-180; Full moon (the fifteenth or sixteenth day of the lunar calendar, that is, looking at the sun):180; Monthly deficit (around 16th to 23rd lunar month): 180 to 270; First quarter moon (about twenty-three months of the lunar calendar, half moon): 270; The waning moon (around the 24th lunar month to the end of the month): 270-360; In addition, the last day of the lunar month is called a dark day, that is, you can't see the moon. Attachment: The new moon on the first day of "Song of the Moon Phase Change" is invisible only because it is trapped between the sun and the earth. On the eighth day of the seventh lunar month, the half moon faces west. When the full moon comes out on the 15th and 16th, the earth shoulders the sun and the moon. Twenty-two, three and the last quarter of the moon, the moon faces east until midnight.