As scientists prepare for the most significant solar eclipse of the century on July 22,noted heliologist Dr Hari Om Vats is demystifying the shadow bands that occur before and after a solar eclipse. The associate professor at the Physical Research Laboratory (PRL) was in Vadodara to talk to the budding astronomers and students about how shadow bands render valuable data about the atmosphere,especially about pollution. In a tête-à-tête with Anupam Chakravartty,Dr Vats explained the importance of studying the shadow bands. * A theory suggests that shadow bands are not just visual events but also sonic,as the moon is believed to move at a supersonic speed,creating various sound waves during the solar eclipse. What do you think about this?Shadow bands are constructive and destructive interferences of light before and after a solar eclipse is noticed in areas of low elevation. In laymans words,it is the play of light and shadow preceding and succeeding a total solar eclipse noticed from earth. It is merely a visual spectacle that can render important data about solar eclipse and the atmosphere,including pollution in the atmosphere. That shadow bands are a sonic event is yet to be proved,as it is not the moon but its shadow that moves at a supersonic speed during the time of eclipse. * What is Indias contribution to the study of shadow bands so far?Maitri,our station in Antarctica,got the first chance to study shadow bands on November 23,2003 for 11 minutes at a stretch,which is extremely rare. It happens in about 1,000 years. Many other countries had studied that eclipse,but for us it was an exclusive opportunity. As Maitri is located on the edge of the Indian Ocean at a gradient of 12 degrees,we could witness six minutes of shadow bands before the event and four minutes after it. Two of my colleagues,S P Bagare and S M Bhandari,and I had suggested the Indian government that we should study these bands. * You are known for your study of solar flares,which,over the last few years,have caused disruption of communication satellites. Are we going to face more such disruptions? It may be interesting to note that scientists across the world in 2005 had said that spots in the sun would increase to 50. However,our latest study reveals that there are about two to three spots on the surface of the sun. Certainly,it is not just the spots that cause the solar flares,but also increased activity above the surface of the sun that causes these flares to enter the atmosphere. There are bound to be more disruptions because there is a manifold increase in the number of satellites that relay the communications to us. In case of solar flares,we have not yet made any significant advances in the predictions. Therefore,it will be difficult for us to predict how it will shape up in the future. However,flares are cyclical unlike the global weather,which is changing permanently because of rapid industrialisation. * What is the significance of the solar eclipse on July 22 and how will be the observations made in Gujarat important?The solar eclipse would be the greatest,as the Sun and Moon would be farthest from earth. Therefore,the shadow bands are expected to have larger areas under it. Gujarat being at a low elevation would render important data not just about the turbulences in the atmosphere but also about pollution. * How are you planning to promote it? We have taken the help of various organisations and institutions. We would set up 30-40 observation points from Gujarat spanning Madhya Pradesh,Bihar and the Northeast,wherein common people along with the enthusiasts would get the chance to observe the eclipse and play of light. This would in turn dispel the superstitions in a large number of people who feel that solar eclipses are caused by Rahu and Ketu (laughs). NGOs to hold seminars to dispel eclipse myths In order to promote scientific temperament in the city,the Gujarat Nature Conservation Society (GNCS),along with organisations from Bharuch and Surat,is going to organise various seminars on and before July 22,when the Total Solar Eclipse would occur between 6 and 9 am. According to the chief education officer of GNCS,Mukesh Pathak,eclipse observation programmes in collaboration with amateur astronomy associations would be held in the city. We are finalising a plot of land for our observations with various instruments to observe the eclipse in the city, added Pathak. He said the involvement of common people is vital.
