Scientific view of Ira Sevaya at Sri Pada

by K. R. Abhayasingha
 

The Sri Pada season started on December 1, 2009, the Uduwap Poya day. It will terminate on the Vesak Poya day this year. Sri Pada Mountain is also known by names like Samanala Kanda, (Samanala Mountain) and Adam's Peak.

Every year millions of pilgrims, irrespective of their religion, join processions to climb the Samanala Mountain to worship the footprint of the Buddha. If it is not for worshipping, no one will climb the hill particularly in the night. Even if one climbs the hill for personal requirements he never spends the night hours on top of the hill.

For this reason, the pilgrims have a series of beliefs, expectations and myths about their experience and sights of many events which are not common in their day to day life. Even though all of them are natural events, pilgrims understand them as events that occur only in the Adam's Peak environment and many believe that such events have close relationship to the footprint and the God Saman (Saman Deviyo).

The Ira Sevaya, (fluctuation of sun's images a few minutes before sunrise) is one of the most beautiful and colourful visual observations one can see in the world. When one observes the sky in the early morning from the Adam's Peak, the eastern sky over the horizon changes its colours very fast. So pilgrims can observe beautiful designs in the sky and changes of colours just like the observations when he is in front of an expert painter.

Mixed with all this colouring effect, the sun (apparently images of the sun) can be seen above the horizon. It is not a single image, but plenty of them. The images are seen in different locations before you see the actual sun above the horizon a little later. One who does not know what is really happening in the eastern sky, may believe that the sun moves up and down several times to worship the footprint of the Buddha as it is mentioned so in myths about Sri Pada. As it is not an easy thing to count the number of visible images of the sun and most of the pilgrims including some veteran Buddhist monks and learned professors use to say that Sun worships three times the Buddha's foot step before it rises. As the event could not be explained with believable words not only the lay-pilgrims, but also religious pilgrims including Buddhist monks still have belief of the God sun (Hiru Deviyo) worshipping the footprint of the Buddha before it starts provision of energy to the world.

It is pathetic to see that some media personnel, Buddhist monks and learned professors taking part in television programs broadcast from the Sri Pada still explaining this event to listeners without considering the science behind these natural events.

This so called Ira Sevaya or the apparent movement of the sun before sunrise is not a sight special to Sri Pada or Sri Lanka but it can be seen from any hill top and also from airplanes, provided the clear sky environment is available over the eastern sky and the observer is at a significantly high altitude. I have heard that special locations on top of hills in some parts of India have been reserved for tourists for them to observe this beautiful scenery.

A light ray encounters a number of effects when it travels in a media or passes a sharp edge, or travels through a common surface between two transparent media like water and glass or air and glass or even air-layer and another air-layer if two layers have different characteristics. Such behaviours are explained under the terminology like Reflection, Refraction, Diffraction, Scattering, Diffusion and Total Internal Reflection which have meanings different from each other.

If one has studied these phenomena in Physics (Advanced Level or higher levels), he can explain the science of the natural events like rainbow, mirage, fluctuation of sun before sun rise, eclipses, halo event and colourful pattern seen in the sky particularly in North Pole and South Pole skies.

The apparent movement or shift of the sun a few minutes before sunrise seen at the top of a hill is caused both by Total Internal Reflection (TIR) and diffraction of sun's light beams by the lower atmosphere.

Light rays go through Total Internal Reflection (TIR) when they meet a common boundary between two media one denser than the other (like glass and water, water and air or glass and air). Requirement for a beam to undergo TIR is the incident rays should travel through the dense medium before meeting the common boundary. When the incident angle exceeds a particular value (called critical angle), rays are reflected just like they are reflected by a plain mirror.

Light rays from the un-risen sun are incident through the dense air which is at very low level, close to the earth surface, of the atmosphere towards rare (low dense) layers which are above surface layers. Under these circumstances, light rays get reflected towards the dense layer at boundaries separating dense/rare air layers. Even though the actual position of the sun at this time is covered by the solid earth for an observer/pilgrim at the top of a hill like Sri Pada, he can see the sun through the reflected light rays. The apparent positions of the sun which are seen through reflected rays are images of sun and are seen above the horizon (see the diagram).

As all of these happen while the sun and the earth are relatively moving, an observer sees a large number of images of the sun when the time passes and the apparent positions of images are not the same. The observers may understand these changing of positions of suns images as movement of sun up and down.

A few minutes later, the sun rises above the horizon and this is the real sun. As the Total Internal Reflection does not occur now one can see only one figure which is the real sun just above the horizon. This position of the real sun is usually below the positions of the images he saw a little early.

This phenomenon TIR is shown in the diagram. Please note that the diagram is not drawn to a scale and is a little exaggerated to show you the phenomenon clearly.

Ira Sevaya may be partly a result of the diffraction of solar light beams at the tip of the earth in the early morning.

A light ray finds the body of the earth as a tiny sharp edge and therefore it undergoes through the phenomenon diffraction at the earth surface and breaks the ray into a number of branches which are transmitted in different directions. Similar in TIR, a number of images are formed by diffraction too and an observer on a high location can see fluctuation of images of the sun again before sunrise. Both of these phenomena, Total Internal Reflection and diffraction, may cause the so called Ira Sevaya which is a natural event happening all over the world every day. Both sun and earth are moving and rotating bodies. Sun is common to the whole world and it provides energy to the whole world positioning billions of kilometers away from us not close to Adam's peak. Before it rises over the horizon seen from Sri Pada hill, it spends hours in the sky in other parts of the world!.

Present day children should be directed in the correct way to understand the real facts of our universe and other matters related to it. Myths and beliefs will mislead the educating children and it is the rights of all responsible personnel including lecturers, teachers and also media personnel to highlight the truth about the natural events not the myths. Otherwise the next generation will be never armed with scientific understanding to face the present and future world.

The writer is former Director of Meteorology

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