When the Sun Stands Directly Overhead
On April 24, Bengaluru experienced a unique and rare celestial event known as Zero Shadow Day. For a brief moment around midday—specifically between 12:17 PM and 12:23 PM—vertical objects, including people, cast no visible shadow. The spectacle left many residents awestruck, as even towering poles and trees momentarily seemed to lose their silhouettes.
This phenomenon occurs twice a year in places situated between the Tropic of Cancer and the Tropic of Capricorn. Bengaluru, lying at roughly 13° North latitude, is among the cities fortunate enough to witness this fascinating event.
What is Zero Shadow Day?
Zero Shadow Day takes place when the Sun is exactly overhead at solar noon. At this moment, sunlight strikes the ground at a perfect 90-degree angle, meaning vertical objects cast no shadow. This occurs when the Sun’s apparent position in the sky (declination) matches the latitude of the location on Earth.
It’s all thanks to the Earth’s axial tilt of approximately 23.5 degrees and its orbit around the Sun. As the Sun appears to travel between the Tropic of Cancer and the Tropic of Capricorn during the year, different places along this belt experience Zero Shadow Day on two separate days annually.
Science Comes Alive for the Public
To mark the occasion, several educational institutions in Bengaluru organized demonstrations, shadow experiments, and interactive sessions for students and astronomy enthusiasts. Activities included:
- Measuring shadow lengths with sundials and rulers
- Calculating the Earth’s circumference using traditional methods
- Hands-on sessions to explain the Earth’s tilt and orbit
These efforts aimed to make science more tangible, turning a celestial event into a real-time classroom.
When Will Other Cities Witness It?
Zero Shadow Day doesn’t occur on the same day for every city. Its timing depends on a location’s latitude. Here are some upcoming dates for other Indian cities:
- Kanyakumari – April 10 & September 1
- Hyderabad – May 9 & August 5
- Mumbai – May 15 & July 27
- Bhopal – June 13 & June 28
Each city experiences this solar alignment on slightly different days, but the phenomenon remains the same—an awe-inspiring moment of zero shadow.
Why It Matters
Beyond its visual wonder, Zero Shadow Day offers a real-world demonstration of astronomical principles like Earth’s rotation, revolution, and axial tilt. It connects classroom learning with observable reality, making abstract concepts easier to grasp.
More than just a photo opportunity, it is a reminder of the cosmic dance we’re all a part of. These events inspire curiosity, promote science education, and ignite a fascination for the universe.