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12 vs. 13 Sign Astrology

Star-gazing, the oldest science

The Problem(s) with 12 Sign Astrology

12 sign astrology is historically, mathematically and scientifically inaccurate. It is so obviously incorrect that it makes the study of astrology itself an easy target for ridicule from astronomers, astrophysicists, cosmologists, and scientists who can reasonably claim that all astrology is a pseudo-science, a superstition and a scam. Astronomers can point to 12 sign or "tropical" astrology as the poster boy of delusion and confusion.

That's because when anyone tries to use tropical, 12 sign astrology to calculate the positions of the planets, the results will be catastrophically wrong. There will be a gap of over 30 degrees between the verifiable astronomical position of any given planet or celestial body and the tropical astrological position. Astrology in general takes the hit, because of tropical astrology's errors. Yet, the failure of 12 sign astrology should not discourage us from the study of astrology itself. The results for both astronomer and the astrologer should be identical. From the earliest times, the original astronomers were astrologers. Both have always used the same sky as a reference point, so what happened to astrology to make it a scientific joke?

The fall of astrology into disrepute is the fault of an outworn method of calculating the horoscope, the tropical method, which is just plain wrong in its assertions. There's no other way to state this fact. Tropical astrology can't tell you what sign you are. It calls 80% of the people it serves the wrong sign, and the rest, the wrong degree. Tropical astrology is wrong about everything but the aspects. That's because it uses a bad ephemeris--the table of the planetary positions that astrologers need to calculate horoscopes. Bad ephemeris, bad astrology!

Tropical astrologers have been using the wrong ephemeris for so long they don't even bother to check their findings against the visual reality. It only takes one look at the night sky to expose the inaccuracy of tropical astrology. You can verify this yourself by stellar observation or with any star finder map (like Stellarium, the free planetarium application). It's hard to overlook the glaring error, yet tropical astrologers manage to succeed in telling people they can't even trust their own eyes! Many tropicalists will simply defend themselves by saying it doesn't matter, or insist that the signs don't have to be correct. They are asking the impossible. Once you have seen their errors, you can't un-see them.

It's astonishing that tropical astrology has been able to keep up the facade. No wonder that their system of astrology is reviled and mocked by science as just plain rubbish.

How has tropical astrology gone bad? It's all due to a small anomaly called the precession of the equinoxes--a slight variation in the tilt of the Earth as it rotates on its North-South axis. This phenomena makes the vernal equinox travel backwards along the ecliptic, a little bit every year. In effect, the Zodiac changes position as viewed from Earth, and is not constant year after year. Over thousands of years, the first day of Spring will change, and in fact will start earlier and earlier as time goes on. This will result in the Earth showing a different face to the Zodiac as time passes, which will change our view of the positions of the planets against the backdrop of the Zodiac and the stars. This alters the dates when planets change Zodiac signs over the course of the precession. Tropical astrology has not kept up with these changes and has paid the price in accuracy.

This oversight has irrevocably destroyed the credibility of tropical astrology and 12 sign astrologers, but it has also given astrology as a whole a bad rep. What good is astrology if it can't tell you your sign? The out-of-date tropical system is not just a harmless debacle, it's a rabbit-hole from which there is no graceful exit. Tropical astrologers have trapped themselves in a death spiral of misinformation. It has led them into a series of oversimplifications and truncations that is killing astrology for the rest of us. Unless something is done, astrology itself, the oldest science in our human history, is doomed.

Bill Nye: Scorpio Or Sagittarius?

The Science Guy debunks Tropical astrology in
this 4 minute video.

Why 13 Signs?

Ancient astrology was based on the Moon. Lunar cycles have 13 months of 28 days apiece. All ancient civilizations once used the Lunar calendar. Today, we use the Solar calendar, but this does not give anyone the right to alter the Zodiac to a 12 base system. This was done for convenience, not for accuracy. The Roman Empire decided to change astrology, and in doing so, they ruined it. The reason? They wanted to destroy the power-base of women as equal members of society, and used astrology to subjugate them. The Roman astrologer Ptolemy did his part in this by removing the female goddess Ophiuchus from the Zodiac. The Greeks had actually previously changed Ophiuchus into a man, but by removing the eponymous "healer" from the Zodiac altogether, Ptolemy completed the transformation of it into a weapon against women, also institutionalizing Leo, Aries and Taurus as animal symbols instead of their original female representations, who were the equal to men.

The Roman patriarchy used astrology as propaganda against powerful female tribal chieftains and to subjugate Roman women into the narrow confines of wives and prostitutes.

Thirteen is a number long associated with the Moon, women, magic, witches and Shamans, and is part of a lunar matriarchal society that presaged the Roman empire. It's no accident that the number 13 has been called evil, unlucky, demonic, the mark of Lucifer, etc., since the church, established to support the Holy Roman Empire, was just another means used to suppress women.

By rejecting Ophiuchus, the Romans were able to dehumanize females who owned land, and kill those who resisted male domination. Ptolemy pumped astrology up with testosterone and gave the Aries god of war an Imperial stamp on the world, first in line forever–or so he thought. The war of the sexes was on.

What transpired was 2,000 years of the persecution of women, from bondage to the bonfire. Religions and cultures evolved around Man's hatred and fear of witches, cats, snakes, and a woman's sex organs. Even the menstrual period, the basis for the lunar calendar, was regarded as unclean and ungodly. Fertility, long the realm of female wisdom, was centered not around the womb, but the penis.

When Ophiuchus is brought back into the Zodiacal table, astrology will be inclusive of the female perspective, bringing it closer to its origins, and the truth of women's immense participation in human civilization.

The Romans officiated a brutal, murderous backlash against women that wiped out the female leadership of the indigenous peoples in Europe. They legitimized the expulsion of the 13th sign, Ophiuchus, from the Zodiac. They were afraid of the shaman, the snake-handler, female tribal leaders and land owners, midwives, herbalists--any woman possessing female wisdom and a higher consciousness. Shamans were once exclusively females, until men started disguising themselves as women in order to discretely practice shamanic lore themselves. However, historically, both men and women were murdered for the crime of sorcery, which in reality were the practices of the natural healer.

The rejection of Ophiuchus from Zodiacal calculations and the downfall of the lunar-based matriarchy occurred at the same time, and for the same reasons: men wanted to usurp the power of strong women. Men have since killed and tortured countless women accused of witchery, as they worked assiduously to suppress Ophiuchus from our Zodiac--and ultimately, from our minds. This is what you're buying into when you use an astrology based on Roman imperialism!

Just one look at the Zodiac supports the inclusion of Ophiuchus in the ecliptic.

Proof: Ophiuchus is part of the Zodiac

Ophiuchus (oh-few-kuss)

NASA also confirms the 13th sign-Ophiuchus

Yet, today's 12 sign astrologers continue to deny that Ophiuchus is part of the Zodiac. To ignore this powerful female snake goddess and healer is a choice they make to perpetuate the injustice and brutality of the defunct Roman Empire.

The loss of Ophiuchus, the wrong cusps, the traveling vernal equinox, these are all factors in the failure of tropical astrologers to answer the basic question, what is your sign? Rather then question the problems with their system, tropical astrologers prefer to live in a bubble, rejecting astronomy and mathematical accuracy.

The 13-sign system is a much-needed correction of Ptolemy’s poorly conceived 12-sign Tropical system. 13-sign charts unite astrology and astronomy again, for the first time in 2,000 years. 

12-sign and 13-sign systems are NOT just different but equal: one is a lie and the other, the truth. There is only one correct answer: the 13-sign astronomically true answer.

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How Rome Screwed Astrology

The tropical system is based on Roman astrologer Ptolemy's ephemeris, which he wrote around 100 A.C.E. This was Ptolemy's second biggest failure, after his assertion that the Sun orbits around the Earth.

Ptolemy was probably more interested in currying favor with his Roman patrons than in the truth. The Roman emperors wanted to suppress the lunar calendar and matriarchal societies, and Ptolemy cooperated with by re-arranging the Zodiac from 13 to 12 signs and renaming the female deities as men. His ephemeris deleted the most powerful female archetype of all, the snake charmer Ophiuchus.

His ephemeris failed to acknowledge the precession--the small anomaly in the Earth’s rotation, which made all his calculations degrade by an error of one degree every 72 years. This was insignificant during Ptolemy's lifetime, but has become HUGE over the centuries, and has caused bogus results in every calculation 12 sign astrologers make to this very day. Ptolemy pushed astrology and astronomy apart, which has bastardized "modern" astrology from a science to a farce.

The Romans didn't care about accuracy, they cared about slaves and making themselves richer. They used astrology to impose their rule and repress women and African philosophy. They changed astrology, eliminating the female-oriented lunar calendar. That's a clue as to why tropical, 12 sign astrology actually supports misogyny and patriarchy, and has enforced a male-supremacist view of its archetypes. This is why its so tragic that female astrologers participate in its propagation. It amounts to horizontal violence against women!

Tropical system's inaccuracies lead to more than just bad signs, it creates IMPOSSIBLE scenarios, and distorts the true nature and gender of the signs. That's why Tropical charts can't be used even to predict something so basic as the change of seasons. According to Tropical charts, the first day of spring occurs in April, as it was in Ptolemy's time, not in March as we know it today.

The Romans are responsible for the simplification of sign division as well. They sliced the Zodiac into twelve, equal 30 degree segments, rounding off the actual times of the Sun's travel. This may have been convenient for astrologers before the advent of computers, but is not applicable today. The actual cusps vary from sign to sign.

The true dates of the Sun's travel through the Zodiac

SIGN Dates of passage Days in sign Star
Virgo 16 September – 30 October 45 days Spica
Pisces 12 March – 18 April 38 days Eta Piscium
Taurus 14 May – 19 June 37 days Aldebaran
Leo 10 August – 15 September 37 days Regulus
Sagittarius 18 December – 18 January 32 32 days Kaus Australis
Gemini 20 June – 20 July 31 days Pollux
Capricornus 19 January – 15 February 28 days Deneb Algedi
Aries 19 April – 13 May 25 days Hamal
Aquarius 16 February – 11 March 24 days Sadalsuud
Libra 31 October – 22 November 23 days Zubeneschamali
Cancer 21 July – 9 August 20 days Al Tarf
Ophiuchus 30 November – 17 December 18 days Rasalhague
Scorpius 23 November – 29 November 7 days Antares

Female role models Aries, Leo and Taurus were changed to animals to further make women irrelevant. The powerful female guardian and snake goddess Ophiuchus was banished and her constellation was transmogrified into an old male Greek pretender. The persecution of women was codified in the Zodiac and their influence was reduced to only a few asteroids. The female signs were objectified: Venus the prostitute, Cancer the mother, and Pisces the slave.

The Greek and Roman assault on the Zodiac represents their dystopian view of the gods, based the premise that the female is inferior to man. This goes hand-in-hand with the Roman destruction of the mainly female leadership among Germanic, Gallic and the Celtic tribes and their enslavement of all women in the empire, including their own.

There are, and have always been 13 constellations. Ptolemy may have been considered a genius of his day, after spending years pouring over ship captain's maps stolen from the Great Library of Alexandria, (which the Romans sacked in 30 BCE), but he corrupted astrology for the next 2,000 years. Until now, when a more accurate 13-sign astrology has emerged.

Ptolemy: Fake or Fail?

The man who insisted that the Sun revolved around the Earth, Ptolemy, also fixed the equinoxes to the seasonal cycles of the 2nd century, which predictably change, and move backwards by fractions of degrees every year. He wanted to place Aries, the god of war, in first place for eternity. This was pleasing his Roman masters, but it planted a bug in his own ephemeris that has grown into a 28-35 degree error from the norm—the astronomical Zodiac. The result has been catastrophic for the credibility of astrology, which is now little more than pop culture and a rip-off revenue stream for opportunists.

What worked thousands of years ago for Roman astrologers has become a fool's errand today, distorting the planets' positions by an entire Zodiac sign, and it's growing worse every year. Ptolemy probably knew the precession would eventually throw his figures off in future generations (Hipparchus has already done the research) but he just didn't care, or did not dare contradict his Roman bosses. He changed astrology for the purposes of aggrandizing the Roman emperor, and thus Ptolemy doomed his descendants to employ false data for the next two centuries. He stuck a knife into every tropical astrologer's back. Any astrologer who still uses his system either doesn't know astronomy, or doesn't care.

Ptolemy created a faulty ephemeris, yet his work has been unquestioned and accepted as default by today's tropical astrologers, destroying its astronomical basis. Ptolemy's legacy is misinformation. To use his system is anti-science.

Ophiuchus is Back!

Medusa is one of the incarnations of Ophiuchus
[image by Hiroko Sakai]

13 Signs: By and For Women

Anyone believing--or selling--tropical astrology will be disappointed, shocked perhaps, to find the planets aren't where it says they are. The tropical ephemeris it uses is complete fiction. If it were a navigation chart for sailors, not a single ship would ever reach its destination.

Tropical astrology forces astrologers to stretch the nature of the archetype to fit the inaccuracies of the chart, which is unethical and a lot of extra work. One of the major consequences of tropical astrology is that because the fundamentals are so far off, astrologers tend to scramble around to give their patchwork interpretations the ring of truth. 12-sign astrology is a word salad, no facts.

These hapless astrologers end up simplifying or altering the meanings of the signs to fit their own empirical evidence; tropical astrologers have to second guess themselves at every turn. They are forced to equivocate to cover up the basic problem with tropical astrology, that it's completely out of date, out of whack.

Only a few astrologers use the 13-sign system. But ALL astronomers use it. On the other hand, most astrologers use the tropical system, yet NO astronomer would be caught dead using it. You can't use a system that has no roots in astronomy, because astrology was developed (and can only function) as a result of an accurate view of the planets and stars. The longer the tropical astrologers try to resist this fact, the deeper they are painting themselves into a corner. The credibility of astrology is at an all-time low.

However, all this will change. As more people discover the true astrology, our consciousness will also change, and we can use astrology as it was intended, not only as a step toward self-knowledge, but to guide us in social relations, psychology and politics, as it was originally intended to do. The future of astrology is starting now.

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Comparison of the Zodiac systems





Aries Mar 21 - April 20 April 15 - May 15 April 19 - May 13
Taurus April 21 - May 20 May 16 - June 15 May 14 - June 19
Gemini May 21 - June 20 June 16 - July 15 June 20 - July 20
Cancer June 21 - July 21 July 16 - Aug 15 July 21 - Aug 9
Leo July 22 Aug 22 Aug 16 - Sep 15 Aug 10 – Sep 15
Virgo Aug 23 - Sep 22 Sep 16 - Oct 15 Sept 16 – Oct 30
Libra Sep 23 - Oct 22 Oct 16 - Nov 15 Oct 31– Nov 22
Scorpio Oct 23 - Nov 21 Nov 16 - Dec 15 Nov 23 – Nov 29
Ophiuchus NA NA Nov 30 – Dec 17
Sagittarius Nov 22 - Dec 21 Dec 16 - Jan 14 Dec 18– Jan 18
Capricorn Dec 22 - Jan 20 Jan 15 - Feb 14 Jan 19 – Feb 15
Aquarius Jan 21 - Feb 19 Feb 15 - Mar 14 Feb 16– Mar 11
Pisces Feb 20 - Mar 20 Mar 15 - April 14 Mar 12 – April 18

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Recommended Books

[These books are for 12-sign astrology; However, aspect and transiting angles are the same in all systems.

Go to our Ophiuchus Rising page for the meanings of the angles, planets and asteroids in Ophiuchus]

Key Words for Astrology -- Paperback
by Hajo Banzhaf, Anna Haebler
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Aspects in Astrology: A Guide to Understanding Planetary Relationships in the Horoscope -- Paperback
by Sue Tompkins
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Sextrology: The Astrology of Sex and the Sexes -- Paperback By Stella Starsky, Quinn Cox
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Transits Simplified -- Paperback
by Sakoian & Acker
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Astrology of Human Relationships -- Paperback
by Frances Sakoian
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