Ophiuchus is considered to the 13th sign of the zodiac by sidereal astrologers, according to Astrodienst. Sidereal astrology is based on constellations rather than traditional astrology which is based on the seasons. A sidereal horoscope can be obtained for those who fall under the sign of Ophiuchus. Traditional astrologers do not consider Ophiuchus to be a zodiac sign, so there are no traditional horoscopes for the sign.
Ophiuchus is the Serpent Bearer in sidereal astrology. Some people who are considered a Sagittarius in traditional astrology are considered Ophiuchus by sidereal astrology. To fall under the sign of Opiuchus, a person is born between November 29 and December 17. In traditional astrology, the constellations assigned to each sign have no actual bearing on the sign, and they are considered to be irrelevant. Because there is a slight shift each year in the position of each fixed star constellation, this makes the constellations an unreliable base for astrology.
The sun signs of traditional astrology correspond to the 30-degree mathematical division of the annual path of the sun through the sky. Traditional astrological signs represent the cardinal points in the four seasons, including the beginning, middle and end. Three points per season during the four seasons equals the twelve traditional signs of the zodiac.