Every few years, the nonsense about the "13th sign" comes up again and Astrologers sigh, shake their heads and wait for the panicky questions from people who are worried that their "sign has changed." Nasa do this periodically to try and discredit Astrology, claiming Astrologers "ignore" certain constellations.
The zodiac (Greek zodiakos, meaning "circle of animals." wheel was created with 12 sections (spanning the ecliptic) and they are not aligned with the constellations, but based on the seasonal changes - the equinoxes, solstices and the periods in-between. Western or tropical astrology was not created to be in alignment with the constellations. The tropical zodiac is fixed to the seasons and does not move.
It is always people with zero working knowledge with astrology who continue to perpetuate this myth. Ptolemy was very clear about this issue in his famous astrological work, the "tetrabiblos." For example, the properties of tropical zodiac sign of Cancer are vastly different than those of the constellation of Cancer. Some of the stars within the constellation are said to have the nature of Mars and Saturn.
All astrologers, both tropical and sidereal are aware of the precession of the equinoxes and the Tropical or Western zodiac is independent of the constellations so not affected by the shift. The Greeks didn't use the constellations to measure the positions of the planets because then the ecliptic wouldn't have been divided into equal portions.
The Greeks knew about the equinox precessions but it didn't matter as their astrology at the time was based entirely on the energy of the seasons. Sidereal astrology takes into consideration the precession of the equinoxes, not Tropical or Western astrology. Tropical astrology gets its interpretation of the signs from the seasons, not the fixed stars. If you live in Europe, the energies of the seasons are strongly felt by all, even astrology sceptics.
Any astrology chart cast in Greek times would still be totally accurate today as the charts aren't affected by any shift. The confusion comes from the fact that the 12 Tropical signs share the same names as the constellations, and Nasa and other critics of astrology use this as a way to attack Astrology but they, and annoying commenters on Youtube, get the Tropical system totally wrong. As I said before, the Greeks didn't use the constellations in this way, in their zodiac system.
Tropical astrology divides the zodiac wheel into 30 degree sections. Scorpio was picked as the 8th sign and this makes senses from a numerological and metaphysical perspective. Scorpio is the sign connected with death, and during Scorpio season, the natural world is dying and the leaves and flowers are rotting. The 30 degree divisions are energetic, and not physical points, but energy is very real. So the difference lies between Tropical and Sidereal astrology.
Both are accurate and valid systems which are used successfully by Astrologers all over the world. Both systems place importance on different aspects of astrology. Western astrologers use the fixed, tropical zodiac. Some western astrologers, like myself, also use the fixed stars. I use both the parans method which is the original method that the mesopotamians worked with, and the Ptolemaic calculations.
Ophiuchus does not feature in the tropical zodiac as it is a constellation. To deny the accuracy of Tropical astrology is to deny the effect that the seasons have on our daily lives. So your sign is still the same.
The western zodiac wheel is based on the seasons and equinoxes. In fact, it is essentially a solar calendar that reflects the polytheistic wheel of the year on earth.
P.S - Western Astrologers are aware that there has always been a constellation named Ophiuchus.
P.P.S Tabloids, Nasa and women's magazines aren't the best places to find real information on Astrology, which has been studied and practiced for over 5,000 years.