Bengaluru’s Shadows Take a Holiday: Zero Shadow Day Returns April 24

On April 24, Bengaluru will experience a phenomenon known as Zero Shadow Day.  The sun will be directly overhead at 12:17 PM. For a short time, vertical objects, including poles and people, won't cast a shadow since the sun's rays are hitting the ground at a 90-degree angle.

 

Colloquially, the occurrence can be called a "solar zenith" and happens twice a year, in cities located between the Tropic of Cancer and the Tropic of Capricorn, such as Bengaluru.  Bengaluru has its first instance roughly around the April 24-25 time frame at noon, and then experiences the phenomenon again in August. The cause for this occurrence is the tilt of the Earth's axis and its orbit around the sun, which creates this specific alignment of the sun's zenith occurring directly over the latitude of the city. 

 

The Indian Institute of Astrophysics (IIA) will celebrate the day with public events on its Koramangala campus from 10 AM to 1 PM. Someone will conduct demonstrations, while others will have opportunities to observe and take measurements of their shadow lengths. The events will be educational corresponding to the science behind the phenomena of Zero Shadow Day and motion of the Earth in space.  

 

The public is invited to go outside at 12:17 PM to see their shadows disappear as an example of the transitional dynamics of the Earth and the sun. 

         

Source: The Economic Times