Yesterday I watched an interview with an astrologer on a network that purports to deliver news. For wholly incomprehensible reasons, the interviewer chose to ask an astrologer about NASA’s designation of a “new constellation of the Zodiac”. Actually, the designation of the boundaries of constellations is the work of a committee charged with nomenclatural issues, and has no physical significance. Decades ago the sprawling constellation Serpens (the Serpent) was subdivided for purely practical reasons into Serpens Caput (the Serpent’s Head), Ophiuchus (the Serpent Handler) and Serpens Cauda (the Serpent’s Tail). Incredibly, the interview dwelt on the entirely specious issue of whether this changed people’s horoscopes, not with the actual story. Both the interviewee and interviewer demonstrated their level of understanding by admitting that they couldn’t even pronounce Ophiuchus.
Here’s my slant on the subject. Astrology purports that the positions of the planets against the background of “fixed” stars exerts a significant influence on people. Astronomers purport that the positions of the planets reflect precise quantitative laws. For planet-sized bodies, gravitation is by far the dominating effect. Both systems claim to have predictive and descriptive power.
Thus use of the Law of Universal Gravitation in its relativistic formulation permits extremely precise calculations of the paths of the planets through the sky, so precise that encounters of spacecraft with other planets can be planned and predicted with a precision on the order of one second after years of flight. Astronomers, using the laws of gravitation and precise observations, can detect tiny perturbations of the orbits of known planets by unknown planets (or, in the case of planetary systems of other stars, of visible stars by their unseen planets) and deduce the presence of these previously unknown bodies. Uranus was discovered by accident as a result of systematic observations by astronomers. Neptune, Pluto, and several hundred planets of other stars have been discovered by means of calculated disturbances of the orbits of nearby bodies.
Now, if the positions of the planets have influences on human affairs, periodic patterns must be present in human events. Astrology, by the simple means of identifying cyclic patters in human events, should be able to determine the existence, synodic period, and influence of hitherto unknown planets. But any such behavioral perturbations remained unnoticed. Astrology was completely ignorant of the existence of Uranus until it was discovered by astronomers. They remained completely ignorant of the existence of Neptune until it was discovered by astronomers because of its gravitational effects on Uranus, and were similarly ignorant of the very existence of Pluto until an astronomer discovered it. Astrologers can make no claims about planets of other stars, but astronomers can point to over 500 discoveries of exoplanets.
If the human influences of the planets are important, how is it that not a single planet has ever been predicted or discovered by astrologers? Clearly, astrology has no predictive power.