Astrology and Precession

John Jackson — Tue, 06 Jan 2009 09:29:33 +0000

Let’s assume for a minute that astrology actually works. No questions, it just does. Now, when the astrological signs were drawn up originally, it was done around 600BC. Each sign (e.g.: Scorpio) are exactly 30° wide – they are measured eastward along the ecliptic from the vernal equinox, which is the intersection of the elliptic and the celestial equator and is the zero point.

When the system was originally set up, the zero point was in Aries and was called the “first point of Aries”.

Aries encompassed the first 30° of the ecliptic, next came Taurus (30° to 60°), Gemini (60° to 90°) and so on…

This scheme ignored the actual stars themselves, but uniformity was more important than fussing about star positions.

Since then, precession has caused the celestial equator to wobble so as to cause the intersection point between it and the ecliptic to move westward along the ecliptic by 36° or a tenth of the way around.

Your birth sign ignores the effect of precession. What a horoscope calls “Aries” is the 30° segment along the ecliptic that is east of the current location of the vernal equinox – but today, most of it is in Pisces. The next 30° segment (called Taurus in the horoscope) is mostly in Aries. The astrological signs are directions in space that no longer correspond to the constellations that bear their names.

Precession causes the position of the sun on the vernal equinox to move as the earth wobbles on its axis – then again, the position of the sun varies on every date (analemma). This means that it is not only the names of the zodiac signs that are now wrong, the names of the tropics are also inaccurate!

This all dates to when the sun is within the constellation of your birth sign. According to astrology (corrected for precession – although these dates will vary slightly from year to year), you may find that you’re actually a different birth sign.

If you were born between November 30th and December 17th, you’re actually an Ophiuchus.

What happens in astrology is that the sun travels through the traditional 12 signs of the zodiac over the course of the year. Whatever sign the sun is in when you’re born is the sign you “are”. However, over the past 2,600 years (since the charts were drawn up), the precession of the earth has shifted the ecliptic westwards and now the sun visits the constellation of Ophiuchus during November/December. I very much doubt you’ll find a horoscope that takes this into account.

Capricorn: January 20th to February 16th
Aquarius: February 17th to March 11th
Pisces: March 12th to April 18th
Aries: April 19th to May 13th
Taurus: May 14th to June 21st
Gemini: June 22nd to July 20th
Cancer: July 21st to August 10th
Leo: August 11th to September 16th
Virgo: September 17th to October 30th
Libra: October 31st to November 23rd
Scorpio: November 24th to November 29th
Ophiuchus: November 30th to December 17th
Sagittarius: December 18th to January 19th

Since I’m no longer Cancer and am now Gemini “all of a sudden”, does this mean I’ll have to change my character and I can sue astrologers for giving me wrong information?

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Astrology and Precession