BENGALURU: Bengalureans will witness Zero Shadow Day (ZSD) on April 24. This is related to a rare phenomenon, scheduled to be seen at 12:17 pm for an entire minute, where there will be no shadows on any perpendicular objects.
This phenomenon occurs when the Sun is located directly above the equator, and its rays fall perpendicular to the Earth’s surface.
This means that the Sun will directly be overhead, and hence, any vertical objects on the Earth’s surface will not cast any shadow.
“This happens for places between the Tropic of Cancer and the Tropic of Capricorn,” said the Indian Institute of Astrophysics (IIA). This occurs between April and August in the country and its surrounding areas -- located between +23.5 and -23.5 degrees latitude.
“The arc of the Sun keeps changing over the year,” mentioned an IIA professor. During these months, if one observes every sunrise and sunset in the coastal regions, the points keep changing. From March, the sun starts moving South-East, and it moves back in the centre in September and again moves North-East over a period of time, and the cycle continues. Hence, the phenomenon can be witnessed twice a year.
On April 25, the IIA campus in Koramangala will be organising a talk to explain the ZSD concept, which will showcase a real-time, hands-on demonstration. The institute also has an app to show ZSD for several locations and lets one interactively understand the celestial occurrence.
The next Zero Shadow Day in Bengaluru will be observed on August 18. Zero Shadow Days fall on various days for different places. For example, Kodaikanal witnessed its ZSD last week and it was observed in Chennai on April 24. In the country, the phenomenon is seen only between Kanniyakumari and Bhopal.