The basis of constellation division

Constellations are divided according to the solar calendar.

Basis: When the earth rotates once, the trajectory (90 degrees) of the sun on the earth is called the ecliptic, and the belt-shaped area around the earth formed within 9 degrees above and below the ecliptic is called the ecliptic. The 12 constellation in the sky corresponding to the ecliptic is called 12 constellation (solar constellation), which is the 12 constellation we discussed.

Of course, in astronomy, there are 13 constellations on the ecliptic, but ancient astrologers only chose 12 constellations (Ophiuchus is not in the ecliptic).