Hyderabad: Visitors and invited students at the BM Birla Science Centre on Tuesday witnessed the Zero Shadow day at around 12.31 pm.
Zero shadow day is observed when the Sun does not cast a shadow of an object at noon, when the sun will be exactly at the zenith position. The phenomenon is witnessed twice a year in locations between +23.5 and -23.5 degrees of latitude (between the tropics of Capricorn and Cancer).
During this, the sun’s position is at its zenith (highest imaginary point directly above a location, on the imaginary celestial sphere). Since the earth is tilted at 23.5 degrees to the plane of its revolution around the sun, for people living in +23.5 and -23.5 degrees latitude, the sun’s angular distance of a point north or south of the equator will be equal to their latitude twice a year; once when it is moving from the north towards the equator (Uttarayan) and once when it is moving south to the equator (Dakshinyan).
Earlier, Hyderabad witnessed the Zero Shadow day on May 9 this year.
According to BM Birla Science director Dr KG Kumar Director, the northernmost and the southernmost points are the two solstices (summer and winter for each hemisphere) and the crossing of the Sun across the equator are the two equinoxes (spring and fall for each hemisphere).
Dr Kumar said that the Sun is moving south to the equator (Dakshinyan ( and said that on these two days around noon the Sun will be perfectly overhead and thus no shadow of any object will be cast. Every year the dates, however, vary for different locations on Earth.