reply to post by SeaWind
Lets look at the difference in Zodiacs:
The ancient “bible” of Western Astrology was the “Tetrabiblos” by mathematician, astronomer, astrologer Claudius Ptolemy (no relation to the
royal family of the last Egyptian dynasty) who lived in Hellenized Egypt from AD 90 to AD 168. He was a Roman citizen and probably an ethnic Greek.
The Astrology he founded is referred to as Greek Astrology or Graeco-Egyptian Astrology or Hellenistic Egyptian Astrology. I have seen this also
called “Egyptian Astrology” although I think this is grossly misleading since the pre-Hellenistic Egyptians (pre- 305 BC) had their own astrology
based on the fixed stars.
Claudius Ptolemy used a zodiac based on the Vernal Equinox (first day of Spring). In other words, the Aries Ingress (0 degrees Aries) was based on the
day when day and night were of equal length (this varies from one year to the next) and usually falls between the 19th and 21st of March. This is
called the Tropical Zodiac. That was fine while Ptolemy was alive.
In AD 221, the Tropical Zodiac and the Sidereal Zodiac were exactly aligned. Unfortunately for the Western astrologers, it did NOT remain so. These
two zodiacs have diverged at the rate of 1 (one) degree every 71 and a half years. And for whatever reason, the Western astrologers did NOT adjust
their Aries Ingress for the Precession of the Equinoxes.
(Most Western astrologers will defend [to the death] the validity of the Tropical Zodiac. The Tropical Zodiac has its uses in terms of anything
dependent on the seasons or weather. It should NOT be used for delineating the natal chart or predictive work.)
We cannot discuss Sidereal Zodiacs without mentioning the Ayanamsha (the Sanskrit word for the precession rate). There is more than one Sidereal
Zodiac, in fact there are several depending on which Ayanamsha you use. This is hotly debated in astrological circles. (I personally use the Lahiri
and the Fagan-Bradley.)
In 1950, the government of India decided that they would recognize the Lahiri Ayanamsha which aligns 0 degrees Libra (or exactly 180 degrees Sidereal
longitude) with the fixed star Spica (or Chitra in Sanskrit).
I also use the SVP (Synetic Vernal Point) defined by Cyril Fagan and listed in the Michelsen ephemeris. As an example, the SVP for 01 January 2011 is
5 degrees Pisces, 6 minutes and 4 seconds – which means that’s where the Sidereal Aries Ingress is. Or you could say that the Tropical 0 degrees
Aries is almost 25 degrees off from the Sidereal.
Here’s a chart to help you find your Sidereal Sun Sign (note that days can shift from one year to the next):
Aries -- Apr 14 to May 13
Taurus -- May 13 to Jun 15
Gemini -- Jun 15 to Jul 15
Cancer – Jul 15 to Aug 16
Leo – Aug 16 to Sep 16
Virgo – Sep 16 to Oct 16
Libra – Oct 16 to Nov 15
Scorpio – Nov 15 to Dec 15
Sagittarius – Dec 15 to Jan 14
Capricorn – Jan 14 to Feb 13
Aquarius – Feb 13 to Mar 13
Pisces – Mar 13 to Apr 13
edit on 15-1-2011 by SeaWind because: added spaces for clarity.