What Is Zero Shadow Day? Hyderabad Set to Witness Rare Sun-Overhead Phenomenon
The event occurs only in regions located between the Tropic of Cancer and the Tropic of Capricorn.
Hyderabad is set to experience the fascinating astronomical phenomenon known as Zero Shadow Day tomorrow, a rare event during which the Sun appears directly overhead at noon, causing vertical objects to cast almost no shadow.
The event occurs only in regions located between the Tropic of Cancer and the Tropic of Capricorn.
What Is Zero Shadow Day?
Zero Shadow Day takes place when the Sun reaches a position exactly overhead at local noon. At that precise moment, vertical objects such as poles, bottles, trees and even people cast extremely short or nearly invisible shadows.
The phenomenon occurs because Earth’s axis is tilted by about 23.5 degrees as it revolves around the Sun. This tilt causes the apparent movement of the Sun between the northern and southern hemispheres throughout the year.
Why Does It Happen?
As Earth revolves around the Sun:
The Sun appears to move northward during Uttarayan
It appears to move southward during Dakshinayan
Because of this motion, the Sun’s vertical position shifts between:
23.5° North latitude
23.5° South latitude
When the Sun’s declination exactly matches the latitude of a particular place, the Sun appears directly overhead there at noon. This creates the Zero Shadow Day effect.
Cities located within tropical regions experience the event twice every year:
Once during the Sun’s northward journey
Again during its southward journey
When Does Zero Shadow Day Occur in Hyderabad?
Hyderabad lies at approximately 17.4° North latitude, allowing the city to witness Zero Shadow Day twice annually.
The event usually occurs around:
Mid-May
Late July
The exact timing may vary slightly each year depending on solar calculations.
During the phenomenon, objects such as streetlights, buildings, trees, and human bodies appear to lose their shadows for a brief period around noon.
Why Is Zero Shadow Day Important?
Astronomers and science educators consider Zero Shadow Day an important educational event because it helps explain key scientific concepts such as:
Earth’s axial tilt
Change of seasons
Apparent solar movement
Latitude and longitude
Astronomical calculations
Science centres, schools and astronomy clubs often organise public demonstrations and observation activities to help students understand how Earth and the Sun interact.
The event also serves as a reminder of the precision of celestial movements and the role of astronomy in everyday life.