"Since astronomer Parke Kunkle dropped his little bombshell on NBC News this week that changes in the Earth’s alignment had created a 13th zodiac sign called Ophiuchus, I’ve been deluged with questions from perplexed folks. Has my sun sign really changed? What the heck is Ophiuchus, and how do you pronounce it anyway?
Ophiuchus (O-fee-uh-kus), the Serpent Holder, has been known to astrologers since ancient times. His toe touches the ecliptic (the path of the 12 major constellations) though the bulk of the Serpent Holder lies above the other constellations. If you were practicing sidereal astrology (as do the Vedic astrologers of India) in which the planets are located by constellation, it could conceivably make sense to include Ophiuchus.
But in Western astrology, we locate planets based on the seasons, not the constellations. About 4000 years ago, when on the first day of Spring the Sun was in the constellation of Aries, the two systems coincided. Now, because of precession (the slow wobble of the Earth on its axis), the Sun enters the Spring equinox in the sign of Aries but the constellation of Pisces. The systems are now approximately 23 degrees apart. Therefore, unless you were born very late in the sign, your Sun sign indeed shifts backwards in the sidereal system. A Virgo becoming a Leo? Unthinkable! Yet in the Vedic system, it makes sense."