How dramatic have the constellation movements been?

I know astrology=/=astronomy, but this question is a fairly fine line.





Ive read that the reason Ophiuchus is being counted as the 13th astrological sign is because the vernal equinox has shifted over the years and drifted from Aries. Depending on how dramatically it shifted, would it not change the dates by the year? Whether Ophiuchus is there in the dates or not, it would seem the equinox shift would change the dates every year.|||No That's some bad science there|||Ophiuchus is sometimes called the 13th zodiac constellation because the ecliptic crosses part of it. But the astrological houses are only loosely associated with the astronomical constellations. It is true that precession of the equinoxes has moved the vernal equinox, also called the first point in Aries, out of Aries, but our calendar, the Gregorian calendar, is designed to keep the dates of the equinoxes the same, by means of the leap year rules, no matter what constellations they occupy over the centuries.|||It's rather moot. Western astrology uses a tropical zodiac (which divides the sky up into twelve equal slices), rather than the actual positions of the constellations. Despite Ophiuchus' position upon the ecliptic, you won't be seeing it appear as a sign in your local newspaper's horoscope.



Eastern forms sometimes use the sidereal zodiac, and recalibrate from year to year to adjust for such factors as precession.|||The constellations themselves are not shifting, but rather the Earth's orbit is gradually shifting. This is a very slow process, a 26.000 year cycle, which astronomers correct for a little bit each year, and update their star atlases every 50 years or so. The problem with astrology is that they have totally ignored this process for thousands of years, with the result that the constellations of the ecliptic/zodiac have shifted almost three whole constellations between the astrologer's "sky" and the real sky.





The question of Ophiuchus is a totally different issue. Ophiuchus has been a constellation recognized by astronomers for thousands of years. It has always extended down to cross the ecliptic/zodiac, but astrologers simply ignored that as inconvenient. Now some astrologers have "discovered" Ophiuchus and are trying to make their crazy structure adapt to this "new" constellation.





The best thing to do is to just ignore all astrologers,. since there really is no connection between the positions of the stars and planets, and human behaviour and personality. We now have a much better science, psychology, to address these issues, one based on observation and theory.





If you want to know just how dangerous astrology can be, read the excellent article by Phil Plait below.|||consider that the tropic of cancer is named because, at the time, the sun was in cancer at the june solstice. now it's in taurus.





astrology is nonsense. including ophiuchus doesn't change that.