Zero Shadow Day 2025: Date, Time, and Other Key Details

Zero Shadow Day is a celestial event which occurs twice in a year. On this event, no shadows of any object or person can be observed. This event takes place on specific date and times, and is very short lived. This year, Zero Shadow Day will be observed in Bengaluru on Apr 24, 2025 at 12:17pm. 

What is Zero Shadow Day?

Zero Shadow Day occurs when the Sun is positioned exactly overhead at local noon, causing vertical objects to cast no shadow for a short period. This phenomenon is possible only in places situated between the Tropic of Cancer (23.5°N) and the Tropic of Capricorn (23.5°S), where the Sun’s apparent path in the sky can align perfectly with the zenith (the point directly above an observer).

• Why does it happen?
  Earth's axis is tilted approximately 23.5 degrees from its orbit around the Sun. When the Earth rotates, this tilt results in the position of the Sun in the sky changing north and south during the course of the year. At two times of the year, for points inside the tropics, the Sun's rays are perpendicular to the ground at local noon, destroying shadows on vertical objects.

• When does it happen?

Every place in the tropics has two Zero Shadow Days a year: one when the Sun travels north (between March equinox and June solstice) and another when it travels south (between June solstice and September equinox).

Zero Shadow Day in Bengaluru

Bengaluru, at around 13°N latitude, sees Zero Shadow Day every six months. In 2025, it will fall around April 24-25 and then again on August 18. On both these days, between 12:17 PM and 12:23 PM, the Sun is exactly overhead, and vertical objects—such as poles, trees, or even human beings—leave not a shadow on the ground.

How is it celebrated?

Citizens and stargazers alike can observe the phenomenon by positioning a vertical stick or any standing object outside at the given time. For some minutes, the shadow will reduce and vanish entirely, only to reappear on the other side as the Sun continues its course.

Is Zero Shadow Day Specific to Bengaluru?

Zero Shadow Day is not specific to Bengaluru. It is observed by all places that lie between the Tropic of Cancer and the Tropic of Capricorn, but the precise dates and times differ based on the latitude of every place.

Examples of Zero Shadow Day Dates in Indian Cities

This means cities across southern and central India—such as Hyderabad, Mumbai, Kanyakumari, and Bhopal—also witness Zero Shadow Day, but on different dates and at slightly different times, determined by their latitude.

The Broader Significance

Zero Shadow Day is more than a curiosity—it is a vivid demonstration of Earth's axial tilt, the geometry of sunlight, and the movement of celestial bodies. It also has practical applications in architecture and solar energy, as understanding the Sun’s path is crucial for designing buildings and solar panels.

“Zero Shadow Day not only offers a moment of wonder but also serves as an educational opportunity that highlights the intricate movements of celestial bodies. It will demonstrate the precision of our planet's tilt and its consistent path around the sun, making it a significant event for astronomy enthusiasts.”