On Tuesday, the Zero Shadow Day was observed in Ennore and Minjur, and on Thursday it will be observed in Mahabalipuram, Tirupur and other places. 

“When the sun moves from East to West at any time, it will be directly overhead and the shadow will not fall on the foot. This effect does not happen every day, but only two times a year. Zero Shadow Day is usually observed in March and August, and it also differs from place to place. This is because the sun does not have East to West movement instead but has North to South, which moves between the Tropic of Cancer and Tropic of Capricorn. Between these, for two days at any given time, the sun will be overhead and there won’t be casting of shadow,” said IK Lenin Tamilkovan, Scientific Officer, Periyar Science, and Technology Centre. 

Even in March 2021, the science centre had observed the day. They also have an app ‘Zero Shadow Day (ZSD)’, which has the world and India map showing the exact details of where the shadow day is being observed and its timings. 

“The day will be observed in Puducherry on August 21, as the sun is moving towards the south. We cannot expect that no shadow will be observed for 10 to 15 seconds, as the Earth rotates faster,” said Lenin.