Archive for January, 2014

Astrology – the ancient divination

January 31, 2014 5 comments

Astrology is a part of the cultural baggage many Indians, especially those from Hindu background, carry around since childhood. It is ingrained into Indian society so deep that there are numerous institutes that exclusively teach astrology; Horoscope and astrological compatibility are essential parameters to make or break marriages, across religions. If we take general public opinion about astrology into consideration, a significant portion comes into either having a blind faith in astrology, sometimes in a specific ‘family’ astrologer, or a benign respect and sacredness for this ancient divination technique, or that we are too simple-minded to understand the complexities involved in it. However, we can examine the framework behind the theory of astrology and its prediction model to evaluate whether it is a valid theory, or something that needs to be or can be improved, or plain nonsense.

According to Britain’s Faculty of Astrological studies, astrology “explores the meaningful connection between mankind and the wider cosmos, the relationship between the movements of the planets and the inner world of human consciousness and motivation”. So, astrology tries to look at sky, check the position of certain planets and stars, estimate their positions in the past and future depending on the situation, and predict your career, marriage life, health and financial situation.

A skeptical eye will immediately catch 2 problems with this qualitative framework of astrology as a scientific study:

Causality of the model

Astrology assumes a causal relationship between position of stars and human affairs. For example, Mars in a certain constellation predicts that you to fight with your spouse or even may cause your in-laws to die. Such predictions are not possible when there is no causality, or a connection.  So, if there is a theoretically possible way for a prediction, such a force has to exist.

The following table shows the fundamental forces of nature we have discovered till date, along with their relative strength and range:


Relative strength

Range (m)

Strong nuclear force 1038 10−15
Electromagnetic force 1036
Weak nuclear force 1025 10−18
Gravity 1

Shortly put, these forces can be explained as follows:

  • Gravity: Long range and the weakest force. Exerted by virtue of a body’s mass. It acts on all particles.
  • Weak nuclear force: Short range force responsible for radioactivity. Exerted by and acted on subatomic particles.
  • Electromagnetic force: Long range force. Exerted by electric fields.
  • Strong nuclear force: Extremely short range and the strongest force responsible for binding particles inside atomic nucleus. Exerted by and acted on subatomic particles.

The strong and weak nuclear forces are significant only at sub-atomic distances, and are not applicable at macroscopic scales. The electromagnetic force, though a long-range force, follows an inverse square law with distance, i.e., the strength of force is inversely proportional to square of distance between the particles. It becomes negligible even at a modest range, and doesn’t act in an astronomical distance. Next comes gravity, the weakest force which also follows an inverse square law. The gravitational effects of planets on humans living on earth are negligible as well.

Fun fact: The gravitational force exerted by Mars on a 100 kg person at rest on Earth comes to 0.0000000846185 Newton, which takes 15 days for the person to move by 1 centimeter. In short, it is highly negligible.

Point to be noted is that none of these forces can be responsible for effects claimed by astrology, i.e., an effect where position of planets influencing human social affairs. However, such a mysterious force should be long-ranged like gravity, very strong which cannot be shielded, effecting every person in a different way. Also, this force should be exerted only by Mars (Kuja/Mangala), Jupiter (Guru), Mercury (Budha), Venus (Shukra), Saturn (Shani), Sun (Surya), Moon (Chandra), and this force shouldn’t be exerted by the other planets like Uranus and Neptune, or the asteroid belt between Mars and Jupiter, or Jupiter’s moons, or Saturn’s moons, or the 150 other moons in Solar system and the numerous other celestial bodies. Weirdly, Lunar nodes (Rahu and Kethu), or the points of intersection of paths of Sun and Moon, also should exert this force.

Astrologers claim that this long-range, super-strong, selectively influencing force cannot be detected. If there is a force and it cannot be detected in any way, form or shape, it is safe to say that it cannot influence anything. Whatever mysterious force this is, it is not backed up by current knowledge and research, and it certainly is supernatural. There goes the claim “Astrology is science”.

Now the second problem with the framework of astrology is:

Position of planets and stars

The only part about astrology that is based on observations is calculating position of planets and constellations. This was developed by the Babylonians (2000 BCE), and was adapted by other civilizations (including Vedic astrology). The calculation model is a numerical model, based on the then observations, and Babylonians had no idea that gravity was responsible for planetary movements and how it works, and general relativity was unimaginable. This model hasn’t been revised for changing observations anytime later, as the case with practice of pseudoscience, and astrologers today use pretty much the same system.

The problem here is that the observations made 4000 years back were not correct: We can know this by our current knowledge. Since there was no idea about precession of earth’s axis, there are huge margins of error when we verify these calculations with current observations.

Moreover, it was thought that sky was a dome, with sun, moon and constellations lying on a flat plane. This is not correct, and when an astrologer says “Sun is in the constellation of Virgo”, it is wrong. The Sun is not actually in the constellation: It is that when we look from earth, it is the apparent position of Sun which lies on the same plane as Virgo, but they are actually hundreds of light years apart from each other.

Apparent position of Sun in a constellation, and the actual position of Sun

Apparent position of Sun in a constellation, and the actual position of Sun

On a careful inspection of the calculation model of astrology, it can be understood that “Astrology is bad astronomy, if not astronomy”.

Efficacy of predictions

Since there is no mechanism of explaining the effect of planets on humans, the only way to look at astrology is from the efficacy of its predictions, which can be empirically studied. However, to validate something like “Astrology works”, there are some problems with the nature of predictions astrology makes.

Vagueness of predictions

Predictions made by astrologers are widely vague. Let’s look at this week’s horoscope for Gemini from

“Your morale is likely to dip this week, predicts Ganesha, owing to the fact that your ability to analyse things may lose its usual sharpness. Also, your communication abilities will take a beating, as you may not be able to convey your thoughts properly, and people around you are consequently likely to misunderstand you and your motives. Ganesha therefore advises you to speak less, and let your work do the talking. You should also postpone the signing of any new contracts or deals till a little later when the stars are more favourable for you. Whether you are a professional or a businessman, work shall be too hectic and may leave you fatigued, which will take a huge toll on your health, so make sure that you take small breaks whenever possible. Don’t be reckless with your money, but try to save as much as possible.”

Is there anything specific about this prediction? In fact, it is trying to give some advise on what to do, what not to do, and even that is not specific. Do we need an astrologer to tell us to take breaks, save money, emphasize on work than talk, and sharpen abilities? Also, this horoscope reading for Gemini applies to anyone working in a moderately hectic job. If we thinks this prediction is tailor-made for us, it’s likely due to Forer effect.

The other problem with testing astrology is,

Predictive value

Astrology lacks a reliable source of predictions and statements, and astrologers often predict based on naturalistic guesswork. For eg., anyone can predict that Congress is going to lose the upcoming general elections, and that BJP would form Government with a decent estimate of number of seats, based on the ongoing political scenario and exit-polls. Astrologers themselves don’t reveal which predictions are specifically done based on astrology and which is naturalistic guesswork. Also, astrologers have a chronic habit of ignoring their missed predictions and highlighting only the successful ones. This idea of “astrology works except for the times it doesn’t” reflect a poor predictive value in the practice.

Nevertheless, studies have been done to examine whether astrological predictions are more significant than guesswork. Typical studies involve asking astrologers to match birth charts with the subject’s history, photographs, and other personal details. Other studies involving matching birth-charts to personalities were also conducted. These controlled studies that tested whether astrologers can do what they say can do concluded that they can do no better than chance.

Astrology, basically, to strip away with fashionable articulation, claims that huge balls of rocks, liquids, gases, and nuclear fusion reactions millions or billions of miles away from Earth can affect the financial, sexual, emotional, and employment situations of individual carbon-based life forms on one specific planet. This claim has been thoroughly demonstrated to be implausible and ineffective. However, to cut astrology some slack, it has acted as a protoscience, which is a field of study before modern scientific method was established, and provided foundation for modern astronomy. After all that time spent in gazing the sky, some useful information has slipped into human knowledge.

In conclusion, astronomy, if anything, is not a scientific study, and has no basis in the current scientific method, and doesn’t comply with our existing knowledge of the nature. In recent times, it is being marketed more as a solution for people in their social and personal problems, under a veil of science, and the practice has become a sham, suggesting remedies and ripping people of their time and hard-earned money.

References and some studies on astrology:

“Astrology”. n.d. In Wikipedia. from <

“Pseudoscience in the stars”. In Nirmukta. from <

A scientific inquiry into the validity of astrology, Journal of Scientific Exploration. Vol. 4, No. I, pp. 75-83, 1990

“An Indian test of Indian astrology”. In Skeptical Inquirer. from <

“Skeptical studies in astrology”. In Psychic Investigator. from<

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