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Yesterday, June 5, was 'Zero Shadow Day'. On Monday at 11.35 a.m., residents of Kolkata witnessed a fascinating celestial event at Salt Lake and Bidhannagar areas in Kolkata. This 'Zero Shadow Day' happens only twice a year. On this day, no shadows are formed when the sun is exactly overhead due to sunlight. This was Kolkata’s first Zero Shadow Day of the year. However, in other locations, the day of zero shadow will vary depending on their position between the two tropics. This rarest cosmic event happens twice a year.
The founder member of the Kolkata Astronomy Centre, Anupam Naskar, said that the people of Barasat, North 24 Parganas district, and the adjoining Madhyamgram area are going to witness the ‘Zero Shadow Day’ between 11.34 a.m. and 11.41 a.m. on June 6, Tuesday.
But do you know what happens in ‘Zero Shadow Day’? How is this magic possible?
Zero Shadow Day is a phenomenon that occurs twice a year when the sun's position is directly overhead, casting no shadows on the earth's surface. During Zero Shadow Day, the sun reaches its highest point in the sky, reducing the length of the shadow. When we stand on this shadow, our own shadow becomes invisible, hence the term "Zero Shadow". The Astronomical Society of India has explained this ‘Shadowless Phenomenon’ by saying that for people living between +23.5 and -23.5 degrees latitude, the sun's declination will be equal to their latitude twice: once during Uttarayan and once during Dakshinayan. On these two days, the sun will be exactly overhead at noon and will not cast a shadow on an object on the ground.
Not only people from Kolkata but also people from Bangalore and Mumbai have witnessed this Zero Shadow Day moment this year. Residents of Bengaluru witnessed Zero Shadow Day on April 25. The entire city was shadowless for a few minutes. On May 15, the Mumbaikars became shadowless; they celebrate ‘Zero Shadow Day’ on May 15 and July 28 every year.
The Birla Planetarium of Kolkata informed the Kolkata people that Kolkata will be shadowless again in the month of July for the second time this year on July 8 at 11.41 a.m.
