How are constellations formed?

The twelve constellations originated from Greek mythology. Constellation originated in Babylon, one of the four ancient civilizations. The ancient Babylonians divided the sky into many regions and called them "constellations", but at that time constellations were of little use, and they were not found and named. The constellation 12 on the ecliptic was originally used to measure time, not to express people's character as it is now.

In 922, the General Assembly of the International Astronomical Union decided to divide the sky into 88 constellations, whose names are basically consistent with historical names. 1928, the international astronomical union officially announced the names of 88 constellations. These 88 constellations are divided into three celestial regions, 29 in the northern hemisphere, 47 in the southern hemisphere, and near the equator and ecliptic 12.

Just as some ethnic groups in East Asia define a person's zodiac according to the animals represented by the year of birth, in many countries, a person's birth month corresponds to a constellation. Birth constellation comes from astrology, trying to explain people's character and destiny by using their birthplace, birth time and celestial position.

Because the orbit of celestial bodies is different from the Gregorian calendar, there will be a difference of 1-2 days in different years, which is consistent with the distance of "festival" in the twenty-four solar terms of the China lunar calendar. The calculation of solar term time is accurate to minutes (not midnight), which is also the boundary of the constellation, and it varies from year to year.