What is zero shadow day? Unique celestial event set to grace Bengaluru on August 18
report for LiveMint, astrophysicist Debiprosad Duari noted that “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." Moreover, according to the Astronomical Society of India (ASI), people living between +23.5 and -23.5 degrees latitude Sun's declination will be equal to their latitude twice a year. Sun is exactly overhead at noon on these two days and does not cast a shadow on objects on the ground.
As per Britannica, declination is the angular distance of a body north or south of the celestial equator. While as per National Geographic, ‘Latitude is the measurement of distance north or south of the Equator.
It is measured with 180 imaginary lines that form circles around Earth east-west, parallel to the Equator.’ Bengaluru had earlier observed Zero Shadow Day in April this year when all vertical objects in the city became shadow-less for a short period of time at 12.17 pm. Similarly, Hyderabad had witnessed Zero Shadow Day earlier on August 3 at 12:23 pm when the sun was directly overhead and shadows of all the vertical objects disappeared briefly.
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