Except if you read the stuff Agrias posted on facebook then you'll see that this isn't really real. The Zodiac isn't based on the stars and sun, it's based on seasons and well since 3000 years ago when it was created we may not have had the same calendar or the same name for the months damn it even the length of the week may have changed but we've still had due to the gravitational lock of Earth to the Sun the same seasons, Spring, Summer, Autumn, Winter with each having a beginning, middle and end. The way the Zodiac works is there is 3 symbols for each season one for the beginning of the season, one for the middle and one for the end. This makes it pretty impossible to have a 13th Zodiac sign, unless ofcourse the gravitational pull of the Sun on the Earth lessened thus increasing the number of seasons because it'd increase the length of the year however doing so might move the earth out of the sweet spot it's in with regards to heat and light from the sun killing us all which is where greenhouse gases and global warming would actually work in our favour since they would help protect the earth as it cools due to increased distance from the Sun.

Ophiuchus is merely a star constellation not a Zodiac sign. God could you imagine if it was? They'd have to go back and re-write everything including tactics to include 13 Zodiac Braves!