Ophiuchus was deliberately left out of the original zodiac, over 2000 years ago, even though the Sun clearly passes in front of it after passing in front of Scorpius (commonly known as Scorpio) and before reaching Sagittarius. The reason for this is not known, but it may be because ancient astrologers wanted to divide the 360 degree path of the Sun in a mathematically pleasing way –12 equal parts, each one of 30 degrees.2000年前,尽管太阳在经过天蝎座(英文Scorpius通常写作Scorpio)后光明正大地在蛇夫座面前经过,并朝着射手座方向前进,蛇夫座还是被人故意从原有的星座中剔除。其原因不得而知,但可能是因为古占星家想用比较方便的算术法来划分太阳的360度运动路径——分成12等份,每部分30度。