That title probably goes without saying for the bulk of my readers, but hey, some people get here by search engines.
There are many reasons why astrology is bullshit:
I’m only going to deal with the last one for now because it is the astronomy that is the pillar of astrology. Astrology is based on the positions of stars and planets, so it’s fair to say that if the astrologer doesn’t understand the positions of the stars and planets, then the whole basis of astrology must be incorrect.
If your birthday is today, you would fall into the sign Gemini. This is your sun sign – the astrological position of the sun in the zodiac.
Except there is a problem. A huge problem, in fact… The sun is in Taurus. In fact, it won’t enter Gemini for a week or more. Oops. If you’re born a week from now, your sign will be Cancer, but the sun will be in Gemini. The reality is that the sun lags your sign by a full month. See for yourself here.
Why is that?
Because the dirt-farming ancients that made up astrology 2000 years ago didn’t know about something called precession. Our planet spins on its axis, but that axis wobbles like a top that is going to fall over (there is a nice picture on that precession link).
It traces a circle through the sky that takes about 26000 years to complete. In the time since astrological charts were first set, the whole planet has precessed about 1/12 the way around that circle – thus, the charts disagree with reality by 1/12, or one sign.
Although it’s hard to detect over the course of a human lifetime, precession does change the stars in a measurable way, although you’d have to go out of your way to notice. The celestial North Pole has moved closer to Polaris (the North Star) by about half a degree between my earliest memories of looking at the stars (1970ish) and today. How much is that? It’s about the diameter of the full moon in the sky. You don’t have to believe what I write here either. This is easily shown in any decent sky mapping software. If you took a picture from my yard (which faces north) on 16 June 1970, and one tonight, you would see that the houses remained the same but the trees had grown and the stars had all shifted by about 1 lunar diameter. How cool is that?
Of course, other aspects of astrology bullshit that are also important… when the charts were set, they didn’t know about Uranus and Neptune. Some of what we now call asteroids or dwarf planets (like Ceres) were included, but they’ve been dropped out over time… I guess their “influence” wears off? And what of poor Pluto? And what of the 500ish exoplanets? Astrologers kind of cough and change the subject when that comes up.
The only astronomical bodies that have any substantial effects on the Earth and its life are, in this order:
It may surprise you to note that even all the planets lining up produce a completely negligible effect due to gravity that is grossly overshadowed by the monthly variations due to the moon and sun. Though smaller, the moon is much closer, and gravity being an r-squared force is seriously more powerful from the moon than any planet. The sun, though far away, is immense. The rest of the planets don’t add up to diddly-squat.
All those effects are measurable and the mechanisms are well known… Unlike astrology.