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Are the Signs of the Zodiac Wrong? Is Ophiuchus the 13th sign?

From time to time, rookie journalists report on an "amazing new discovery" ... the signs of the zodiac are wrong or misaligned or that there are missing signs! It's a story that makes headlines every few years, but it is not news. In fact it is a hoax.

In 1995, this 'dramatic news' broke in London from a publicity stunt.[1] Then again, like a virus that reinfects, the story broke in January 2011. In 2011 an astronomy professor 'revealed' to the Minneapolis Star-Tribune that the Earth's "wobble" has shifted the zodiac signs.[2] Now in 2015, comedian and amateur scientist, Dara O'Briain has fallen for the urban myth and posted it on the BBC iWonder information page.[3]

It is a simple gaffe. The signs of the Zodiac (Tropical Zodiac) are confused with the constellations of the Zodiac. Journalists who don't know any better believe they have a sensational scoop.

Since the facts are significant for astronomy, the history of science and for astrology, it's important to set the record straight.

The 12 Sign Tropical Zodiac has remained unchanged for two thousand years!

Simple Explanation:

Western astrology is based on the position of the planets measured within zones defined by the path of the Sun as seen from Earth rather than the apparent pattern of the more distant stars.

About 2,500 years ago a proto-type of the modern twelve sign zodiac was identified by stargazing scholars in the region around what is today, Iraq using the position of the stars within the constellations at the time.

The stars appear to be creeping backwards out of line with the Earth's seasons and year in a process known as the Precession of the Equinox. So to establish a stable measuring system, Ptolemy in the second century in Alexandria, firmly established the Tropical Zodiac starting from Aries at the position of the Sun at the March Equinox. So, the Tropical Zodiac is fixed and not affected by shifts in the Earth's axis. However, Ptolemy used the same or similar names[4] for the signs as the constellations (artificial groups of unrelated stars) in his ingenious updated system.

Meanwhile, Indian astrologers retained a (sidereal) zodiac based on loosely on the stars. This resulted in two different zodiacs with the same sign names. However, both zodiacs have remained accurate and consistent measuring devices for nearly two millennia. When the two zodiacs shift to a full sign apart, we will enter what is described as the Age of Aquarius.
Claudius Ptolemy, astronomer & astrologer

More technical Explanation:

Western astrology is based on the planets and their motion relative to our year (the Earth's annual orbit of the Sun) and not on the distant stars. Before astrologers started to compile planetary tables, the backdrop of the distant visible 'fixed' stars proved to be most consistent system for measuring the positions of the 'wandering stars', known as the planets in our solar system. The 12 sign zodiac was defined by the stars within chosen constellations along the ecliptic (the apparent annual path of the Sun) in Mesopotamia at the end of the Iron Age (around 500 BC). Though the Babylonians used stars and constellations for measurement, they were also using zones which start from the position of the Sun at the March Equinox which was, is and will always be the start of the sign of Aries in the western system.

The problem with the old visible star based measurement is that the stellar positions are slowly moving backwards relative to the Earth's seasons and year at the rate of approximately 1º every 72 years. This slippage is known as the Precession of the Equinox and it is why some believe that we are in the Age of Pisces and moving into the Age of Aquarius. Though precession was probably identified long before, it was first known to have been measured by Greek astrologer and astronomer, Hipparchus (ca.140 BC).

Astrology became defined by time rather than by (outer) space

Three hundred years later, Ptolemy, astronomer, astrologer and cartographer in Alexandria fixed the Western Tropical Zodiac to the Equinoxes and Solstices to prevent it slipping significantly out of alignment in centuries to come. This mathematical construct enables astrologers to position planets by celestial latitude within the original astrological zones known as the signs of the Zodiac. Confusion now comes from the fact that Ptolemy kept the original sign names which were based on the archetypally inspired yet scientifically artificial constellations.

Since then the Tropical Zodiac has proved to be a reliable and accurate measuring system used by both astrologers and astronomers. Even though astronomers now mainly use the equatorial system, they still use tropical coordinates in what they call the ecliptic coordinate system (yes! - the same western zodiac measured in degrees from Zero Aries or the Vernal Equinox Point) to track the Sun, Moon and planets. If it is reliable enough for NASA, it should be good enough for astrologers.

Three Systems: Tropical Signs, Sidereal Signs and Astronomical Constellations

Meanwhile in India, Hindu astrologers retained the sidereal (star) based zodiac and in 1930, the International Astronomical Union (IAU) defined the boundaries of 88 constellations.[5] An important difference between these two star oriented zodiacs is that the sidereal zodiac divides the signs into twelve equally spaced sections of 30°, while the IAU boundaries are based strictly on the stellar arrangements. In the IAU definition a constellation such as Virgo is many times larger than the constellation of Aries, for example.

Just because the three different celestial positioning systems use the same labels and origin, it does not mean that only one is correct. These are different measurements for different models. It's like saying that because the US gallon and the Imperial gallon are different measurements, they can't both be right. This is a false criticism of a series of homonyms.[6] Or if a foot is a measure of twelve inches or 30.48 centimetres, can a foot also be the part of the body? Since a human foot varies in length - is only one correct? Comparisons between the sidereal and tropical zodiac are more like comparing two languages, French and German - it would be nonsense to claim that only one language is valid.

"Criticising Astrology because the Constellations shift against the Signs of the Zodiac is a bit like claiming World Maps are wrong because Magnetic North shifts - it does, but that's irrelevant!" ~ Chris Mitchell Tutor on the MA Cultural Astronomy and Astrology course at the University of Wales.
Astrologers have known this since before the year zero and any astronomer who has studied the history of their field should also know this. It is a straw man argument.
"In Western astrology, the astrological signs are determined by the position of the Sun in the sky, not the absolute positions of the constellations. Refuting a doctrine that astrologers don't hold seems, at best, ancillary and probably irrelevant to any attack on astrology," ~ Professor Darin Hayton Science Historian

Why the constellation of Ophiuchus is not zodiacal material:

  1. The Astronomical Case:

    Depictions of Ophiuchus show the giant wrestling with a serpent with one and sometimes both feet crossing the ecliptic. This incursion is reflected in the constellational borders as defined by the International Astronomical Union (IAU).

    Since the western zodiac signs are based on archetypes that evolved from pre-historic times that were projected onto constellations and not vice-versa, astronomical arguments that Ophiuchus should become a Sign of the Zodiac are irrelevant.

    If it was based on astronomy, there are several other constellations around the ecliptic that could have been included in the Zodiac. The most obvious candidate is Orion with a rich mythological history and, as proposed by astronomer, Neil de Grasse Tyson, the constellation of Cetus also touches the ecliptic.[7] A Belgian astronomer, Luc Désamoré has shown that the orbit of Venus passes through 25 constellations.[8]

    One of the problems is that the IAU imposed strict artificial boundaries despite overlaps between constellations - you can clearly see that Ophiuchus' left foot is on top of the Scorpion. But all this detail is a red herring, this zodiac is more about designation than position.
    If a spectator of a football match has his foot on the pitch just over the touch line, does that qualify him as a player? Of course not!

  2. Historical Precedent?

    The historical argument in support of Ophiuchus, made by an author promoting his book on the 13th sign, is that the constellation was mentioned by Ptolemy. That is correct, but so were 48 constellations listed in Almagest and Tetrabiblos but only 12 were allocated by Ptolemy in the Tropical Zodiac.

  3. Numerical Symbolism?

    A symbolic case for a 13th sign is based on 13 rotations of the moon around the Earth per year. However, astrology has more emphasis on Lunations (A complete Lunar Cycle starting at a New Moon) and there are never more than 12 per year. Lunations are Soli-Lunar based on the cycle of the Sun and the Moon.

    Another problem with 13 signs - it simply does not fit the model. Every astrologer knows the value and importance of the matrix of 3 modes by 4 elements forming the unique blend of twelve signs.

    Ophiuchus has been twice suggested for the Zodiac by astronomers, who know no more about astrology than the average reader of sun sign columns. I know - I met Jacqueline Mitton who proposed Ophiuchus in 1995 in a Press Release promoting a new BBC TV series on astronomy. Mitton, an astronomer and delightful lady told me she and her husband enjoyed reading their 'stars' "for a bit of fun" in the newspapers! The 13th sign was a hoax in 1995 then and it remains a hoax.

Though this outline is accurate to the best of my knowledge, this is only part of the story. My own take is that the mythology of the surrounding constellations are part of the archetypal nature of the sign. So Ophiuchus is really the healing, heroic part of Scorpio, Cetus is related to Aries/Taurus, Orion to Taurus and Sextans to Leo. I hope to publish the full story as soon as I have completed my research.

~Robert Currey


If you are ever confused about astrology, seek advice from an expert in the field. Don't rely on the media, magicians, sceptics and now after these debacles, not even astronomers. Unless they have studied astrology, they remain amateurs.

More reliable Press Reports on the subject came from the BBC and CNN, simply because the journalists bothered to consult astrologers.

BBC: Have the Zodiac and star signs changed?

CNN: No, your zodiac sign hasn't changed.
    Here's a classic example where following advice from amateurs led to confusion:-
  • Bad Science: How a best-selling author, Jodi Picoult managed to fall for this hoax and mislead her readers.


  1. The hoax first appeared as a publicity stunt for a BBC astronomy show. At the time, I was running the Astrology Shop in central London. This led to a series of interviews from the world's media. Later that day, I started to receive calls from friends and customers around the world telling me that they had seen me interviewed on the main news on CNN, ITV or their local TV station.
  2. Ward, Bill (January 2011) Sign of the times: Astrology story soars like a comet. Minneapolis Star Tribune. "Countless people were astonished by the "news" in Monday's Star Tribune in which Minneapolis astronomy instructor Parke Kunkle affirmed that the Earth's "wobble" has shifted the zodiac signs. The buzz has raced across the Web like a shooting star." Had Kunkle explained that there are three celestial positioning systems and that it it is not the Signs that have changed, but the constellations, he would not have caused such misunderstanding. The Tribune adds "Kunkle, meanwhile, is ready to brush off the whole brouhaha. 'This has been,' he said, 'an exhausting hoot.'" However his blunder left some followers of astrology confused and astronomers looking as if they are ill-informed about the basics of their subject and out of touch with the world-view of others. One commentator on the Huffington Post wrote: "It is disingenuous - This is a hoax. Let's promote knowledge of history instead of ignorance and confusion about it."
  3. The BBC iWonder article was written by an anti-astrologer comedian who is neither an expert in astronomy or astrology. I wrote to the BBC to point out 23 errors and misleading claims (contrary to the BBC charter). Paul Kettle of the BBC Complaints Management and Editorial Standards explained that article was "from an astronomical perspective and not astrological." and that "The aim of the article was not to conclude that the Zodiac is wrong" and "It does not conclude that star signs are invalid." So why have journalists tried to use the article to claim otherwise?
  4. Ten of the twelve signs of the Zodiac have the same names as constellations. Scorpius and Capricornus are constellations and Scorpio and Capricorn are signs of the zodiac.
  5. Eugène Delporte originally listed the 88 "modern" constellations on behalf of the IAU Commission 3 (Astronomical Notations), in Délimitation scientifique des constellations. (Delporte, 1930)
  6. Homonyms: words of the same pronounciation or spelling but with different meanings. The signs and constellations are also heteronyms: the same spelling but different meaning.
  7. "The fourteenth constellation in the set is Cetus. It is a large constellation that dips into Pisces. The Sun passes through Cetus briefly as it ambles through Pisces, but you are not normally informed of this in the horoscope pages." Tyson, Neil de Grasse (1994) Universe Down to Earth Columbia University Press. In a well written article published in 2009 on the Astrology News Service site entitled "Tyson's Zodiac: Are There Really 14 Signs?". Diana K Rosenberg deftly shows that Dr Tyson is in error even on purely astronomical grounds.
  8. Luc Désamoré (2011)"My calculations showed that ... Venus passes (not often) through Auriga, Canis Minor, Serpens and also Aquila." Quand les planètes quittent le zodiaque Le Ciel, Octobre 2005, Vol.67, pp.302-316 Also, Aquarius, Capricornus, Crater, Leo, Orion, Ophiuchus, Pisces, Scutum, Virgo.

Robert Currey

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Notes for Technical Geeks

    Celestial objects in the solar system are measured by three fundamental coordinate systems:
  • The Horizon System which is the oldest and measures positions by altitude (height) and azimuth. This method was most likely used to construct the pyramids.
  • The Ecliptic System which positions planets by celestial latitude (from latin Latitudo width) and longitude (from Latin Longitudo length).
  • The Equatorial System which positions stars by declination and right ascension. The term declination comes from the Latin - to bend away or to deviate and was used to measure the distance between the oblique circle (the ecliptic) and the celestial equator. Right Ascension (ascencio recta) was originally a measure of the time it takes for objects and signs on the ecliptic to rise - at a time when determining heliacal rising was important. This was measured from the equator which rose at right angles to the horizon. This measure helped to define signs of long and short asenscion. As the equatorial system came to be used to position stars from Tycho Brahe (who used both systems in his star maps) onwards, Declination and Right Ascension were used as coordinates with reference to the celestial equator. It may also be the word Climate comes from Greek Klima (slope or region) which may refer to the slope of the Sun as it rises and falls against the equatorial plane.

Source: Woolard, Edgar W. (1942) The Historical Development of Celestial Co-ordinate Systems Publications of the Astronomical Society of the Pacific, Vol. 54, No. 318, p.77

Polaris: "I am constant as the northern star,
Of whose true fixed and resting quality
There is no fellow in the firmament."

Julius Caesar, William Shakespeare's Julius Caesar, III.1.65-68

In an article entitled, No your zodiac sign hasn't changed, the CNN writer advises Libras: "If they adhered to the tropical zodiac - which, if they're a Westerner, they probably did - absolutely nothing has changed for them. That's worth rephrasing: If you considered yourself a Cancer under the tropical zodiac last week, you're still a Cancer under the same zodiac this week."

Did NASA change the signs?
No! This is another false rumour circulating from an article in Cosmopolitian (UK). A NASA spokesman, Dwayne Brown, confirmed: ‘Nasa studies astronomy not astrology.’
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