Ring of Fire! – The Great Annular Solar Eclipse of 15 Jan 10

After I started the blogging phase of my career last February, my initial posts focused so much on total solar eclipses and my incidental China travelogues that I had little time to write about yet another solar eclipse of great interest that I had witnessed exactly one year ago today.  To be better late than never, I am writing about it now to mark its first anniversary.  The event was the great annular solar eclipse that could be seen from most parts of south India on the afternoon of 15 January 2010.

How are eclipses caused?

Before I proceed further, let me explain in lay terms how eclipses are caused, something I should have done in one of my earlier posts.  At predictable times during the motion of the Moon around the Earth and of the two together around the Sun, the three objects can be found in a straight line for short durations of time.  When the Earth lies between the Sun and the Moon (on a full moon day), the latter can be found in the shadow of the Earth and hence sunlight will not be falling on it directly.  This is when a lunar eclipse occurs.  As seen from any point on the Earth, the eclipse may be partial or total.  One might expect the Moon to be completely hidden from view during a total lunar eclipse.  However, the whole of the Moon can be seen clearly as a faint coppery red object because of sunlight scattered by the Earth’s atmosphere falling on the lunar surface and thereby illuminating it.  It is a wonderfully beautiful sight to behold!  Would it be fair to regard the Moon as truly eclipsed?

When the Moon lies between the Sun and the Earth (on a new moon day), the latter can be found in the shadow of the Moon and hence sunlight may not be falling on certain parts of its surface at any given time.  This is when a solar eclipse can occur.  As seen from any point on the Earth, the Sun may be eclipsed, partially or wholly, depending on the geometry of the three bodies.  At any instant during a total solar eclipse, the Sun will be completely obscured and day turns very nearly into night for the duration of totality.  I say ‘very nearly’ and not ‘totally’ since scattering by dense clouds in the earth’s atmosphere can throw a bit of sunlight into the region of otherwise total darkness, something I noticed prominently during my sighting of the total solar eclipse of 22 July 2009 in China (see my blog post dated 23 Feb 2010).  The visibility of the solar corona during the total phase is one of the most spectacular shows put up by nature as vividly described in my earlier posts.  The rarity of total solar eclipses at any particular location on earth makes the experience all the more memorable.

Solar and lunar eclipses as seen from the Earth would not have been possible at all but for a very fortuitous and remarkable circumstance relating to the three celestial bodies.  The apparent sizes of the Sun and the Moon as seen by us on Earth just happen to be very nearly the same, approximately half a degree in angular diameter.  The sizes however are not constant because of small but distinct periodic variations in the distances between any two of the three bodies.  This makes the apparent diameter of the Moon sometimes slightly larger than that of the Sun; this is when the solar eclipse can be total.  When the reverse happens, we can have the outer parts of the Sun visible as a thin annular ring even when the three bodies are aligned perfectly; this is when an annular eclipse occurs.  This is what happened on the afternoon of 15 Jan 2010, but there was something very special about this event.  The duration of the totality phase at its peak was more than eleven minutes and this will be the longest in this millennium!*  The angular diameter of the Moon in relation to that of the Sun was very close to the smallest possible. For this reason the size of the Sun’s ‘ring of fire’ was so large that the reduction in the overall brightness of the normal Sun could barely be noticed.  I shall return to this point later to discuss an extraordinary post-eclipse news item appearing on the front page of a major English daily newspaper.

[*At its peak, the eclipse’s annular phase lasted for about 11 minutes and eight seconds, which was the longest since the annular solar eclipse on 4 January 1992, which lasted for about 11 minutes and 41 seconds. This duration will not be equaled or exceeded until the annular solar eclipse of 23 December 3043.]

The following diagram (grotesquely exaggerated and out of scale) illustrates the geometry associated with the formation of total, annular and partial solar eclipses:

The Location

The great annular solar eclipse of 15 Jan 2010 could be seen over a large area of the Indian subcontinent.  The totality phase itself was visible from most places in southern Tamilnadu.  The central line of the belt of totality passed through Dhanushkodi adjoining Rameshwaram off the eastern coast of the state (see the NASA-Espenak map below, zeroed in for this region).  For this reason, Dhanushkodi offered itself as the ideal location for seeing the eclipse.  Not only could the total phase be seen for the longest duration (over ten minutes) but also one could expect to see a near-perfect annular ‘ring of fire’ at the half way point of totality.  Naturally, that is where I was headed.  An added motivation was that I would be seeing the famous temple town of Rameshwaram for the first time after two ‘failed’ attempts earlier because of terrible weather conditions.  I would also be seeing the world famous 2.3 km long Pamban Bridge linking the island to the mainland since 1914.  The location presented a great photo opportunity for me.

 

[All pictures/illustrations in my posts can be blown up to their full size by clicking on an item and opening it in a separate window]

The Preparation

The eclipse day was a Friday and this was preceded by the strongly traditional Pongal /Sankranti festival (holi)day on 14 January.   It meant a long holiday weekend for most people and I expected a huge influx of tourists into a place like Rameshwaram.  I therefore started my preparations well in advance.  The first thing I did was to book hotel accommodation for the 14th.  I was glad to be able to do it online from the comfort of my home.  But the hotel itself turned out to be far from comfortable despite a hefty price tag.

I had planned to travel to Madurai from Mysore by train and take the road route to Rameshwaram thereafter.  I made an online railway reservation far in advance of the date of journey; yet found myself in the much dreaded waitlist.  Normally, the transition from the waitlist to the confirmed list is smooth, but this time I had no such luck.  I stayed put in the waitlist even three days before journey day and realized I had to do something about it.  When I discovered that the regular overnight bus services from Mysore to Madurai were fully booked, I sought the intervention of a friend who in turn had a friend in the railway offices.  Luckily this worked and I got the premium priced tatkal reservation just in time.

The Journey

I reached the famous temple city of Madurai on 14th morning by an uneventful and comfortable overnight train journey, but what followed was anything but comfortable.  I boarded an overcrowded private bus bound for Rameshwaram and a considerate passenger squeezed me into a part of his own seat, something not uncommon in India in both buses and trains.  I had to travel this way for the best part of the four hour journey.  The bus fare was ridiculously low, but I had to pay a heavy price in terms of having to put up with the horrendous cacophony emanating from an ‘in-house’ movie being played on a TV set.  One can rarely expect to travel in private buses, especially in Tamilnadu, without being subjected to such assault on the eardrums inflicted by gratuitous bus operators by way of ‘free entertainment’.  The bus conductor refuses to switch off or even reduce the sound volume on the plea that the passengers ‘demand’ such entertainment and he cannot afford to displease them.  I am not sure if most passengers indeed really demand such punishment, but they certainly don’t seem to object!  While it is easy to escape the video component of the entertainment, there is no way this can be done with the audio blasts from everywhere within the vehicle at full throttle.  I had taken with me a pair of ear plugs for such a contingency, but it was like fighting a huge fire with a water sprinkler.   It was with uncontrolled relief that I got out of this torture chamber at the bus stand in Rameshwaram, took a short auto ride and checked into the hotel located close to the famous temple complex in the town.

As it turned out, there was indeed a heavy influx of people into Rameshwaram, but most people had come only to visit the temple because of the special significance of the day and not to see the eclipse.  Only a tiny fraction of them had come primarily to see the eclipse and they were all to be seen at Dhanushkodi the next day afternoon.  It was not a small number but it was definitely not a crowd.

I spent the rest of the day exploring the temple complex and taking pictures both inside and outside.  Here are two representative pictures of the temple:

The Rameshwaram temple is often compared to the legendary Madurai Meenakshi Temple, but I rate the latter much higher in almost all respects.  The interior presents some spectacular views, like the one in the second picture, but it suffers from some poor maintenance, both inside and outside.  The floor appears to be always wet, grimy and difficult to walk on. 

 

Early next morning, on the day of the much anticipated eclipse, I found time to explore the famous Pamban Bridge and its surroundings.  Here is a picture of the historic railway bridge taken from the Rameshwaram end of the road bridge which is partially visible on the left.

Before moving on to Dhanushkodi I had some more time to spend both outside and inside the temple complex.  This was just before the visitors were shunted out and the doors were shut apparently to ward off any possible evil effects of the impending eclipse! This scene must have been reenacted that morning in most places in the country.

On to Dhanushkodi

Most of Dhanushkodi is a long and very narrow strip of sandy land surrounded by the sea and uninhabitable.  The vantage point I had considered for observing the eclipse was about 20 km away from my hotel and I could have easily reached it by a local bus.  However, no buses were plying that morning apparently because of the state governor’s visit to the town and the consequent disruption of road traffic!   After a long and futile wait, I tried to hire an auto. There were very few of them and the driver of one of them who was willing to take me on demanded such a huge amount that I thought under normal circumstances I could have hired a helicopter for such a sum.   It reminded me of a similar experience in China when I was trying to reach the hilly place from where I had planned to see the total solar eclipse on 22 July 2009.  I noticed a couple from Mumbai who apparently also wanted to go to the same place and for the same purpose.  We met, exchanged introductions and decided to join hands in the common endeavour.  We bargained hard, settled for an affordable and shared return journey and were soon on our way.  My companions were a recently retired seismologist from BARC, Dr Kovlankar, and his wife.  We got to know each other very well during the rather long journey on a difficult and narrow road with heavy one way traffic of mostly private vehicles. We got down at a convenient location well before the commencement of the totality phase of the eclipse, the initial phase having already started much earlier. 

The Ring of Fire!

My companions and I found ourselves among a fairly large number of small scattered groups of people most of them having come there for the same purpose.  Some of them had professional quality cameras and viewing devices, including small telescopes, equipped with solar filters.  I had taken the same improvised binocular device that I had used to observe the total solar eclipse in China on 22 July 2009 (See my blog post dated 23 February 2010 and one of the accompanying photographs), but had not planned on any photography.  I had avoided the temptation to carry my Meade 5” Maksutov-Cassegrain telescope with a Canon SLR camera attachment.  This was mainly because I was travelling alone and the attendant logistic problems.  While I have passionately practiced both Photography and Observational Astronomy as major hobbies, I have not tried to combine the two and done anything worthwhile by way of Astrophotography.  This is one of my major shortcomings, but living most of the time in heavily light polluted urban areas is perhaps mainly to blame for it. 

Dr Kovlankar had an excellent digital SLR camera setup along with a very good sheet of solar filter.  He was not sure if he could use the filter with the camera effectively.  We put our heads together and came up with a simple improvisation which worked wonderfully well.  Here is a picture of the camera with the improvised filter with which he took a series of decent pictures of the eclipse at regular intervals and produced a video clip later (See: http://picasaweb.google.com/Vinayakkol60/ECLIPSE15JAN2010?feat=directlink). 

Here is a subset of the sequence of pictures he took that day:

Even as the totality phase was approaching, the Sun was beating down harshly from a cloudless and beautifully clear sky. The three of us were lucky enough to be able to rest frequently under a nearby abandoned thatched roof apparently erected by some fishermen.  Most other viewers had to brave it out under a merciless sky.  Many visitors had come there only to see the place and the eclipse was an unexpected bonus for them.  Those who had any type of viewing device shared it readily with those who did not.  Some of them were even trying to look at the Sun through a slit formed between their extended fingers.  They must have discovered that the Sun was far too bright to be viewed this way and spared themselves the potential danger to their eyesight.

  

Soon it was time for the real show.  Just minutes before the annular phase started, we began to feel a slight drop in temperature giving us some respite from the heat, and an eerie silence set in among the viewers.  As the annularity set in, we could observe a marginal drop in the brightness of everything around us, but this was barely noticeable, especially since the viewer interest was focused on the eclipse itself.  As expected, the event lasted a little over ten minutes and at the mid-point in time (around 1:22 PM IST) we could all see a near perfect annular ring of the still very bright Sun.  The visibility was perfect all through and there was not a whiff of cloud anywhere in the sky.  As could only be expected, the much touted ‘ring of fire’ appeared like anything but a fire through any of the viewing devices. Yet it was a spectacular sight - in my view next only to that of a total solar eclipse.  Of course, the whole sequence of events could be seen only through safe filters, unlike a total solar eclipse which can be seen with bare eyes (in fact, should be seen with bare eyes) during the totality phase – and only during the totality phase.  The temperatures on the surface of the Sun are close to six thousand degrees, but a fiery appearance of the annular ring can only be seen through appropriate special filters, not through a neutral density solar filter most people were using.

The Return

As generally happens, the end of a major event comes as an anticlimax.  This eclipse was no different.  People started to pack up and leave as soon as possible to avoid a possible traffic jam.  We had no such concern since our vehicle was a highly maneuverable three wheeler.  I dropped my companions off at their hotel, went back to mine, packed up and was anxious to get back to Madurai as early as possible.

At the Rameshwaram bus stand I boarded a bus that was ready to leave for Madurai and this time had no difficulty getting into a comfortable seat.  But I had to endure the audio assault all over again and at the same decibel level for another torturous four hours before I reached Madurai.  I decided to never again place myself in a situation where I would have to travel in a private bus in Tamilnadu. Till now I have been successful.  However, I find that the disease has spread to Karnataka also and unbelievably, the latest victim is the Chamundi express train between Mysore and Bangalore.  I am thankful that other trains have been unaffected so far.

    

At Madurai bus station I had no difficulty getting into a KSRTC bus bound for Mysore on an overnight journey.  I boarded it only after ensuring that no TV set had been installed inside.  The next morning I was back home to reflect on another memorable experience.

Pall of Darkness … and Ignorance

When I browse my morning newspaper, a reputed national English daily, I generally do so from the last page backwards to the first page.  That morning I was curious to know if it carried anything on the great eclipse.  Sure enough it did, right there on the front page.  What I read was shockingly unbelievable.  Quoting its reporter from Dhanushkodi describing the experience of the previous afternoon, it went on to say, “….. A pall of darkness enveloped this region and a golden ring of fire appeared in the sky....”. It took some time for me to realize that this astonishing piece of (mis)information was indeed printed on the front page of such a widely circulated frontline publication.  I thought I should immediately convey my dismay to its editor and sent the following message by email:

Sir, I am bemused to read the description, “A pall of darkness enveloped this region and a golden ring of fire appeared in the sky....", appearing on the  front page of today's edition of your esteemed newspaper that is normally  well-known for its accurate and balanced reporting.  If your reporter saw anything like what he has described, he could not have seen the event from Dhanushkodi or, for that matter, from anywhere else along the path of annularity of the eclipse. I was in Dhanushkodi to observe this historic eclipse and saw, as expected, only a modest drop in the intensity of sunlight as the annularity phase approached and receded.  There was no darkness of any kind whatsoever.  Darkness appears only during total solar eclipses.  A spectacular ring was indeed seen through optical aids such as cameras,  binoculars and telescopes equipped with a solar filter, but this could hardly be described as a 'ring of fire' unless the view was through professional quality telescopes equipped with special types of filters.  Most people watching at Dhanushkodi had no such special equipment.  Your reporter appears to have fallen prey to the kind of sensationalism that afflicts many other newspapers and media in the country.

Not unexpectedly, the newspaper did not care to print my letter or issue any statement.  It might have been too embarrassing for the editor to accept that his reporter had committed a monumental blunder.  The only way the reporter could have seen a 'pall of darkness' enveloping Dhanushkodi that afternoon was by keeping his eyes shut at the time of the annular phase.  I wish he had also kept his communication channel shut at the same time!

I had copied my email to many of my friends and professional colleagues.  Most of them, including one from the Indian Institute of Astrophysics in Bangalore, wrote back to me in whole hearted support of my letter to the editor.   These were just lone voices drowned in a sea of ignorance and stupidity. 

A few days later, while scanning through a local language newspaper, I found a short column of factually accurate report on the scientific and technical aspects of the annular eclipse of 15 January.  However, on the same page, I found three long columns describing the evil portents of the eclipse in meticulous detail by a noted ‘astrologer’.  He had discussed at length how the event could influence almost every aspect of one’s daily life and gave detailed recipes on how to guard against each of them!  Of course they included avoidance of viewing the eclipse in any manner!  It is amazing how any established body of knowledge could support such outrageous claims and, adding insult to injury, also claim corrective possibilities through mere performance of some elaborately concocted and bizarre rituals.  Isn’t this just voodooism in a different, perhaps more refined, garb?  Anybody who tunes into any local language TV channel early in the morning cannot but be bombarded by all kinds of unscientific and irrational precepts and exhortations that seem to be designed just to insult human intelligence.   So much for the educational value of modern media. 

Tailpiece

Any of my posts on eclipses is incomplete without some form of reference to my great friend, Dr Narasimhan of Virajpet, Coorg.   This one is no exception.  Sometime after my return from the eclipse visit he drew my attention to his latest blog post in which he had written in considerable detail about his own experiences in Rameshwaram and Dhanushkodi.  Unknown to each other, we were at the same place at the same time doing the same thing!  We both felt very bad about not knowing each other’s plans and attempting a joint trip or at least meeting at Dhanushkodi which would have been so easy to do.  He sent me one of the photographs of the eclipse he had taken with a Nikon P90 camera that day.  It shows a near perfect annular ‘ring of fire’ with a date and time stamp (slightly in error) imprinted.  I am reproducing it here with my compliments:

Epilogue

Eclipse chasers like me will have to wait a long time for the next total solar eclipse from any location on earth.  It is due to take place partly over north eastern Australia on the morning of 13 November 2012.  The best place to view it appears to be the city of Cairns in Queensland (see NASA-Espenak map below).  I certainly don’t want to miss it.  An added attraction for me would be the Great Barrier Reef, one of nature’s greatest wonders, which can also be visited easily from Cairns.

Delhi - Legacy of Lutyens and the Mughals – Personal Photo Album Part 5

The historic cities of Agra, Jaipur and Delhi form a ‘Golden Triangle’ of major Indian tourist attractions.  My earlier travelogues covered the first two and it is appropriate that I complete the triangle with a photo album of the third, the nation’s capital and one of the world’s largest and most ancient metropolises.

  

Since my first visit in 1963, I have visited Delhi innumerable times and seen most of its major attractions.  Practically all these visits were on official work, related to my employment with the National Council of Educational Research and Training (NCERT), whose headquarters is located in a sprawling campus adjacent to the Indian Institute of Technology (IIT) in posh south Delhi.  I have seen the transformation of a metropolis into a megapolis during this period.  Even after retirement from my service in the year 2000, I have visited the nation’s capital many times and all the photographs presented in this album were taken after 2005 with several digital cameras.  These photographs naturally represent only a very small and rather ill organized cross section of my collection. 

[All pictures in my posts can be blown up to their full size by clicking on a picture and opening it in a separate window]

Raisina Hill

Where else to begin my photo album than at the magnificent Rashtrapathi Bhavan and the nearby central government secretariat, perhaps the most visible handiwork of the legendary British architect Edwin Lutyens, located on Raisina Hill?  Here are two photographs symbolic of Lutyens’ Delhi.  Only a part of the north block of the secretariat is seen in the second photograph.

India Gate

The India Gate at the other end of the famous Rajpath starting from the Rashtrapathi Bhavan is as symbolic of Delhi as is the Gateway of India in Mumbai, the financial capital of the nation.  Here are two pictures showing the famous monument and its surroundings, the focus of special attention at the Republic day parade on January 26 every year:

Jantar Mantar

The Jantar Mantar in Delhi, located close to the busy and buzzing Connaught Circus, is a smaller version of the one in Jaipur built by the famous astronomer-king Maharaja Jaisingh II in early eighteenth century.  The complex itself is relatively quiet, well maintained and has an impressive collection of brick buildings and a variety of yantras (measuring instruments).  Here is a view of the complex showing some of the red brick structures:

Teen Murti

The Teen Murti Bhavan is a great building dedicated to the memory of India’s first prime minister, Jawaharlal Nehru.  It houses a museum and a planetarium within a large and serene complex.  The entrance to the complex shown in the following picture has an impressive monument built as a war memorial.

The Lotus Temple

After the Taj Mahal in Agra, I rate the Baha’i House of Worship, appropriately called the Lotus Temple, as the greatest architectural marvel in the country.  Being the most visited sight in the capital, it appears to have attracted even more visitors than the Taj Mahal.  Shaped like a lotus flower, with beautifully symmetrical petals made of pure white marble, it is a breathtakingly beautiful sight from any vantage point, particularly from any aircraft flying overhead as I discovered several times.  It is located in a vast tract of greenery which in itself is a nature lover’s delight.  Here are three views of the structure in two of which I have tried to capture the surroundings as much as the structure itself.

 

Humayun’s Tomb

President Barak Obama of the USA is one of the very few high level foreign heads of state to have visited India without also having visited the Taj Mahal at Agra.  He sought to make up for the lapse by visiting what has been touted as Delhi’s equivalent of the famed monument, Humayun’s tomb.  Though the comparison is rather overstretched, Delhi’s monument is very impressive in its own right and one of several UNESCO designated world heritage sites in the city.  Unlike the Taj which is built from pure white marble, it is constructed mostly from red bricks.   It seems inappropriate that it was built in memory of someone like Humayun rather than his more illustrious predecessor Babar or successor Akbar.  Here are three pictures of it from my collection:

The Qutab Minar

The Qutab Minar in south Delhi is the world’s tallest brick minaret, standing 72.5 metres tall.  It is one of the earliest and most notable examples of Indo-Islamic architecture. The minaret is part of a complex, housing several ancient and medieval structures and ruins.  Here are two pictures showing the Qutab Minar:

The Red Fort

Located in old Delhi close to Chandni Chowk, one of the busiest places in the country, the Red Fort (Lal Qila) is another great landmark in the city.  As a very popular tourist attraction it springs into special prominence once every year when the Indian Prime Minister hoists the national flag and makes a speech from the ramparts of the fort to mark the nation’s Independence Day on August 15.  Here is the famous red brick facade of the fort:

Inside the Red Fort complex there are a number of buildings and structures, the most attractive of which is probably Diwan-i-Aam, much like its counterpart in the Agra fort.  Here is a picture showing the ornate inlay work and intricate carvings on its walls:

Birla Mandir

The Laxminarayan Temple, popularly known as the Birla Mandir, is a wonderful example of Indian temple architecture seen in many parts of northern India.  Here is a frontal view of it:

Raj Ghat

Located on the banks of river Yamuna, Raj Ghat marks the spot of Mahatma Gandhi’s cremation in 1948 on a black marble platform which is left uncovered.  It is a great place, befitting the memory of the father of the nation and superbly maintained.  Here are two pictures I took with the memorial seen behind each of two different trees which I found fabulously attractive and particularly appropriate to the situation.

Down Memory Lane

I round off my last blog post of this year with a picture that touches a personal chord.  Whenever I visited Delhi on official work I used to stay in one of the guest houses inside the NCERT campus in which the most attractive building is the Central Institute of Educational Technology (CIET), one of the institutions forming part of the NCERT.  It is a superb red brick building, apparently inspired by many of the red brick structures, old and new, dotting the city.  The best part of it however is the greenery surrounding it and the serene atmosphere it creates, something that I have always valued. 

Search for Extra Terrestrial Intelligence [SETI]

Preamble

When astronaut Neil Armstrong took that small step on the Moon on 20 July 1969, it was indeed a giant leap for all mankind.  After the Apollo 11 lunar explorers’ return to earth, the then American President Richard Nixon went so far as to say, “This is the greatest week in the history of the world since Creation”.   This must have sounded like music to the ears of the creationists and their descendants, the intelligent design theorists, in the western world who visualize human life on earth as just a week’s handiwork performed by a super intelligent being.  Nature of course has been far less enterprising and taken millions of years to do the job through a long drawn out and complex evolutionary process.  Nixon may or may not have used the term ‘creation’ in its biblical sense, but he was not far off the mark if he implied that the event was the greatest since human life itself took firm root on planet earth, whenever this may have been.  To celebrate the next such momentous event in history we may have to wait until one of the most tantalizing questions of all time facing human civilization is answered definitively – is there intelligent life elsewhere in the universe?  If and when this is answered in the affirmative, an even more momentous event would be the establishment of contact with such intelligent life.  It could indeed be a tremendously long wait and very far into the future.

Since time immemorial, mankind has been fascinated by the possibility of intelligent life outside our planet earth.   While there has been no credible factual evidence of any kind whatever even up to the present day, writers of science fiction, movie makers and the modern media have given themselves unfettered liberties and let their imaginations run riot.   If their claims are to be believed, the earth is crawling with a plethora of uninvited extraterrestrial aliens deposited by UFOs (Unidentified Flying Objects) flying all around us, whose favorite pastime seems to be abducting or at least frightening hapless innocent earthlings!  Ufology has become nearly as popular as, but no more scientific than, Astrology.

With the discovery of innumerable stars having physical properties and chemical composition similar to that of our Sun in the last two centuries, wild imagination has given way to meaningful speculation about extraterrestrial life, including intelligent life as prevalent on earth.  It makes eminent scientific sense to expect at least a tiny fraction of these stars to have an earth-like planet with similar life forms, including intelligent life.

In the latter half of the twentieth century, scientists decided that the best way to approach the problem would be to scan the skies and ‘listen’ for non-random patterns of electromagnetic emissions such as radio or TV waves in order to detect another possible civilization somewhere else in the universe.  This is the essence of the ongoing worldwide SETI (Search for Extraterrestrial Intelligence) effort.

Radio SETI

Radio is believed by most scientists to be the best means we have for interstellar communication, considering the vast distances involved. Radio waves, like all electromagnetic radiation, travel at the speed of light – 300,000 kilometers per second. This is the fastest velocity possible, and yet even Proxima Centauri, the closest star to our own Sun, is so far away that light takes approximately four years to make the journey. In contrast to the speed of light, a typical fast spacecraft we have with current technology travels about 15 kilometers per second. At such speeds, it would take a spaceship about 80,000 years to reach our nearest neighbor!  In other words, interstellar travel by earthlings is virtually impossible for the foreseeable future even within our own galaxy.  We have to look for other, indirect, means to look for evidence of intelligent life elsewhere in our galaxy.

Radio waves are thought to be the optimum band of the electromagnetic spectrum for interstellar communication because they are relatively free of the absorption and noise associated with other areas of the spectrum.  Radio, visible light, and the near infrared are the only electromagnetic radiations able to penetrate the earth's atmosphere, and of the three, radio is not as easily absorbed by interstellar gas and dust. In addition, stars are generally ‘quiet’ in the radio frequencies. This makes radio a natural candidate for a ‘beacon’ by an advanced civilization, or for interstellar communication between such civilizations.

In late 1959 and early 1960, the modern Radio-SETI era began when Frank Drake conducted the first such SETI search at approximately the same time that Philip Morrison and Giuseppe Cocconi published a key journal article suggesting this approach.

Project OZMA

Project OZMA was the first systematic attempt to detect artificial radio signals from nearby stars. Named after the princess in Frank Baum's Wizard of Oz, it was the brainchild of American radio astronomer Frank Drake working at the Green Bank observatory in West Virginia, USA.  Drake began preparations for Ozma in 1959, the same year in which the seminal theoretical paper on SETI by Philip Morrison and Guiseppe Cocconi was published in the British journal Nature. These developments, although occurring more or less simultaneously, were quite independent of each other.  However, both concluded that the best chance of success would come from searching at a radio frequency of 1,420 MHz (corresponding to a wavelength of 21.1 cm) since the 21-centimeter line of neutral hydrogen in the Galaxy might represent a natural wavelength at which intelligent species would try to communicate. Although, after 150 hours of ‘listening’ from two nearby stars the effort proved futile, it was to be the forerunner for many more, increasingly sophisticated, searches which continue to this day at ever increasing pace.

SERENDIP

Project SERENDIP (Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations) was the first major organized large scale effort, begun in 1979.  It underwent further stages of improvement.  SERENDIP IV consisted of 40 spectrum analyzers working in parallel to look at 168 million narrow (0.6Hz) radio frequency channels every 1.7 seconds.  It was effectively a 200 billion-instructions-per-second supercomputer. The equipment was installed piggyback, without affecting the primary work of the facility in any way, at the 1000-foot non-moving Arecibo National Radio Telescope Observatory – the largest radio telescope in the world – in Puerto Rico, USA, and managed by the University of California at Berkeley.  SERENDIP V, the most recent version of the project, began in 2009.  It employs a two billion channel digital spectrometer covering 300 MHz of bandwidth.

SETI@Home

Most of the SETI programmes in existence today require fast computers that can analyze data received from the telescope in real time. None of these computers look very deeply at the data for weak signals nor do they look for a large class of signal types.  This is due to the limitation on the amount of computer power available for data analysis. To probe into the weakest signals, a greatly enhanced amount of computer power is necessary. It would take a monstrous supercomputer to get the job done. SETI programmes cannot afford to build or buy that computing power. There is a trade-off that they can make. Rather than a huge computer to do the job, they could use a smaller computer but take longer to do it.  But then there would be lots of data piling up. What if they used a huge number of small computers, all working simultaneously on different parts of the database? Where can the SETI team possibly find thousands of computers they would need to analyze the data continuously streaming from the Arecibo Radio Telescope?

There are already hundreds of thousands of computers that are available for use, owned by individuals and institutions all over the world. Most of these computers sit around most of the time accomplishing absolutely nothing and wasting electricity as well. This is where SETI@home comes into the picture. The SETI@home project harnesses the potential of such computers to get its job done.  It has built up a huge network of computers whose services are being volunteered by millions of users all over the world.  The user software can be run either exclusively during the idle time of a computer or continuously as an additional task while being used for other purposes as well (multi-tasking).  Most serious volunteers prefer the latter.

The SETI data analysis task can be easily broken up into little pieces that can all be worked on separately and in parallel. None of the pieces depends on the other pieces. Of course, there is only a finite amount of sky that can be seen from Arecibo through the fixed telescope. In the last two decades the entire sky as seen from the telescope has been scanned several times.

Breaking up the Data

Data are recorded on high-density tapes at the Arecibo telescope in Puerto Rico and sent to Berkeley. They are then divided into 0.25 MByte chunks (which are called ‘work-units’). These are sent from the SETI@Home server over the Internet to volunteers around the world to analyze. There are nearly 3 million such actively participating volunteers worldwide.

SETI@home looks at a width of 2.5 MHz of data, centered at 1,420 MHz. This is still too broad a spectrum to send to any one volunteer for analysis, so this spectrum space is broken up into 256 pieces, each 10 kHz wide. These 10 kHz pieces are now more manageable in size.  The SETI computer sends out about 107 seconds of this 10 kHz data in the form of a ‘work-unit.’

Sending the Data

SETI@home connects to the volunteer’s computer via the Internet when transferring data. This occurs only when the computer has finished analyzing a work-unit and wants to send back the results (and get another work-unit). The data transmission lasts just a few seconds with most common modems and disconnects immediately after all data is transferred.

The SETI staff keeps track of the work-units in the Berkeley campus of the University of California with a huge database. When the work-units are returned to them, they are merged back into the database and marked ‘done.’ Their computers look for a new work-unit for the volunteers to process and send it out, marking it ‘in progress’ in the database. 

What SETI@home looks for

The easiest way to answer this question is to ask what we expect extraterrestrials to send. We expect that they would want to send us a signal in the most efficient manner for them that would allow us to easily detect the message. Now, it turns out that sending a message on many frequencies is not efficient. It takes lots of power. If one concentrates the power of the message into a very narrow frequency range (narrow bandwidth) the signal is easier to weed out from the background noise. This is especially important since we assume that they are so far away that their signal will be extremely weak by the time it gets to us.  So, we're not looking for a broadband signal (spread over many frequencies); instead, we are looking for a very specific frequency message. The SETI@home screen saver program that displays the work in progress on the volunteer’s computer monitor acts like tuning a radio set to various channels, and looking at the signal strength meter. If the strength meter goes up, that gets our attention.

Another factor that helps reject local (earth-based and satellite-based) signals is that local sources are more or less constant. They maintain their intensity over time. On the other hand, the Arecibo telescope is fixed in position. So the sky "drifts" past the focus of the telescope. It typically takes about 12 seconds for a target to cross the focus (or ‘target beam’) of the dish. We therefore expect an extraterrestrial signal to get louder and then weaker over a 12 second period. We are looking for this 12 second ‘Gaussian’ signal within the 107 seconds of data. We can also expect the signals to be pulsed since this would be a very efficient means of coding information.

Because of the rotational motion of the planets, both ours and ‘theirs’, there is likely to be a ‘doppler shifting’ or changing frequency, of the signal because of our relative motions. This might cause the signal to rise or fall in frequency slightly over the 12 seconds. These are called ‘chirped’ signals.  In summary, we look for ‘chirped’ and ‘pulsed’ signals as indicated in the adjacent graph.

Signals that show a strong power at some particular combination of frequency, bandwidth and chirp are subjected to a test for terrestrial interference. Only if the power rises and then falls over a 12 second period (the time it takes the telescope to pass a spot in the sky) can the signal be tentatively considered extra-terrestrial in nature. Spikes (short radio bursts) above a threshold value, doublets and triplets are also recorded.

Depending on how the telescope was moving when the work unit was recorded, the computer will do between 2.4 trillion and 3.8 trillion mathematical operations (flops or floating point operations) to complete its work.  Depending on how powerful the volunteer’s computer is, the time taken for processing one full work unit may range from 3 to 50 hours! These calculations include a fast Fourier transformation of the signal data to yield a frequency spectrum.

The following is how a typical SETI@Home screensaver on the user’s computer screen may look like:

The initial software platform, now referred to as "SETI@home Classic", ran from May 1999 to December 2005. This program was only capable of running SETI@home.  It was later merged with BOINC (Berkeley Open Infrastructure for Network Computing), which also allows users to contribute to other distributed computing projects at the same time as running SETI@home. The more versatile BOINC platform (called SETI@home II) allows testing for additional types of radio signals.  Also, it covers an enhanced bandwidth of 50 MHz over 700 million channels. 

Project Phoenix

Project Phoenix is a complimentary SETI project involving the analysis of patterns in extraterrestrial radio signals. It is run by the independently funded SETI Institute of Mountain View, California, USA.  It  started work in February 1995 with the Parkes radio telescope located in New South Wales, Australia, the largest telescope in the southern hemisphere. Between September 1996 and April 1998, the Project used the National Radio Astronomy Observatory in Green Bank, West Virginia, USA.

Rather than attempting to scan the whole sky for messages, this Project concentrates on nearby systems that are similar to our own (i.e., those most likely to have planets capable of supporting life). It has concentrated on about 800 stars within a 200 light-year range.

The Project searches for radio signals as narrow as 1 Hz between 1,000 and 3,000 MHz, a broader bandwidth compared with the conventional SETI searches.

In March 2004 the Project announced that after checking the 800 stars on its list, it had failed to find any evidence of extraterrestrial signals. This may possibly mean that our solar system is located in a rather ‘quiet’ neighborhood.

Optical SETI@berkeley

In the Radio SETI@home project, the signals are assumed to be transmitted isotropically from the source, with just a tiny fraction of it being intercepted by earth based instruments.  The Optical SETI@berkeley project, initiated in 1997, is based on the assumption that a distant civilization might take recourse to sending highly focused pulses deliberately towards our solar system (This implies that it has already identified us as a potential intelligent civilization).  Such nanosecond-scale optical (laser) pulses are not known to originate naturally from any astronomical source.  The idea of looking for pulses in the optical band of the electromagnetic spectrum was suggested as far back as 1961 by Townes (a co-inventor of the LASER and Physics Nobel laureate) and Schwartz.

The optical pulse search employs a 30-inch automated telescope equipped with a super sensitive photometer system located at a University of California campus near Berkeley.  

Advertising our presence

Our attempts to discover ETI should be complimented by efforts to announce our own existence in the solar system to nearby systems that may be harboring extraterrestrial intelligence.  The first such attempt was due to Carl Sagan who persuaded NASA to include a plaque specially designed by him as part of the Pioneer deep space probes launched in 1972 and 1973.  The plaque shown here carries a coded pictorial message giving some basic information about ourselves and the planet we live in.  A much more complex and detailed message was included in the Voyager spacecraft launched in 1977.  It was in the form of a golden phonograph record containing sounds and images portraying the diversity of life and culture on earth.

The probability of a space faring civilization discovering and intercepting these messages is so ridiculously small that these efforts can only be viewed as symbolic gestures.  A more productive venture would be to send very strong radio signals or laser beams carrying coded information much the same way that we expect other ETIs to communicate with us.  This has been done in recent years though not in a very organized and systematic manner.  In any case, much of the radio and TV signals generated on the earth have leaked out into interstellar space over the last 60-70 years though the strengths of these signals are far too weak compared to what we ourselves expect from ETIs.  

One inherent assumption in any SETI effort is that the communicating civilizations must be sufficiently advanced to have mastered the technology of radio or other electromagnetic wave communications.  Obviously, if and when we discover such signals, the farther the location of the source the more technically advanced is the civilization we have to deal with.  It will almost certainly be far more advanced than we are on earth.  After all, our communicative capabilities are less than a century old.  We are only like a new born baby in a cosmic cradle. 

The Drake Formula for Advanced Technical Civilizations

The Drake Formula was developed by Frank Drake in 1961 as a way to focus on the factors which determine how many intelligent, communicating civilizations there might be in our galaxy.  The formula itself and the best estimates given by Carl Sagan, a SETI pioneer, are given in the appended texts.  It is amazing to think that under this estimate our galaxy alone has about ten million advanced technical civilizations!  The fundamental question facing humanity is therefore not whether anybody is out there but how to locate them and communicate with them.  The ‘search’ aspect of SETI naturally takes precedence over CETI (Communication, and later perhaps contact, with Extra Terrestrial Intelligence).

In the Drake Equation, N* represents the number of stars in the Milky Way for which a reasonable estimate is 400 billion. 

f_p is the fraction of stars that have planets around them.  Thanks to great advances in opto-electronic technology in recent years, quite a number of (large) planets have been discovered.  A spate of new discoveries, including earth-like planets, is on the cards in the coming years.  Planetary systems appear to be much more common than believed earlier.

n_e is the number of planets per star that are capable of sustaining life.  In our Solar System this number appears on current evidence to be just one. A more liberal value of two is used in Sagan’s estimate.

f_l is the fraction of planets in n_e where life evolves.  There is no reliable basis for estimating this.

f_i is the fraction of f_l where intelligent life evolves.  f_c is the fraction of f_i that develops into an advanced communicative civilization.  It is very difficult to estimate the two separately.  In Sagan’s estimate the product of the two factors is taken to be 0.01.

f_L is the fraction of the planet's lifetime during which the communicating civilizations live or survive.  This is the toughest of the questions involved in Drake’s equation. If we take Earth as an example, the expected lifetime of our Sun and the Earth is roughly 10 billion years. So far we've been communicating with radio waves for less than 100 years. How long will our civilization survive? Will we destroy ourselves in a short period like some futurologists predict or will we overcome our problems and survive very long? Only the future holds the answer.

The true value of the Drake formula is not so much in the answer itself as in the questions that are thrown up when attempting to come up with an answer. Obviously there is a tremendous amount of guess work involved when estimating the variables. However, as Astronomy, Biology, and other sciences and technology march on, the answers to these questions will emerge with continually greater reliability.

Scale of the SETI@home effort

The SETI@Home project that has been running for about eleven years now has had over 5 million voluntary contributors, with about a third of them involved actively for much of this period.  Incidentally, I have been contributing significantly as a volunteer (see certificate appended) to this and other BOINC managed distributed computing projects and is among the top 6% of the SETI@home contributors worldwide (top 2% from India) since the year 2000. Billions of work units have been processed, analyzed and studied.  Over 5 million years of actual computing time has been invested in the effort, most of it coming from the volunteers all over the world.  It has already become the largest distributed computing project in history.

[Cobblestone (named after Jeff Cobb of SETI@home) is BOINC's unit of credit and is 1/200 day of CPU time on a reference computer that does 1,000 FLOPS based on the Whetstone benchmark]

Among the billions of work units processed so far only about 3000 have proved to be of potential interest. The rest of them have been found to be of terrestrial or natural origin.  No ‘signature’ has yet been detected of any extra terrestrial intelligence.  However, scientists recognize that a much greater effort needs to be mounted and run for several more decades before any definitive indicator can emerge.

Hunt for Exoplanets

It is just 15 years since the first extrasolar planet was discovered around an ordinary star in our galaxy.  More than 450 exoplanets have been identified since then and the number has been growing rapidly.  Understandably, most of the early discoveries were of giant Jupiter like planets.  However, with major improvements in earth-based detection techniques and the NASA Kepler spacecraft launched last year specifically for such a purpose, multiple planet systems and even earth sized planets are being added to the exoplanet population.  Preliminary findings indicate that one of them is inside the ‘goldilocks’ (potentially habitable) zone around its parent star.  With earth like physical conditions, particularly a ‘tolerable’ temperature range, likely to prevail, such planets are the most likely candidates for the existence of advanced life forms.  If their number grows at the expected rate, Carl Sagan’s estimate for n_e in the Drake Equation, which has been considered by some as too optimistic, may not really be so. 

 

The coming years are poised for some tremendously exciting discoveries that may strengthen our expectations of ETI elsewhere in our galaxy, though not necessarily in our near neighborhood.

Postscript

The question of ETI belongs at present to the realm of speculation/belief, but based on sound scientific foundation.  It is also based on the realization that the Laws of Science are truly universal, at both macroscopic and microscopic levels.

 

Evolution of life on Earth may be accidental (due to coincidence of a number of individually improbable events), but this ‘accident’ must have been replicated on a large number of planets in the cosmos.  From a philosophical, psychological and practical point of view it would be the height of egotism and stupidity, a throwback to the pre-Copernican geocentric era, to assume that we are alone in the vast universe.  As Carl Sagan has pointed out, such loneliness would be of a most profoundly disturbing character. In the deepest sense, the search for ETI would be a search for ourselves.

SETI involves finding powerful new ways to distinguish a genuine alien transmission from the vast earthly and cosmic background noise. It is like locating a needle in the cosmic haystack.   Many decades of sustained and systematic efforts are called for before the search leads us anywhere.  As of now, despite years of intense effort under SETI@home and other projects, we have not been able to find any definitive evidence of extra terrestrial intelligence. However, absence of evidence does not amount to evidence of absence.