Monday, January 14, 2013

Popular myths and misconceptions and the plain truth behind them – Some examples from everyday life

The great enemy of truth is very often not the lie, deliberate, contrived and dishonest; but the myth, persistent, persuasive and unrealistic.  Too often (…) we enjoy the comfort of opinion without the discomfort of thought.
John F Kennedy


I and two other fellow academicians had spent Doomsday [See my earlier blog post: 60) Waiting for the world to end – What will (not) happen on 21st December 2012 (Dec 12)] on an official visit to an educational institution in Kanyakumari district of Tamilnadu where we had spent most of the day at work indoors, occasionally peering out and checking to see if the earth was still intact… and it was!  By all predictions of the doomsayers mother Earth ought to have come to a cataclysmic end that day but disappointed them all by refusing to budge even an inch.

The incident that spurred me to write this blog post happened in a casual manner on the following day.  The conversation among a group of us somehow veered to one of the wonders of the world, the Great Wall of China, when I made an off-the-cuff remark that I had climbed and walked along it three years ago.  One of my fellow academicians, who has an exceptionally fine and spontaneous sense of humor, asked me if I had walked along all of it.  Realizing what he implied (the Great Wall is well over 8,000 km long) my other fellow academician made the remark that I had heard any number of times before, mostly from people of similar backgrounds – that the Wall is the only physical structure on the earth’s surface that is visible from the Moon.  I spontaneously told him that it was certainly not true and was just one of those popular myths.  Before I could elaborate on this, the conversation suddenly changed track, but I had decided to write about this and a random sample of several other popular myths and misconceptions in my blog very soon.  Here is what I had promised myself.

The Great Wall from the Moon myth

It is not very clear when and how this myth took root but it is so widespread among all categories of people (I don’t know what fraction of such population is Chinese) as to have become a sort of truism.  People who accept it don’t ponder to question how any construction no more than about ten meters wide, however long it may be, and blending with the surroundings almost everywhere along its length, can be visible to the naked eye from as far away as four hundred thousand kilometers.  The human eye is indeed a remarkably adaptive and versatile sensor, still the small aperture of its pupil (only about 8 mm in diameter) means a very low light gathering power, and hence the inability to make out fine detail in distant objects.
One person to whom I put this question argued that the Wall could have been visible from such a distance through a telescope.  Apart from the obvious fact that such a telescope has to be quite big, he was speechless when I pointed out that no telescope has ever been placed on the Moon or in space at comparable distances, let alone anybody looking through it.

Here is what former NASA astronaut Jeffrey Hoffman, who flew on five space shuttle missions, says about this myth: “I have spent a lot of time looking at the Earth from space, including numerous flights over China, and never saw the Wall.”  When I made a casual reference to this question in one of my travelogues on China [See: 04) China Diary Part 1 – The Great Wall & Forbidden City (Mar 10)], this is what I had to say: “Contrary to popular belief, it is not visible to the unaided eye even from any earth satellite, let alone from the Moon.”

Bloated Sun & Moon – the Moon Illusion

I wonder if anyone has not seen the Sun or the full Moon appear much bigger at the time of sunset or sunrise (or moonset or moonrise as the case may be) than it normally is.  Since it happens invariably if the horizon is clear, one cannot fail to have seen the phenomenon at least during evening sunset.  From certain vantage points and depending on the nature and type of terrestrial objects in the field of view, the sight can be spectacularly awesome, especially the rising full Moon pockmarked with its visible features as the following picture suggests.  Not only do the Sun and the Moon but also any stellar constellation appears to be blown out of proportion at such times, while resuming normalcy at others.  I pose this question frequently to groups of students and teachers, many of them from elite urban institutions, when I address them on astronomical topics.  I am yet to find anyone unaware of the phenomenon, but the overwhelming majority of them simply don’t know why.

One very common and rather vague answer I get is that some refraction effects are responsible.  When I probe into this deeper and ask for a detailed explanation, they get into a hopeless tangle and end up in a mess.  I have seen two or three Ph Ds in physics do this!  When I said the observation is just an optical illusion (often called the Moon Illusion) and had no physical basis whatsoever, at least one of them was utterly confounded and totally unwilling to accept this explanation.  He said there must be some physical reason, perhaps not yet discovered!  I wonder if they are convinced even now that there is really none.

The most common as well as the most bizarre answer I get is that objects at the horizon are closer to the earth than when they are elsewhere!  – why else would they look bigger?  In their minds the apparent paths of the Sun and the Moon (as well as the constellations) around the earth are such as to bring the object closest to the earth twice a day and keep them farther away the rest of the day. Considering how big the objects seem to appear on the horizon, this change in distance should be quite considerable.  If so why are the mornings and evenings not much hotter than the rest of the day?  This reasoning not only runs counter to all common sense but also contradicts all observational evidence.  Within a span of about 6 hours between high noon and sunset, the Earth would have hardly changed its distance from the Sun as astronomical measurements show.  Such changes are noticeable only over a period of months or at least weeks and even then not significant enough to explain the observations.

How can we show that this whole phenomenon is an illusion, just a trick played on our minds?  The best way would be to take pictures of the Sun (through a small telescope using safe filters) or the full Moon with a camera at regular intervals over several hours without changing the instrumental settings other than exposure times.  A composite picture will show a series of images whose size remains exactly the same all through.  Can there be anything more convincing?  Here is such a picture:

Once we realize that there is no physical basis for the ‘Moon Illusion’ the explanation is outside the realm of traditional science and has to look into psychological factors, especially those related to human perception.  I shall only refer readers to a lengthy article on this phenomenon discussed at:

Hot summers and cool winters

As everyone has experienced, summer days are significantly hotter than winter days almost anywhere on earth. Why is this so?  Very simple, according to most people!  The Sun gets closer to the earth in summer than in winter.  This is simply not true and often it is just the opposite.  For example, even as I write these sentences the Sun is at one of its closest approaches to the earth and still the whole of north India is shivering!  So it has hardly anything to do with the distance between the two objects.  The real reason is that because the earth’s axis of rotation is inclined at an angle of 23.5 degrees to the ecliptic (plane of the apparent path of the earth around the Sun), any point on the northern hemisphere of the earth receives sunlight at a steeper angle than a similar point in the southern hemisphere and therefore the overall energy density of solar radiation is significantly lower as the following illustration shows:

The Big Myth about the Big Temple

After reading my travelogue on the Big Temple of Thanjavur [See: 56) The Big Temple of Thanjavur a glorious heritage – Personal Photo Album Part 17 (Sep 12)] one of my regular readers appeared to have been surprised that I had made no reference to the widely popular and glaringly unscientific myth that the shadow of the great pyramidal temple tower (vimanam) never falls on the ground. Referring to this myth in a newspaper story at, a research scholar wrote, It is a falsehood repeatedly told to students, historians, tourists and all visiting the temple, which has been declared as world heritage by the United Nations Educational, Scientific and Scientific Organization''.  To prove the obvious fallacy of this he has published a photograph showing a shadow of the structure on the ground.  The moot question is does such an outrageous claim, flying in the face of all common sense, require any kind of contradictory ‘proof’ at all, even a photographic one.  How can anyone even entertain such a claim?  If there is any object standing on the ground under a bright Sun, how can there be no shadow of it cast on the ground?  I don’t know of any law of nature that exempts any temple structure from casting shadows on the ground.  It is almost as absurd as saying that the temple tower is invisible for that is the only way it cannot cast a shadow.

Myths and irrational beliefs associated with temples are so numerous and so widespread that they merit a separate psychological study.  I shall not attempt it here even in respect of this big myth about the Big Temple of Thanjavur.

When Lightning Strikes

Among natural phenomena, lightning is both amazingly beautiful to watch and deadly dangerous to experience.  It is a massive discharge of high voltage electricity in the atmosphere and can cause serious physical injury or death if one is caught unprotected during thunderstorms that are often accompanied by lightning strikes of varying severity.  Travelers outdoors in their cars or other vehicles often tend to rush out instinctively towards covered places or large trees for protection.  This is the result of a misconception that outdoor structures provide a better protection than inside a vehicle like a car.  In actual fact the greatest protection they get is by staying put inside their vehicles with all doors closed.  This is because of a well-known property of electric charges discovered by the great nineteenth century British scientist Michael Faraday.

Being inside a car during a lightning strike is like being inside a fully enclosed protective metal cage called the Faraday cage. The electrical charges induced by the lightning on the cage are confined to the metal surface and flow around it and then into the ground without penetrating inside.  The occupants are perfectly safe even if what they see outside may be highly unnerving.

Seeking protection under a tree may be inviting danger since the generally damp trees are good conductors of electricity, with no Faraday cage like safety offered.  Sometimes the trees themselves may catch fire because of intense heating of its parts.

Venus, Earth Satellites and UFOs

Human fascination for UFOs (Unidentified Flying Objects) is so strong that anything moving in the sky often ignites interest and promptly gets dubbed as a UFO if the viewer has no idea of what it is.  At times planet Venus is seen as a spectacularly bright evening object low on the evening horizon and people unaware of its identity frequently mistake it for a UFO, often speak of it as such and some media even report it as such.  The sight can be eerie (and even scary for believers in UFOs) if a crescent Moon is also visible nearby as is the case sometimes (see picture below).  The most preferred interpretation is that it is an alien ship on a visit to planet earth.  Some decades ago one such newspaper report caused so much stir that it forced the attention of the Indian meteorological service who promptly promised a thorough investigation! I do not know if the investigators discovered the simple truth and publicized it.

Nowadays one can often see in the post sunset sky a number of bright man-made earth satellites in rapid motion and act as UFO ‘candidates’ among the uninitiated.  The huge International Space Station (ISS) and the rather frequent ‘Iridium flares’ (these are communication satellites, about 80 of them in low earth orbit, flaring up momentarily as a very bright flash of light when its reflective solar panel comes in the line of sight of the observer) are nowadays seen so frequently that they have even lost some of their sheen as possible alien UFOs.  Incidentally, one can obtain advance information about the visibility and path/location of such man-made earth satellites at any place on earth from popular websites such as

Mobile myths

Nowadays it is rare to find anybody without a mobile phone handset that gives the power of instant communication with anyone anywhere.  With such widespread use, it is no wonder that the mobile handset is at the heart (no pun intended) of numerous myths and misconceptions associated with the fact that they receive or transmit electromagnetic radiation at very low frequencies.  Let me refer to just two of them here – that their use can cause cancer or affect the heart, the latter when kept in shirt pockets for too long.  There is no evidence for either though such evidence has been available only for the short duration of time the devices have been in use since their invention.  While any such prognosis has to wait years and even decades of regular future use, any possibility of harmful consequences will have to be weighed in the light of the following facts.

The human body is being bombarded all the time by a variety of electromagnetic radiations, ranging from the very energetic and harmful ultraviolet rays to low-energy harmless radio waves that we use for all types of communication all the time.   Though an ozone layer high above the earth’s atmosphere provides a blanket of safety against the ionizing ultraviolet radiation, there is always some residual high energy radiation (and cosmic ray particles) from which the body is never immune.  Compared to the total energy the human body absorbs relentlessly from such sources the additional contribution from mobile transmitters and receivers is negligibly small and cannot possibly pose any significant additional long-range threat to the human body.

Navagrahas (Nine Planets)

Despite all that we know about our (heliocentric) planetary system in modern Astronomy, the extraordinary and widespread myth persists about the existence of navagrahas (nine planets) that are supposed to influence human affairs in mysterious ways depending on their relative positions, especially at the time of birth of the person concerned. These nine planets are not the ones we are familiar with in Astronomy – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto, the last of which was incidentally demoted some years ago from the list of planets for perfectly sensible scientific reasons.  These Navagrahas know from ancient Indian Vedic times are: Surya (Sun), Chandra (Moon), Mangala (Mars), Budha (Mercury), Brihaspati (Jupiter), Shukra (Venus), Shani (Saturn), Rahu and Ketu.  While the first two are indeed objects of the solar system, though not planets, the last two are not even material objects of any kind; they are just imaginary points in space - the points of intersection of the paths of the Sun and the Moon as they move around the celestial sphere (see figure below).

Compounding the myth of the navagrahas is the utterly irrational and widely practiced belief that a certain period of time each day, related in some ways to the concept of Rahu, is inauspicious for performance of any important human activity.  This is one of the most astoundingly superstitious and blind beliefs prevalent in the Indian society, and large numbers of people from all walks of life refuse to do anything that they consider important during this period called rahukaalam.  I once had the mortification of having to wait a considerable time for the staff and students of a reputed academic institution to turn up for the day’s work because their institution’s head didn’t want my visit to begin during such a rahukaalam! On another similar occasion when I was being hurried to begin my work before the dreaded rahukaalam set in, I deliberately stalled the proceedings and started work only after the period began, much to the chagrin of the man in charge!  It didn’t make any difference to the eventual outcome of my assignment.


Some years ago I was a resource person at a short term course for teachers and used to engage the pre-lunch session each day, followed by joining the participants for lunch arranged at the venue.  A long duration partial eclipse of the Sun took place on one of those days and, at the organizers’ request, I had made a multimedia presentation relating to the event and showed the eclipse itself live with a small telescope I had taken along.  Curiously, I observed that some of the participants were not interested in watching the eclipse show though they had all attended my classroom presentation.  It was only at the usual lunch time I realized why.  No lunch was being served that day because, as the organizers explained to me, most of the participants had indicated that they would not be eating lunch that day!  They were dutifully obeying centuries of superstitious tradition that forbade them from eating anything during an eclipse.  I had no doubt they would all take a bath after the eclipse ended and eat anything only thereafter.

Well, even after this experience, my belief in the long-term transformative potential of education is neither a myth nor a misconception.


Govinda Rao V Adamane said...

Very interesting

Poulose Master said...

Thank you Sir. It is really educative and interesting. Even now, 40 years after leaving RCE, I learn lots from you. Pranams again......

Jayant Murthy said...

These have real consequences. For instance, politicians are protecting us from the non-existent mobile menace by adding extra safeguards which ultimately will cost us money.

On another note, I, unfortunately, also skipped lunch on the last eclipse day. I was on TV and they wouldn't let me go until after lunch.

Anonymous said...

Thank you Dr Prasad. I do not know who sent your link to my email but i am thankful to them as I get to read such insightful pieces amidst all the trivia that bombard us today. I am a science person myself but some of these things like the Moon illusion had escaped me too. However, regarding the mobile tower dangers, we read many studies these days about why they are bad. Are these studies bogus?

Anonymous said...

Thank you sir,
I knew that the china wall, the Birahatheswarar temple kalasam, and the cell phone myths.

but when i explain this people are arguing without any basic concepts.

I was searching such a person like you. Thank you very much for your explanations.

Here some myths Snake drink milk, Morning star (is not venus which is a planet), snakes can hear sounds are need to explain. Pls explain in this blogs.
Thanking you.
Best regards
Devamanohar Michael

Shan Ramiah said...

Dear Dr Prasad,

I stumbled on your blog on Myths during a browsing session. I must say, it was very educative. I feel such articles should be shared by all readers with their contacts, so that young and impressionable minds are devoid of such myths.
There is a popular belief among many people in Kerala and Tamilnadu that the 'Kalasams' of old temples turn in to Iridium due to the effect of lightning and such other environmental events, over decades / centuries. There is a big racket going on, making people believe in such 'scientific happenings'. It is not only those without education, but even those with some knowledge of science ( perhaps we should call them pseudo educated or mal-educated)tend to believe in such stories and are drawn in to such rackets. An article by you with scientific reasoning will go a long way in exploding such myths.

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