Ophiuchus has sometimes been suggested in sidereal astrology as a 13th astrological sign in addition to the 12 signs of the tropical zodiac. The constellation Ophiuchus, as defined by the 1930 International Astronomical Union's constellation boundaries, is situated behind the Sun from November 29 to December 18.

Historically, astrological and astronomical symbols have overlapped. Frequently used symbols include signs of the zodiac and classical planets. These originate from medieval Byzantine codices. Their current form is a product of the European Renaissance. Other symbols for astrological aspects are used in various astrological traditions.