Astrology
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We are born at a given moment, in a given place and, like vintage years of wine, we have the qualities of the year and of the season of which we are born. – Carl Jung
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[edit] Definition
Astrology is the notion that the positions and motions of the stars and planets determine a person’s personality and influence the course of daily life.
[edit] Branches of Astrology
Types of astrology include
- Natal Astrology: Determination of a person’s character and fortune,
- Horary Astrology: Determining answers to questions,
- Electional Astrology: Determining the best time for an action,
- Mundane Astrology: Predicting large-scale trends and events in society and government,
- Medical Astrology: Diagnosis of medical conditions,
- Astrometeorology: Prediction of weather (using astrology).
[edit] Astrology and Astronomy
Astrology and astronomy both begin from a detailed observation of the motions of heavenly bodies.
Astronomy is the discipline which seeks a scientific understanding of celestial observations, and the mechanics behind them. Astrology, by contrast, is concerned with divination and prediction of the effects on human lives. Since astrology does not use scientific rigor and method to reach its conclusions, it considered a pseudoscience.
[edit] Basics of Western Astrology
Viewed from the Earth, the planets appear to be confined to a band of sky near the ecliptic. Along this band, tradition has recognized twelve constellations, or signs, or houses, which the planets may move through. These signs, collectively called the Zodiac are of great importance in Astrology due to the emphasis on planetary motions. (Note that the constellation called “Scorpio” in astrology is properly called “Scorpius” by astronomers, and “Capricorn” in astrology corresponds to “Capricornus”).
Relationships between planets and signs may be described in terms of the angle of separation, as viewed from the Earth. The following types of separation, called aspects are especially portentous:
- Conjunction: minimal separation
- Opposition: separation of nearly 180°
- Syzygy (or alignment): Conjunction or Opposition
- Quartile (or square) separation of nearly 90°
- Trine separation of nearly 120°
- Sextile (or hexagon) separation of nearly 60°
A person’s sun-sign is the sign that the sun was in at the moment of their birth. Less important are a person’s moon-sign and various planet signs. The exact time of birth may also be used to determine the positions of these planets in the sky.
An astrological prediction or horoscope can then be constructed based on
- The positions of the planets relative to each other,
- The positions of the planets relative to a person’s sun-sign,
- The positions of the planets within each sign.
These can be interpreted in the context of the supposed character of the planet, the character of the sign, and the characters of the aspects.
[edit] Famous Modern Astrologers
- Sydney Omarr (1926-2003), wrote books on astrology which popularized the now common “sun-sign astrology”. He wrote a syndicated newspaper horoscope, and advised various celebrities.
- Joan Quigley (1927- ) achieved fame (or infamy) as an astrological consultant to American First Lady Nancy Reagan. Through Mrs. Reagan, Quigley greatly influenced the President’s daily schedules.
- Jeane Dixon (1904-1997) supposedly predicted in 1956 the assassination of President Kennedy. While it is true that she predicted an assassination attempt for the next president, she also predicted later in 1960 that Kennedy would lose the election. She also predicted that World War III would begin in 1958, and that the Soviet Union would put the first man on the moon. Mathematician John Allen Paulos coined the term “The Jeane Dixon Effect” to describe the selective memory responsible for her perceived accuracy.[1]
[edit] Origins and History
To prehistoric people, it would have been immediately obvious that the daily motions of the sun were linked to the sleep-and-wakefulness cycles in animals and humans. Great significance could also be attached to the motions of the moon, which affected hunting and fishing activities, and to the yearly declination of the sun, which affected the growing of crops and wild plants. As agriculture became more developed, the question of when to begin large-scale planting or harvesting operations could be answered adequately by observing the stars.
The prediction of seasons was literally a matter of life and death for ancient cultures. It is no surprise then, that eventually the motions of all heavenly bodies were anxiously studied, and assumed to have some effect on terrestrial activities.
The apparent motion of the planets across the background of stars presented two problems to ancient astronomers. First, it was somewhat erratic, compared to the even cycles of the sun, moon, and stars. Secondly, it did not have any obvious application. The motions of the planets, then, were considered representative of the apparent chaos of to earthly life.
Western astrology has its roots in the ancient Babylonian practice, in which the erratic motions of the planets were identified with capricious deities. The Babylonian system ultimately led to the 12 signs commonly recognized today. At this time, astrology was mainly confined to "mundane astrology", used to predict the fortunes of kings and empires, not the day-to-day concerns of the masses.
From the beginning, astrology encompassed two separate activities: observation and prediction of heavenly movements, and divination based on those findings. The first eventually became the modern discipline of astronomy, while the second was reduced to the pseudoscience of astrology.
Babylonian astrology was adopted by the ancient Greeks, who perfected most of the techniques used today, and introduced the common natal astrology found today. Medieval European astrology developed a system in which the planets were correlated with the elements of alchemy, and the organs of the human body, among other things.
The renaissance brought the modern understanding of celestial mechanics, begun by Tycho Brahe and Johannes Kepler, and placed on a physical foundation by Isaac Newton. It offers no mechanism by which planetary motions can effect or portend daily events on Earth.
[edit] Supposed mechanisms
Astrology does not promote any plausible theory concerning the means by which the planets may affect life on Earth. However a few supposed mechanisms are occasionally proposed:
[edit] Gravity
The force of Gravity is one obvious mechanism, since it is known that the force of gravity extends indefinitely from the mass. Thus, it seems reasonable that, say, Saturn could gravitationally affect terrestrial objects.
The problem with this claim is that gravity diminishes greatly with distance, making the influences of other planets negligible in this regard. It has been pointed out that the gravitational influence of the people in the delivery room of a hospital is greater than that of Saturn, yet astrology is not concerned with the placement of people attending the birth. In fact, the change in the Earth’s gravity based on which floor of the hospital a birth takes place on is far greater than the influence of Saturn.
[edit] Tidal Forces
Astrologers will point out that the Sun and the Moon have a tremendous effect on the Earth’s tides, dramatically altering the shape of the world’s oceans on a daily basis. Is it not plausible that it would have a similar effect on water-based creatures such as we?
The “tidal force” of the moon is essentially a product of the difference in the Moon’s gravity between the near and far side of the Earth, the far side being 8000 miles further than the near side. This difference is so slight, that it only suffices to change the shape of the hydrosphere by a few meters. On objects of the scale of human beings, this difference is negligible, and we feel no “stretching” force due to the tidal effects of the Moon and Sun.
There is, in fact, some evidence that tidal forces are felt indirectly through changes to the Earth’s magnetic field. [2]
[edit] Skeptical arguments
- I don't believe in astrology; I'm a Sagittarius and we're skeptical. – Arthur C. Clarke
Astrology is considered a pseudoscience, since it claims scientific provenance, but does not adhere to scientific method or principles.
[edit] Falsifiability
The first objection to astrology, from a scientific point of view, is that its predictions are often too vague to be testable, and thus it is unfalsifiable. The ultimate result of the practice of astrology is often a vague prediction which, after the fact, can be shoehorned into any event that happens to occur. Consider the horoscope from astrology.com[3], for the sun-sign of Aquarius, on September 12, 2005:
- Working together with a certain colleague seems like a recipe for disaster, but if you restrict yourself to tackling the task at hand, you might just get more done than you'd originally hoped for. Keep that nose to the grindstone.
It may be noted that “if you restrict yourself to tackling the task at hand, you might just get more done than you'd originally hoped for” is probably true for any sun-sign, on any day. “Working together with a certain colleague seems like a recipe for disaster” is vague enough that anyone at all can identify a “certain colleague” that matches the prediction.
[edit] Precession
One result of this is that the sun-signs assigned to individuals based on their birth date do not reflect the actual constellation the sun is found in. For example, a person born on February 1 has the sun-sign of “Aquarius”, even though the sun is squarely within Capricornus at that time.
Another effect of precession is that the ecliptic now intersects the constellation Ophiuchus, not included in the zodiac.[4]
It should be noted that modern Hindu astrology uses current star and planet positions in its practice.
[edit] Contradictory Predictions
A major criticism of astrology is that two different practitioners may make completely different predictions. It is a hallmark of scientific theory that predictions do not depend on individual bias or opinion. This emphasizes that astrology does not advance any formal theory. Consider the following two horoscopes for Aquarius, on September 12, 2005:
From the Sacramento Bee:
- Unstructured activities are apt to be the ones you'll find the most enjoyable today so be flexible and responsive to the suggestions of others. Traveling, studying, doing research, and most of your mental and manual aptitudes are favored this morning. You are rather creative in the work you do.
From the Los Angeles Times:
- The power of friendly connections is highlighted -- but for you, when isn't it? A business proposition between pals is intriguing. Success is inevitable if basic principles are agreed upon in advance.
One prediction suggests “unstructured activities”, while the other stresses “business propositions” and “agreement on basic principles”. Which is correct? And if one is inaccurate, why not both?
[edit] Lives of Twins
One way that astrology may be challenged is to consider the lives of twins, who, born minutes apart, presumably have the exact same planets in the same signs at the time of their birth. Yet twins often end up living lives as varied as non-twin siblings, and experience different fortunes. Indeed, there are certainly cases of one twin dying in infancy while the other goes on to live a long life. If astrology makes no distinction between the twins in terms of their birth signs, then it cannot make different predictions for them. If it cannot predict such profoundly different fates for two individuals, then it is worthless, or at least, constrained to the more trivial details of life.
[edit] New Planets
The planets Uranus and Neptune, unknown to ancient astrologers, were discovered in the 18th and 19th centuries, respectively. Today they are regularly included as a factor in determining astrological horoscopes. This raises the question: if all astrological horoscopes prior to the 18th century neglected these two important planets, why was astrology thought to be so accurate at the time? And how have subsequent predictions been any better, neglecting such new discoveries as Ceres, Pluto, and Sedna? How can we trust that the current predictions are finally based on a complete model of the Solar System?
What particularly distinguishes astronomy from astrology was the manner of the discovery of Neptune itself. Slight deviations from the expected orbit of Uranus could only be explained under the current understanding of celestial mechanics, by supposing that another enormous planet was present. Using mathematics and physics, Urbain de Verrier predicted the exact spot where the planet ought to be, and Johann Galle sighted it within one day.
Had astrology been a rigorous, formal, and theoretically-based enterprise, we might imagine a similar scenario: astrologers would notice that their predictions were not quite accurate, and to explain the discrepancy, it would be necessary to suppose a new planet. The position of the planet could be determined by finding what position would make the predictions more harmonious with observed effects. And, voila, the planet would be there. Such a scenario, of course, never occurred.
[edit] Constellations
Finally, it should be noted that the signs of the zodiac, and indeed, the constellations recognized by astronomers, are entirely arbitrary, human constructs. There is not necessarily any relationship between stars in a particular constellation, except that they just happened to resemble something. The constellations are useful as mnemonic devices, and for the purposes of identification, but scientific theories ascribe no significance whatsoever to these groupings.
[edit] Experiment: Identify Your Horoscope
A simple experiment can test the accuracy of astrological predictions. Don’t read your horoscope for an entire day. At the end of the day, have a friend read the horoscopes from a trusted source, in random order. Try to identify which prediction most accurately described the events of the day. This can be repeated over several days.
If horoscopes are accurate, then you should be able to identify which horoscope was intended for you. If they are even slightly accurate, then you should be able to identify your horoscope, say, one sixth of the time.
It is important when testing the accuracy of the predictions, not to identify which horoscope is “yours”; as this may unduly influence your judgment.
[edit] References and Further Reading
- Glossary of astrological terms
- History of the Zodiac
- Stellarium: Free, open-source astronomy software (source for above images)
