Follow Mint Lounge

Latest Issue

Home > Smart Living> Environment > Explained: Why Bengaluru will witness Zero Shadow Day this week

Explained: Why Bengaluru will witness Zero Shadow Day this week

Here's everything you need to know about a rare celestial event that Bengaluru is set to witness on 18 August

Bengaluru is set to witness Zero Shadow Day on 18 August.
Bengaluru is set to witness Zero Shadow Day on 18 August. (HT Photo)

Bengaluru is set to witness an interesting celestial event, called a Zero Shadow Day, on 18 August. The city will experience this for the second time this year. On 18 April, Bengaluru observed Zero Shadow Day when, at 12.17 pm, shadows of vertical objects momentarily didn’t appear. Previously, Hyderabad observed this phenomenon on 3 August and Mumbai witnessed Zero Shadow Day on 15 May between noon and 12.30 pm.

Also read: July was officially the hottest month on record, says new report

What exactly is Zero Shadow Day?

According to the Astronomical Society of India, it’s a day when the Sun does not cast a shadow on an object at solar noon and will be exactly at its highest position. This unique event occurs twice a year in the locations +23.5 and -23.5 degrees latitudes.

In a June 2022 report published in Livemint, astrophysicist Debiprosad Duari explained the event further. While it's known that any form of visible light falling on an object generally produces a shadow, this changes when it is exactly above the object. “People and any object, all around the world, living between the Tropic of Cancer and Tropic of Capricorn (23.5 and -23.5 degrees latitude) lose their shadows, though momentarily, twice a year. These two days are called zero shadow days,” Duari explains in the Livemint report.

These dates will differ based on the location. It occurs when the Sun’s declination is equal to the latitude of the location. Notably, the shadow doesn’t really disappear but it is under the object. The lack of show is because of the tilt of the earth’s axis and its rotation around the sun. “This tilt causes the angle of the sun’s rays to change throughout the year, which in turn shows various lengths and directions of shadows,” director of G.P. Birla Archaeological Astronomical and Scientific Research Institute K.G.Kumar told The Hindu in an article published on 1 August.

When will it occur?

The event will take place around noon on 18 August in Bengaluru. For a brief period, any object placed under the Sun will not cast any shadow, a rare event that is experiential learning for students and others. As the sun will be at its highest point, experts say precautions should be taken to ensure safe observation. 

Also read: Explained: All you need to know about the Isro Aditya-L1 mission

Next Story