Kolkata: "I have a little shadow that goes in and out with me, And what can be the use of him is more than I can see. He is very, very like me from the heels up to the head; And I see him jump before me, when I jump into my bed." Remember Robert Louis Stevenson’s famous poem ‘My Shadow’ where the little boy complained of the shadow sticking to him all through the day but on Sunday-- on the day of Jamaisashti, a Bengali ritual where the sons-in-law are treated with lavish meals -- shadow will leave.
In the language of Astro-science, this rare cosmic phenomenon is termed ‘Zero Shadow-Day’, a particular time when there will be no shadow. In Kolkata at 11.34 am the people of the city will find the disappearance of the shadow at least for 55 seconds. The city will have its zero-shadow moment on June 5 when there will be no shadow from sunlight at a particular time of the day. This happens twice a year when the sun is exactly overhead. On its return path (called Dakshinayan) the sun will again be exactly overhead in Kolkata on July 7 at around 11:41 am and the day will be the second zero shadow day of the year.
According to Astro-science any form of the visible light falling on an object generally produces a shadow, unless it is exactly above the object. People and any object, all around the world, living between the Tropic of Cancer and Tropic of Capricorn (+23.5- and -23.5-degrees latitude) lose their shadows, though momentarily, twice a year. These two days are called zero shadow days.
The city is around 2,500 km from the equator and around 93.5 km from the Tropic of Cancer, the imaginary line which passes close to Krishnanagar in the Nadia district. Every year on the zero shadow days, students and astrophiles, who are located between the two Tropics erect vertical poles, and different objects and sometimes even stand outside to see for themselves the cosmic event. Different cities where the zero-shadow day has already occurred this year, have experienced the zero-shadow moment when every object under the sun lost its shadows for a few moments.
