Sidereal astrology
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Sidereal astrology is the system of astrology used by some western and all Jyotish astrologers which bases their interpretation around the use of the sidereal zodiac. It was introduced to the West by the Irish astrologer Cyril Fagan in 1944 and is practiced by a minority of Western astrologers. Its primary feature is that the signs of the zodiac align to the sky constellations of the same name. The signs therefore run between dates which are different to the tropical zodiac used in the west. For example Aries is March 21 to April 19 in the tropical zodiac but April 14 to May 14 in the Sidereal (although the precise dates may vary depanding on the Sidereal system used).
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[edit] Background
The classical zodiac of Greek astronomy as defined by Ptolemy is tropical in nature, defining the signs relative to vernal equinox regardless of the position of constellations. Western astrology traditionally uses this system.
Sidereal astrology ties its signs of the zodiac to the actual constellations.
The precession of the equinoxes, a phenomenon discovered in ca. 130 BC by Hipparchus and known to Ptolemy, results in a shift between the two systems of about one degree every 70 years.
The vernal equinox lay near the beginning of the Aries constellation around 500 BC, consistent with a Babylonian origin of the system.
While classical tropical astrology is based on the orientation of the Earth relative to the Sun and planets of the solar system, sidereal astrology deals with the position of the Earth relative to both of these as well as the stars of the celestial sphere. The actual positions of certain fixed stars as well as their constellations is an additional consideration in the horoscope. (Over very long astronomical time scales these fixed stars are of course themselves far from stationary).
Some Sidereal astrologers denounce tropical astrologers for failing to relate to the "actual heavens", seeing in this a fundamental degeneration of the subject (Kenneth Bowser, The Traditional Astrologer magazine, (Ascella), Issue 14, May 1997, pp.23-27 [1]).
[edit] Hindu astrology
Traditional Hindu astrology is sidereal, accounting for the shift of the equinoxes by a correction called ayanamsa. The difference between the Hindu and the Western zodiacs is currently around 24 degrees. This corresponds to a separation of ca. 1700 years, or roughly the centuries following Ptolemy, apparently going back to Indo-Greek transmisson of the system.
At this time, the vernal equinox was approximately at the center of the constellation Pisces.
[edit] Cyril Fagan
Cyril Fagan assumes the origin of the zodiac of 786 BC, when vernal equinox lay somewhere in mid-Aries, based on a major conjunction which occurred in that year (ref), corresponding to a difference of some 39 degrees or days.
[edit] Signs vs. astronomical constellations of the zodiac
Nearly all astrologers, tropical and sidereal, agree that the ecliptic should be divided into twelve equal segments to form the zodiac; they differ on where the zodiac begins.
Thus, most sidereal astrologers simply divide the ecliptic into 12 equal signs of 30 degrees but approximately aligned to the 12 zodiac constellations. Assuming an origin of the system in 786 BC, this results in an identical system as that of the classical tropical zodiac, shifted by 39.5 days, i.e. if in tropical astrology, Aries is taken to begin at 21 March, sidereal Aries will begin on 30 April.
[edit] The 13 astronomical constellations of the ecliptic
A small number of sidereal astrologers wish to include other constellations, such as Ophiuchus, in their zodiac and use thirteen signs instead of twelve[citation needed]. This results in a system completely unrelated to the zodiac as described by Ptolemy. While Ptolemy has of course noted that Ophiuchus is in contact with the ecliptic, he was aware that the twelve signs were just conventional names for 30 degrees segments (especially since the Aries sign had ceased to be in contact with the Aries constellation already in his time).
For the purpose of determining the constellations in contact with the ecliptic, the constellation boundaries as defined by the International Astronomical Union in 1930 are used. For example, the Sun enters the IAU boundary of Aries on April 19 at the lower right corner, a position that is still rather closer to the "body" of Pisces than of Aries. Needless to say, the IAU defined the constellation boundaries without consideration for astrological purposes.
The dates the sun passed in front of the thirteen astronomical constellations of the ecliptic in are as follows, and are accurate to the year 2002. The dates will increment by one day every 70½ years and already several have changed. The corresponding tropical and sidereal dates are given as well.
| Constellation | Tropical date | Sidereal Date | Sun is in constellation | |
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Aries | March 21 - April 19 | April 15 - May 15 | April 19 - May 13 |
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Taurus | April 20 - May 20 | May 16 - June 15 | May 14 - June 19 |
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Gemini | May 21 - June 20 | June 16 - July 15 | June 20 - July 20 |
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Cancer | June 21 - July 22 | July 16 - August 15 | July 21 - August 9 |
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Leo | July 23 - August 22 | August 16 - September 15 | August 10 - September 15 |
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Virgo | August 23 - September 22 | September 16 - October 15 | September 16 - October 30 |
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Libra | September 23 - October 22 | October 16 - November 15 | October 31 - November 22 |
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Scorpius | October 23 - November 21 | November 16 - December 15 | November 23 - November 29 |
| Ophiuchus | November 30 - December 17 | |||
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Sagittarius | November 22 - December 21 | December 16 - January 14 | December 18 - January 18 |
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Capricornus | December 22 - January 19 | January 15 - February 14 | January 19 - February 15 |
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Aquarius | January 20 - February 18 | February 15 - March 14 | February 16 - March 11 |
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Pisces | February 19 - March 20 | March 15 - April 14 | March 12 - April 18 |
[edit] The 21 zodiacal constellations of the planets
Because of their inclination from the ecliptic, the planets are not restricted to the thirteen constellations of the ecliptic. The six planets (Pluto is no longer considered a 'planet' since the term's definition change in August 2006) pass through 21 constellations. Thus there are 21 astronomical constellations of the zodiac. These are, in addition to the 13 constellations listed above, Cetus, Corvus, Crater, Hydra, Orion, Pegasus, Scutum, and Sextans.
[edit] References
- "The Real Constellations of the Zodiac". Dr. Lee T. Shapiro, Planetarian, Vol 6, #1, Spring (1977). [2]
- "The Real, Real Constellations of the Zodiac". John Mosley, Planetarian, Vol. 28, #4, December (1999).
- "The Primer of Sidereal Astrology", Cyril Fagin and Brigadier R. C. Firebrace, American Federation of Astrologers Inc., (1971) ISBN 0-86690-427-1
