Sidereal Zodiac - © Dr Shepherd Simpson

Definition: [Zodiacs] A band of the heavens approximately 14º wide, centered on the Ecliptic, against which the Sun and planets are seen to move, as seen from the Earth. This band is divided into equal 30º segments, each one of which corresponds to one of twelve Greek constellations. Each Sun sign is of equal length. The word Sidereal means, based on the stars. This is the prime difference between this description of the heavens and the other, conventional Western description of the zodiac, the Tropical Zodiac, which is based on the calendar and seasons. The vast majority of we Western astrologers don't use this zodiac - though it's better than the one we are using. Follow this link for a comparison of the Tropical and Sidereal Solar Zodiacs.

Further Information: As its based on the actual positions of the stars, the Sidereal Zodiac gives a description of the heavens which is much more realistic and accurate than the Tropical Zodiac. This is because, as the stars move with the Movement of the Ages, accurate observation of the stars can be used to redefine the positions of this zodiac to agree with reality. The Tropical Zodiac in contrast is frozen in time.

However, the Sidereal Zodiac still has problems in that it is an oversimplification of what is really 'above' us.

The first problem is that it still insists that there are twelve signs, even though in reality there are thirteen, Ophiuchus being the 10th sign of the Real Solar Zodiac.

The second problem is that it insists that the Signs are all the same length: one twelfth of a year. The heavens just aren't that tidy. The actual lengths of the signs vary from seven days for Scorpius to forty-five days for Virgo. Gemini is the only Sign whose actual size is close to one twelfth of the year.

The third problem is that the Sidereal Zodiac still insists that Aries is the first Zodiac Sign. It has lost the ancient connection with the Ages. In fact Pisces is the Sign at the Equinox and is therefore the first Sign of the year according to the Ancient definition.

Types of Sidereal Zodiac: There are two main types of Sidereal Zodiac. They differ only by their starting points, the so-called "First Point of Aries". But this causes quite a lot of debate.

In the Sidereal systems, the first, or fiducial, point can not be the Vernal Equinox, as in the Tropical Zodiac. It has to be a star in the heavens. But which one? And which part of the Zodiac does it mark? The different types of Sidereal Zodiac differ slightly in how they pick this star and which point of the Zodiac it is meant to represent. This gives a slight difference in results between themselves [and a very large difference - nearly a whole sign - between them and the Tropical Zodiac].

The Hindu word ayanamsha [or Ayanamsa] is the term applied to the angle between the start of the sidereal description of the zodiac and the Vernal Equinox - the start of the Tropical Zodiac. As the centuries go by this difference increases because of the Movement of the Ages. Perhaps the most famous [and standard] ayanamsha - at least in the West - is the Lahiri ayanamsha. Spica, the Ear of Wheat, α Virginis, is taken as the star and it is defined to lie on the zodiac at 0 degrees Libra.

Sidereal Zodiac A: 'Vedic' Zodiac: Perhaps [though Western Siderealists would dispute this] the more ancient Sidereal Zodiac is the Eastern, Vedic, Jyotish or Indian [ four names refering the same thing] Sidereal Zodiac. The 'Vedic' Zodiac is followed by more than half a billion adherents in India. [It purports to date back to the Vedas, hence the name. Though, in fact this name has only been used since the 1980s and a reading of the Vedas will reveal precious little about astrology. In contrast, the term Jyotish, meaning science of light is millennia old.] However, precisely what is the fiducial point in 'Vedic' astrology is a vexed question, as there is more than one school of thought. For example, the Chitrapaksha ayanamsha [Chitra = the star Spica] is defined by an ayanamsha of zero in the year 285 AD. In other words in 285 AD the Vernal Equinox and the start of the sign of Aries are defined to have been in exactly the same place.] Why the year 285 AD is chosen I have no idea. An example of the current dates [for a particular ayanamsha] of the 'Vedic' Zodiac is given in the table below.

Sidereal Zodiac B: Fagan Zodiac: The second Sidereal Zodiac claims to represent something even older than the Vedic system, but was either 'formulated' or 'rediscovered' [depending on which side of the discussion you take] in the last century by Cyril Fagan of the Western Siderealist school of astrologers. [See: Zodiacs Old and New: A Probe into Antiquity and What was Found, Llewellyn Publications Ltd, Los Angeles, USA, 1950.] He chose Spica, the Ear of Wheat, α Virginis, as the fiducial point [sometimes called the synetic vernal point], defining it as lying at 29 degrees Virgo in the zodiac [not 0 Libra as above in the Lahiri ayanamsha]. Fagin argued that this was in better agreement with the method used by the ancient Babylonians to describe the Zodiac.

Probably, if there was agreement on one Sidereal Zodiac this type of Zodiac would have made more of an impact in the West. However, the arguments over fiducial points have allowed us to continue using the Tropical Zodiac in the West without much opposition. [These arguments, ironically, reflect the fact that back in the times of the Classical Greeks, we astrologers couldn't agree on this issue, never mind today. See Zodiac Wheels for more on this.] This is unfortunate as the Sidereal Zodiacs are far more accurate than the Tropical Zodiac. However, as the Real Solar Zodiac is available merely from measuring the Sun's position against the actual Constellations, it does make all these arguments seem rather needless. Just as with the problems with Tropical Zodiac that we wrestle with in the West, Sidereal Astrologers seem unable to free themselves from their history - and simply use the real heavens as a guide.

The Stars and the Vedic Zodiac: Unlike the Tropical Zodiac, as the Vedic Zodiac is a Sidereal Zodiac it can include information on the astrological effects of stars themselves. It does this by means of 27 Nakshatras, each corresponding to a particular star. However, these form part of Vedic astrology in the shape of a Lunar Mansions, not a Solar Zodiac. Follow the Lunar Zodiac link for more information.

The Sidereal Solar Zodiac