Rambam- The Zodiacs- Yisodei Hatorah perek 3 halacha 6

The Rambam describes how the Zodiacs are made up and described. He says,


גלגל התשיעי שהוא מקיף את הכל חלקוהו החכמים הקדמונים לשנים עשר חלקים, כל חלק וחלק העלו לו שם על שם צורה זו שתראה בו מן הכוכבים שלמטה ממנו שהם מכוונים תחתיו. והם המזלות ששמותם. טלה. שור. תאומים. סרטן. אריה. בתולה. מאזנים. עקרב. קשת. גדי. דלי. דגים:


"The ninth Sphere, that encompasses everything, was split into twelve parts by the first scholars. Every one [of the twelve divisions] was given a name based on the form that appeared in it from its stars that are below [the Sphere in that area] because [that image] is beneath it. These are the Zodiac that their names are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius and Pisces."

The reason the Rambam says that the ninth sphere was divided into twelve parts was because really it is all of the stars found in the eighth sphere that is included in these divisions. The Zodiacs are just the constellations in the sky and by talking about them, the Rambam is not saying they have any power or anything of the sort. They are only used as reference to describe the different areas of outer space.