From the story –
Is Ophiuchus the 13th zodiac sign?When this story first broke I remember seeing a local blogger linking to it (I think it was the Fox story if memory serves) with a headline that said something like “idiot pagans.” Because that turned me off so much I just never bothered looking into the story. Then yesterday at work someone brought it up and showed me this new list of the signs, so I decided to look up what my horoscope is today (because it appeared to have changed) and discovered that no it hadn’t and that all of this is a just another case of misinformation gone wild online.
No. Ophiuchus is just a constellation. Even the founding text for astrology (Tetrabiblos by Claudius Ptolemy, written 170 AD) mentions just 12 signs. Though a very small fraction of western astrologers who follow a different, constellation-based zodiac, or those who follow Vedic astrology, may use Ophiuchus as the 13th zodiac sign, or assign different dates to the signs used in western astrology.
How did this whole myth get started?
It began when astronomy professor Parke Kunkle of Minneapolis Community and Technical College told the Minneapolis Star-Tribune about the procession of stars over time. He said "Three thousand years ago the sun was 'in' whatever it was in. Now it's about a whole constellation off from that." Kunkle's quote was picked up by FOX News and other media outlets, and the false information went viral because people mistakenly assume that astrology is based on the constellations. But that's not true at all.
So what is the truth?
Western astrology is based on the four seasons, not on constellations -- and the seasons don't change. As Levine said above, there are four seasons, each with a with a beginning, middle and end, which adds up to 12 zodiac signs. There is no 13th sign. Period.