What is Zero Shadow Day?

Zero Shadow Day is a remarkable celestial event that transpires twice a year within locations ranging from +23.5 to -23.5 degrees latitude. During this occurrence, the sun reaches its peak elevation in the sky, causing objects and individuals to cast no shadows.

As per Britannica, declination refers to the angular distance of a celestial body north or south of the celestial equator. On the other hand, according to National Geographic, latitude is the measurement of distance north or south of the Equator. It’s determined by the imaginary lines, known as parallels, that encircle the Earth parallel to the Equator in an east-west direction.

Also read: What is zero shadow day? Unique celestial event set to grace Bengaluru on August 18

What happens on a Zero Shadow Day?

During a Zero Shadow Day, the sun is positioned directly overhead, resulting in the absence of shadows on the earth’s surface. This occurrence causes the sun to reach its zenith in the sky, leading to a significant reduction in the length of shadows, rendering them practically invisible.

Also read: Kolkata to witness ‘Zero shadow moment’; Here’s what is it? Why it happens?

What to expect on this day?

When the sun occupies the zenith position, it does not cast a shadow on any object according to the Astronomical Society of India (ASI). For individuals residing between +23.5 and -23.5 degrees latitude, the sun’s declination aligns with their latitude twice a year—once during Uttarayan (Northern Solstice) and once during Dakshinayan (Southern Solstice). On these specific days, precisely at noon, the sun appears directly overhead and fails to cast shadows on objects situated on the ground.

Similarly, Hyderabad also witnessed Zero Shadow Day earlier on August 3 at 12:23 pm, during which the sun was positioned directly overhead, causing the shadows of vertical objects to vanish temporarily. Additionally, Hyderabad had previously observed Zero Shadow Day on May 9 of the same year.

Updated: 18 Aug 2023, 08:52 AM IST